MSc. CIVIL STRUCTURAL ENGINEERING FINAL THESIS

SCHOOL OF CIVIL, ENVIRONMENTAL AND LAND MANAGEMENT ENGINEERING

Building Information Modeling (BIM) Approach for Construction Management and Interoperability Analysis

Master Thesis by: Supervisor: Mertkan MERT Prof. Carlo Iapige De Gaetani 893699

2018 - 2019 Contents

ABSTRACT ...... 1

1. INTRODUCTION ...... 3

WHAT IS BUILDING INFORMATION MODELING? ...... 5 1.1.1. The LOD Concept ...... 5 1.1.2. BIM Parametric Objects ...... 7 1.1.3. BIM Dimensions ...... 8 1.1.4. BIM Levels of Maturity ...... 12 1.1.5. BIM Adoption in the World ...... 14

BIM FOR CONSTRUCTION PROJECT MANAGEMENT ...... 17

INTEROPERABILITY ...... 21

2. INTEROPERABILITY ANALYSIS ...... 25

BIM INTEROPERABILITY ANALYSIS THROUGH IFC STANDARD ...... 33 2.1.1. Benchmark Test Results for Tekla Structures to ACCA Edificius ...... 39 2.1.2. Benchmark Test Results for Tekla Structures to Navisworks ...... 47 2.1.3. Benchmark Test Results for Tekla Structures to Synchro Pro ...... 52 2.1.4. Benchmark Test Results for Tekla Structures to usBIM.viewer+ ...... 57 2.1.5. Benchmark Test Results for Tekla Structures to Solibri ...... 62

GANTT CHART INTEROPERABILITY ANALYSIS FROM TEKLA STRUCTURES TO CPM SOFTWARE ...... 68 2.2.1. Gantt Chart Interoperability Analysis from Tekla Structures to Microsoft Project 2013 ...... 70 2.2.2. Gantt Chart Interoperability Analysis from Tekla Structures to Microsoft Project 2016 ...... 72 2.2.3. Gantt Chart Interoperability Analysis from Tekla Structures to Navisworks ...... 74 2.2.4. Gantt Chart Interoperability Analysis from Tekla Structures to Synchro Pro ...... 80

GANTT CHART INTEROPERABILITY ANALYSIS FROM CPM SOFTWARE TO TEKLA STRUCTURES ...... 82 2.3.1. Gantt Chart Interoperability Analysis from Microsoft Project 2013 to Tekla Structures ...... 82 2.3.2. Gantt Chart Interoperability Analysis from Microsoft Project 2016 to Tekla Structures ...... 84 2.3.3. Gantt Chart Interoperability Analysis from Navisworks to Tekla Structures ...... 86 2.3.4. Gantt Chart Interoperability Analysis from Synchro Pro to Tekla Structures ...... 89

GANTT CHART INTEROPERABILITY ANALYSIS BETWEEN CPM SOFTWARE ...... 92 2.4.1. Gantt Chart Interoperability Analysis from Navisworks to Synchro Pro ...... 92 2.4.2. Gantt Chart Interoperability Analysis from Synchro Pro to Navisworks ...... 93

3. CONCLUSION ...... 96

REFERENCES ...... 100

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List of Tables and Figures Figure 1-1: Life Cycle of A Project (sample building was created in Autodesk Revit 2018) ...... 5 Figure 1-2: Different LOD Levels ...... 7 Figure 1-3: 4D BIM Model View from Synchro Pro...... 11 Figure 1-4: Maturity Levels by Bew and Richards ...... 13 Figure 1-5: BIM Adoption Rate Between 2011-2019 in UK ...... 15 Figure 1-6: BIM Use in China Related to Application Areas ...... 18 Table 1-1: File Exchange Formats Used in AEC Industry ...... 21 Table 2-1: Software Packages Used in This Study ...... 25 Figure 2-1: Workflow for Interoperability Analysis Through IFC Standard ...... 28 Figure 2-2: Workflow for Interoperability Analysis of Gantt Chart from Tekla Structures to CPM Software ...... 29 Figure 2-3: Workflow for Interoperability Analysis of Gantt Chart from CPM Software to Tekla Structures ...... 29 Figure 2-4: Workflow for Interoperability Analysis of Gantt Chart from CPM Software (1) to CPM Software (2) ...... 30 Figure 2-5: Front View of Reference Model ...... 31 Figure 2-6: Back View of Reference Model ...... 31 Figure 2-7: Expected Flawless Interoperability Through IFC Standard...... 33 Figure 2-8: Phases” in Tekla Structures to Add Phase Information to 3D Model ...... 33 Figure 2-9: Phases Produced in Tekla Structures ...... 34 Table 2-2: "Phases" Created in Tekla Structures (1) ...... 35 Table 2-3: "Phases" Created in Tekla Structures (2) ...... 36 Figure 2-10: IFC Export in Tekla Structures ...... 37 Figure 2-11: IFC Interoperability Analysis from Tekla Structures to ACCA Edificius ...... 40 Figure 2-12: ACCA Edificius IFC Import Option ...... 40 Figure 2-13: Front and Back View of the Sample Model in ACCA Edificius ...... 40 Table 2-4: Tekla Structures to ACCA Edificius IFC Interoperability Analysis Result (1) ...... 42 Table 2-5: Tekla Structures to ACCA Edificius IFC Interoperability Analysis Result (2) ...... 43 Table 2-6: Tekla Structures to ACCA Edificius IFC Interoperability Analysis Result (3) ...... 44 Figure 2-14: Description of Element 1 in ACCA Edificius ...... 45 Figure 2-15: Material Type Display in ACCA Edificius for Selected Slab Elements ...... 46 Figure 2-16: Gantt Chart Production in ACCA Edificius ...... 47 Figure 2-17: IFC Interoperability Analysis from Tekla Structures to Navisworks ...... 48 Figure 2-18: Front and Back View of the Sample Model in Navisworks...... 48 Table 2-7: Tekla Structures to Navisworks IFC Interoperability Analysis Result (1) ...... 49 Table 2-8: Tekla Structures to Navisworks IFC Interoperability Analysis Result (2) ...... 50 Table 2-9: Tekla Structures to Navisworks IFC Interoperability Analysis Result (3) ...... 51 Figure 2-19: IFC Interoperability Analysis from Tekla Structures to Synchro Pro ...... 52 Figure 2-20: Front and Back View of the Sample Model in Synchro Pro ...... 53 Table 2-10: Tekla Structures to Synchro Pro IFC Interoperability Analysis Result (1) ...... 54 Table 2-11: Tekla Structures to Synchro Pro IFC Interoperability Analysis Result (2) ...... 55 Table 2-12: Tekla Structures to Synchro Pro IFC Interoperability Analysis Result (3) ...... 56 Figure 2-21: IFC Interoperability Analysis from Tekla Structures to usBIM.viewer...... 57 Figure 2-22: Front and Back View of the Sample Model in usBIM.viewer ...... 58 Table 2-13: Tekla Structures to usBIM.viewer IFC Interoperability Analysis Result (1)...... 59 Table 2-14: Tekla Structures to usBIM.viewer IFC Interoperability Analysis Result (2)...... 60 Table 2-15: Tekla Structures to usBIM.viewer IFC Interoperability Analysis Result (3)...... 61 Figure 2-23: Phase Number Specified in usBIM.viewer ...... 62 Figure 2-24: IFC Interoperability Analysis from Tekla Structures to Solibri ...... 63 Figure 2-25: Front and Back View of the Sample Model in Solibri ...... 63 Table 2-16: Tekla Structures to Solibri IFC Interoperability Result (1) ...... 64 Table 2-17: Tekla Structures to Solibri IFC Interoperability Result (2) ...... 65 Table 2-18: Tekla Structures to Solibri IFC Interoperability Result (3) ...... 66 Figure 2-26: Gantt Chart Interoperability Analysis from Tekla Structures to CPM Software ...... 68 Figure 2-27: Tekla Structures Task Manager for Producing Gantt Charts ...... 69 Figure 2-28: Gantt Chart Produced In Tekla Structures ...... 70 Figure 2-29: Gantt Chart Transfer from Tekla Structures to MS Project 2013 ...... 70 Figure 2-30: Gantt Chart Output of MS Project 2013 After Import Process ...... 71 Table 2-19: Gantt Chart Interoperability Analysis Results from Tekla Structures to MS Project 2013 ...... 71 Figure 2-31: Gantt Chart Transfer from Tekla Structures to MS Project 2013 ...... 72 Figure 2-32: Gantt Chart Output of MS Project 2016 After Import Process ...... 73 Table 2-20: Gantt Chart Interoperability Analysis Results from Tekla Structures to MS Project 2016 ...... 74 Figure 2-33: Data Import Methods in Navisworks ...... 75 Figure 2-34: Gantt Chart Transfer from Tekla Structures to Navisworks by Using MS Project 2013 ...... 75 Figure 2-35: Data Source Adding in Navisworks ...... 76 Figure 2-36: Gantt Chart Output of MS Navisworks After Import Process via MS Project 2013 ...... 76 Table 2-21: Gantt Chart Interoperability Analysis Results from Tekla Structures to Navisworks via MS Project 2013 ...... 77 ii | P a g e

Figure 2-37: Gantt Chart Transfer from Tekla Structures to Navisworks by Using MS Project 2016 in CSV Format ...... 78 Figure 2-38: CSV Import in Navisworks ...... 78 Figure 2-39: Gantt Chart Output of MS Navisworks After CSV Import Process via MS Project 2016 ...... 79 Table 2-22: Gantt Chart Interoperability Analysis Results from Tekla Structures to Navisworks by CSV format ...... 79 Figure 2-40: Gantt Chart Transfer from Tekla Structures to Synchro Pro ...... 80 Figure 2-41: Gantt Chart Output of Synchro Pro After Importing From Tekla Structures ...... 80 Table 2-23: Gantt Chart Interoperability Analysis Results from Tekla Structures to Synchro Pro ...... 81 Figure 2-42: Gantt Chart Interoperability Analysis from CPM Software to Tekla Structures...... 82 Figure 2-43: Gantt Chart Transfer from MS Project 2013 to Tekla Structures ...... 82 Figure 2-44: Gantt Chart Produced in MS Project 2013 ...... 83 Figure 2-45: Gantt Chart Output of Tekla Structures After Importing From MS Project 2013...... 83 Table 2-24: Gantt Chart Interoperability Analysis Results from MS Project 2013 to Tekla Structures ...... 84 Figure 2-46: Gantt Chart Transfer from MS Project 2016 to Tekla Structures ...... 84 Figure 2-47: Gantt Chart Produced in MS Project 2016 ...... 85 Figure 2-48: Gantt Chart Output of Tekla Structure After Importing from MS Project 2016 ...... 85 Table 2-25: Gantt Chart Interoperability Analysis Results from MS Project 2016 to Tekla Structures ...... 86 Figure 2-49: Gantt Chart Transfer from MS Project 2016 to Tekla Structures ...... 86 Figure 2-50: Warning Appeared in Navisworks Regarding Round-Tripping...... 87 Figure 2-51: Gantt Chart Output of Tekla Structure After Importing from Navisworks by Round-Tripping ...... 87 Table 2-26: Gantt Chart Interoperability Analysis Results from Navisworks to Tekla Structures by Round-Tripping ...... 88 Figure 2-52: Gantt Chart Produced In Navisworks ...... 88 Figure 2-53: Gantt Chart Output of Tekla Structure After Importing from Navisworks ...... 89 Table 2-27: Gantt Chart Interoperability Analysis Results from Navisworks to Tekla Structures ...... 89 Figure 2-54: Gantt Chart Transfer from Synchro Pro to Tekla Structures ...... 90 Figure 2-55: Gantt Chart Output of Tekla Structure After Importing from Synchro Pro ...... 90 Table 2-28: Gantt Chart Interoperability Analysis Results from Synchro Pro to Tekla Structures ...... 91 Figure 2-56: Gantt Chart Transfer from Navisworks to Synchro Pro ...... 92 Figure 2-57: Gantt Chart Produced in Navisworks ...... 92 Figure 2-58: Gantt Chart Output of Tekla Structure After Importing from Navisworks ...... 93 Table 2-29: Gantt Chart Interoperability Analysis Results from Navisworks to Synchro Pro ...... 93 Figure 2-59: Gantt Chart Transfer from Navisworks to Synchro Pro ...... 94 Figure 2-60: Gantt Chart Produced in Synchro Pro ...... 94 Figure 2-61: Gantt Chart Output of Navisworks After Importing from Synchro Pro ...... 94 Table 2-30: Gantt Chart Interoperability Analysis Results from Synchro Pro to Navisworks ...... 95 Figure 3-1: Software Packages Used In Interoperability Analyses ...... 96 Table 3-1: IFC Interoperability Analysis Results Summary ...... 97 Table 3-2: Gantt Chart Interoperability Analysis Summary ...... 98

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ACKNOWLEDGEMENTS

This thesis is a product of the kind support and assistance of many people. I would like to express my heartfelt thanks to all of them.

Foremost, I would like to express the deepest appreciation to Professor Carlo Iapige De

Gaetani, who expertly guided me all the time of research and writing of this thesis. His motivation, guidance, enthusiasm and patience kept me engaged with my research and inspired me. It was a privilege and honor to study under his guidance and I am extremely grateful to have had this opportunity.

Besides my advisor, I owe a very important debt to Professor H. Polat GÜLKAN, Professor

Gence GENÇ ÇELİK and Professor Salih TİLEYLİOĞLU for trusting, encouraging and heartening me to pursue a master’s degree at Politecnico di Milano.

I would like to express my deepest sense of appreciation to my beloved family for their encouragement, support, caring and sacrifices throughout my life. A special thanks to, Claudia

PELLEGRINO for studying and overcoming every hardship with me and not letting me give up under any circumstances. My appreciation also extends to my friends who backed me up and wished for my goodness. Without their persistent help, this dissertation would not have been possible.

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ABSTRACT

In the last decade, BIM platforms have started to be commonly used in AEC industry, because of having superiority over the conventional paper-based modeling software packages. Beside the advantages, BIM technology came up with different research topics which are generally due to the complexities faced in practice, such as measuring the efficiency of these platforms, data transfer problems among these packages and standardization.

It is incontrovertible that exchange of files is essentially required for several stages of workflow in AEC industry. In practice, a design engineer requires to exchange the project files with a planning engineer, cost analysis engineer, construction manager, project manager or consultant. To facilitate a maintained workflow between different disciplines and improve the productivity of design teams, throughout different stages of design and planning proper data exchange with full information transfer is crucial. Therefore, in the light of this solid argument, investigating and detecting the capabilities/inabilities of BIM software packages in the sense of interoperability can be informative to stakeholders who exchange data between various BIM packages.

Particularly, this thesis study includes the discussion related to interoperability analysis of different software platforms used in AEC industry. Although in theory, flawless interoperability of same type of files between different BIM platforms are ensured, in practical applications, this is not always the case. Hence, this research aims to identify imperfect data exchange of produced IFC file and Gantt Charts between various BIM software packages. Finally, the reason why this analysis was held is, to assess and show the quality of interoperability processes between the chosen commonly used BIM software packages by means of missing data, inconsistencies and conflicts to enlighten the users interested in utilization of these tools.

Because the research methodology is relevant to the interoperability analysis of IFC file and Gantt Charts, these files needed to be created and processed. In this research, four different approaches were outlined to assess interoperability of a sample 4D BIM model by IFC standard and produced Gantt Charts. Throughout the interoperability analysis of both IFC file and Gantt Charts, the following checks were examined:

If the geometrical and non-geometrical information were exchanged properly through IFC file, If the information added to the model related to time (4D model) can be read by other software packages completely, In the exchange of Gantt Charts, if all the embedded information transferred accurately.

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Furthermore, it is also useful to reveal that, regarding the software packages used in this study during the above-mentioned approaches, they are some of the mostly used in AEC industry disciplines. The performed tests include a documentation process to evaluate the completeness and quality of the geometrical and non-geometrical information identifying data- losses, conflicts and changes of exchanged IFC files and Gantt Charts.

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1. INTRODUCTION

US National BIM Standard (NBIMS-US) defines BIM as: “BIM is a digital representation of physical and functional characteristics of a facility [1].” In other words, Building Information Modeling, (abbreviated and commonly called as “BIM”) is a virtual platform where graphical and non-graphical data are produced, visualized, processed, analyzed, exchanged, shared and maintained in Architecture, Engineering and Construction (AEC) industry. The idea of Building Information Modeling system is that before building the structure physically, building it in a virtual system. So that, any problem can be foreseen, worked out and simulated, beforehand the execution phase [2].

BIM is not only a software platform used for modeling a structure, but also a process and approach allowing to follow design of a project and life cycle of the concerned structure on a virtual environment in a comprehensive way since the beginning of the concept.

Recently, the construction industry technology has started to be evolved from conventional 2D methods to 3D platforms by the commercial use of BIM tools. Increase in demand, initiatives, collaboration of different disciplines in AEC industry and adoption of BIM platforms for design entailed transferring the data between different users from variety of professions started to utilize these BIM platforms. In 2018, a research from China gives an idea about how BIM tools are utilized between different disciplines in AEC industry. The tools are most frequently used in the design stage, among the projects used BIM tools for model design (25.9%) and model checking (24.8%) respectively. These are followed by quantity take-off (16.3%), construction simulation (13.8%), construction management (7.6%), and visualization and roam (6.2%). Terrain (2.1%) and prefabrication (2.3%) are less frequently used. Only a small minority of the projects used the tools for preservation (0.5%), operation and maintenance (0.5%), and refurbishment (0.2%) [3].

Generally, working with different disciplines also means working with different types of software packages, file formats and extensions. All stakeholders (architects, engineers, designers, surveyors, contractors, etc.) working in a project, use computer applications which consume and/or supply information processed by different software utilized by other collaborators on that stage. Each software products must be able to access (insert, extract, update or modify) a subset of information created by the other one. Similarly, processed information in BIM systems must flow along the lifecycle of the project, being processed by a full range of professionals with their software packages. For a smooth workflow, “interoperability” is vital due to the properties of preventing recreation or reinput of data and to facilitate efficient use of information through the collaboration [4]. Due to this complication, information sharing influences the effectiveness of collaboration between these disciplines. Thus, the problems

3 | P a g e due to importing, exporting, manipulating, analyzing, modifying and exchanging the data between different BIM platforms arise the necessity of a common format which can be used by most of the users to allow the usability of the content from one BIM platform to another one. Once again, the term “interoperability” must be touched and emphasized to express the general idea and necessity of information exchange between platforms. Interoperability is the capability of transferring information between two or more platforms and use of the exchanged information in others in a functional way. In AEC industry, interoperability of the information is decisively important because when it is not achieved appropriately, it may end up with data- loss so that, cost over-runs and delays for the overall project.

The focus of this thesis study is “How BIM Approach is used for the Construction Management and Analysis of the Interoperability between different BIM platforms.”

In the following parts, the concept of interoperability analyses between several BIM platforms will be presented to demonstrate the information exchange efficiency and functionality of commonly used file types in AEC industry; IFC and Gantt Chart file transfers (including XML and CSV formats).

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What is Building Information Modeling? For a deeper understanding of BIM concept, another definition can be given as: Building Information Modeling is a complete virtual representation of a built facility with deep information content. It typically includes the three-dimensional geometry of the building components at a defined level of detail. Moreover, it also comprises non-physical objects, such as spaces and zones, a hierarchical project structure, or schedules. Objects are usually linked with a well- defined set of semantic information, such as the component type, materials, technical properties, or costs, as well as the relationships between the components and other physical or logical entities. The term Building Information Modeling (BIM) describes the way of creating virtual building models together with the process of maintaining, using and exchanging them throughout the entire lifetime of the built facility [5].

The main purpose of BIM use is for tasks concerning the three-dimensional model to lessen inconsistencies in the construction site, visualization of the model for collaboration of project stakeholders and preparation of preliminary schematic design [6]. In addition to this, BIM is a virtual platform not only for modeling but also for planning, constructing, controlling and managing the structure. In practice, Building Information Modeling systems can be used starting from the early stages of conceptual design, detailed design, planning and cost estimation, construction stage, operation, maintenance and management stage of the structure. In Figure 1-1, a sample 3D BIM model was given to represent how BIM software can be exploited in practice.

Figure 1-1: Life Cycle of A Project (sample building was created in Autodesk Revit 2018)

Typically, a BIM project begins relying on a 3D model of a structure depending on the purpose of use. Herein, imagining the 3D model, a design can be done with different levels of aspects. Additionally, these different levels deliver definitions and illustrations of BIM elements of various building systems at different stages of their progress and are used in the design and

5 | P a g e construction phase. This situation arises some questions to answer such as, “What is the 3D model good for? Is it just a pleasant picture or does it contain sufficient information to be fabricated and constructed in reality?”. The answer for these questions, introduces the term “LOD”. The LOD specifies the content and trustworthiness of BIM elements at different stages or milestones. The concept of LOD was established by Vico and Weber in 2005 [7].

Use of LOD concept required LOD specifications as references. The most commonly used references around the world are US system of LOD and UK system of LOD. LOD is the abbreviation of “Level of Development” in US specification and “Level of Detail” in UK specification.

In this study, US system of LOD definitions were introduced. BIMForum started to publish Level of Development Specifications in 2011. In 2019 version, LOD definitions for different levels [8] were given as:

LOD 100:

The Model Element can be schematically shown in the Model with a symbol or other generic representation. LOD 100 might be used for getting information such cost per m2, used amount of concrete and steel from Model Elements.

LOD 200:

The Model Element is schematically shown within the Model as a generic system, object, or assembly. The component contains information related to approximate quantities, dimensions, geometry, position, and orientation. Non-graphic information may also be attached to the Model Element. At this LOD the BIM elements are generic placeholders. The components can be recognized as they are represented, or their volumes for space reservation can be assumed to be right. The information obtained from LOD 200 should be considered approximate.

LOD 300:

The Model Element is graphically shown within the Model as a specific system, object or assembly in terms of quantity, dimensions, geometry, position and orientation. Non-graphic information may also be attached to the Model Element. The quantity, size, geometry, location, and orientation of the element as designed can be obtained precisely from the model. The project origin is defined, and the component is located accurately with respect to the project origin.

LOD 350:

The Model Element is graphically represented within the Model as a specific system, object, or assembly in terms of quantity, size, shape, location, orientation, and interfaces with other

6 | P a g e building systems. Non-graphic information may also be embedded into the Model Element. Parts necessary for coordination of the element with nearby or attached elements are modeled. These parts will include such items as supports and connections. The quantity, size, shape, location, and orientation of the element as designed can be obtained directly from the model without referring to non-modeled information such as notes or dimension callouts.

LOD 400:

The Model Element is graphically represented within the Model as a specific system, object or assembly in terms of size, shape, location, quantity, and orientation with detailing, fabrication, assembly, and installation information. Non-graphic information may also be attached to the Model Element. An LOD 400 element is modeled at sufficient detail and accuracy for fabrication of the represented component. The quantity, size, shape, location, and orientation of the element as designed can be measured directly from the model without referring to non- modeled information such as notes or dimension callouts.

LOD 500:

The Model Element is a field verified representation in terms of size, shape, location, quantity, and orientation. Non-graphic information may also be attached to the Model Elements. This level is related to field verification and is not a representation of progress to a higher level of model element geometry or non-graphic information.

An illustration regarding the different LOD levels was given [9] in Figure 1-2:

Figure 1-2: Different LOD Levels

BIM is an object-oriented database of the structure with an augmented coordination of construction documents in which geometry, spatial properties and the characteristics of structure components are provided. The elements created in BIM are labeled as intelligent

7 | P a g e objects because they contain information linked with their real dimensions. The property “intelligence” is inserted into the elements by embedding the building characteristics that describe the elements of placed objects which have a relationship to one another [10]. Presence of intelligence in BIM software packages make them privileged over traditional methods. In this point, a special attention should be paid to reveal differences between BIM platforms and Computer Aided Design software packages. Different from 2D CAD drawings, BIM models are composed of “parametric objects” in which their parameters can be specified with user-definable equations. This property of BIM makes the objects interactive with each other. These smart objects are composed of geometrical and non-geometrical data together.

Additionally, BIM objects are different than conventional CAD drawings, in the sense of self- adjusting themselves according to the manipulation of users to provide the previous interaction and containing also the non-geometrical data. On the other hand, CAD software packages contain only graphical data but not non-graphical data which can be material density, producer information, strength, maintenance procedure, etc. A practical comparison to emphasize geometrical differences of BIM objects and CAD drawings can be given as, in a BIM platform, when the user changes the roof elevation, the walls connected to the roof change their height or else a door is placed to a wall, the needed space is adjusted by the software itself and without any need of change all the drawings and quantities related to that object redo again automatically.

Another aspect of defining BIM models is to characterize them with various dimension numbers according to the data included to describe a model. Typically, the types of data which are used to create a model are named as “Dimension”. BIM dimensions are specified as ‘nD’ modeling as it has the capability to include an almost infinite number of dimensions to the Building Model [11].

In general, the following dimensions are considered in a model:

3D model is the object model which describes the geometry, locations and orientations of elements and components. 4D is the dimension including information related to planning which connects the construction tasks represented in time schedules with 3D models. They are handy for performing real-time graphical simulation of construction progress for specified time. Having the 4th dimension ‘Time’ allows to evaluate buildability of the structure in a specified time period and review workflow planning of a project. Project stakeholders can effectively visualize, analyze, and communicate problems regarding sequential, spatial and chronological

8 | P a g e aspects of construction progress. Therefore, much more rigorous schedules, site layouts and logistic plans can be produced to enhance productivity.

Addition of ‘cost’ information to the BIM model produces the 5D model, which allows the quick analysis of cost budgets and financial representations of the model. This function of BIM significantly lowers the time spent for quantity take-off and preparation of bill of quantities. It also improves the accuracy and trustworthiness of estimates, by reducing the possible errors due to the use of ambiguities in CAD data with spreadsheet. Thus, it is clear that 5D BIM provides positive impacts to cost managers/engineers by reducing the time spent in cost estimation and allow them to spend more time on value improvement [12]. Another BIM dimension integrates sustainability to the related model and is labeled as 6D BIM. It allows designers to perform specific energy analysis of the project and meet requirements to validate the design decisions appropriately or test and compare diverse sustainability solutions. Lastly, 7D BIM models stands for facility management. The core BIM model is a rich description of the building elements and engineering services that provides an integrated description for a building. This feature together with its geometry, relationships and property capabilities emphasizes its use as a facility management database.

In BIM terminology, the data form the 4D to 7D BIM dimensions are non-graphical and they are labeled as “information”.

All the BIM model dimensions more in detail can be expressed as:

3D BIM

3D BIM is the well-known dimension of among the others and assembles the graphical data and illustrates the visible parts of a BIM model. These parts represent the information regarding the geometrical data. One can exploit the 3D BIM model output regarding these benefits:

i. Project visualization, ii. Model verification with the standard requirements, iii. Virtual mock-up models, iv. Model Walkthroughs, v. Clash detection, vi. Prefabrication details.

In practice, 3D BIM models are used by various disciplines which are architects, structural engineers, contractors, sub-contractors, suppliers etc.

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Use of 3D BIM models is efficient because it comes up with some benefits which provide improved quality of the project, compatible work of different disciplines involved in design and reduced errors and rework.

4D BIM

The 4th dimension of BIM is “time” and it is added to the 3D model. In practice, the 4D modeling is also called model-based scheduling [13]. Intrinsically, because they contain the information regarding scheduling, 4D BIM models (in Figure 1-3) are used to track the project progress with respect to time. In 4D models, complex projects are planned and visualized as a whole or just some phases of it. Additionally, during the construction, 4D BIM model allows users to follow the actual schedule and planned schedule. Thus, any possible delay can be identified before starting the construction.

The information obtained from these models can be used to plan the construction activities such that, start/finish date, duration, sequence of each tasks, identification of gaps and overlapping tasks. Obviously, planning of these tasks allows the engineers to manage the necessary construction equipment and materials, site logistics or workers before starting the task. For instance, in a 4D model, it is possible to follow, when a crane will be set, and demolished or which part of the construction work is ahead or behind of the plan.

As a summary of what BIM 4D model allows its user to:

Spatially visualize the construction sequence by identifying possible hinderances between the stock and access areas, as well as other elements of the construction site, Test different options in sequencing by foreseeing possible problems in construction site within the planning phase, Assist the construction team to coordinate the workflow and the use of the construction site, allowing collaborators to operate in a safer environment and more productive conditions which contribute to more feasible and faster construction, Compare the progress by dates and the construction flow, which makes it possible to monitor whether the project is on time or behind schedule, Increase the probability that the building will be concluded and delivered according to its planning and project [14].

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Figure 1-3: 4D BIM Model View from Synchro Pro

5D BIM

It is well-understandable that precise cost estimation during the early stages of construction projects is crucial. In the past, cost assessment was based on user’s experience because the cost estimation is the prediction of cost for a process or project using experience or methodology. Any mistake done in cost estimation phase causes in accurate decision making, so that, this may lead to catastrophic cost overruns or project delay. Early development of project cost estimation is a key factor in business unit decisions and often becomes the basis for a project’s ultimate funding [15].

5D BIM dimension consists of “Quantity Take-Off” which means the extraction of measurements and material quantity for each element. Hereupon, the unit price of each element is assigned to the extracted measurements and quantities. As a result, cost of each item and total cost can be found. 5D BIM is used for budget tracking and cost analysis of the construction. The data in 5D BIM might include:

i. Capital costs, ii. Its associated running costs, iii. The cost of renewal/replacement of elements.

In practice, an engineer responsible from the cost analysis can approximate the expense strategy and cost of the structure very quickly, accurately and even with different combinations.

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6D BIM

This dimension of BIM helps to perform energy analysis of the structure in the early design phase. The 6D dimension of BIM indicates “sustainability” and it refers to sustainable construction, which seeks the contribution of the built environment in the sense of sustainability and focusing the ecological, social, and economic issues of a building in the framework of its community [16].

6D BIM should allow to perform these analyses: prediction of energy consumption monthly or annually, estimate of CO2 emission of the building and set solutions to reduce carbon footprints and provide various energy efficiency alternatives.

7D BIM

The information associated to the operation and maintenance of the facility throughout its life cycle is assessed in 7D BIM.

In 7D BIM, the database should be enriched with detailed information for each embedded element: structure itself, finishing and all equipment (HVAC, lamps, elevators etc.). The relevant information embedded can be type of the element, its description, the time of the maintenance or replacement, the warranty period, the time consumption. This will allow for appropriate and planned maintenance of the building. Additionally, in case of any failure in one element, it will be able to be quickly located the item and repaired or renovated [17].

The BIM maturity describes levels of maturity with regards to the ability of the construction supply chain to operate and exchange information [18]. The maturity levels in UK developed by Mark Bew and Mervyn Richards explained in the following Figure 1-4 [19]:

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Figure 1-4: Maturity Levels by Bew and Richards

BIM levels of maturity can be expressed more in detail:

Level 0

This level of maturity does not include any collaboration between stakeholders gathering information about a structure. Likely, the data processed in this level consists of 2D drawings and exchange of paper-based drawings. It is the conventional working practice.

Level 1

This maturity level may cover 2D and 3D modeling of the structure for visualization and concept development models. The models are not shared between the project team members; however, individual file exchanges are performed across the various project members.

Level 2

The models of each design team member are assembled to create a merged model. By the concept, the merged model is called “federated model”. This level is characterized by allowing collaborative working to all parties. The usage and adoption of BIM in all UK government acquired projects with a Level 2 BIM status is mandatory by April 2016 [5].

Level 3

In the construction industry Level 3 BIM Maturity Level is a target to reach. Its main point is the achiving full integration (iBIM) of the information in a cloud-based environment.

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This level integrates all the disciplines by allowing a single-shared model for the project and provides full collaboration between design team members.

Due to the advantages of BIM such as: visual improvements in modeling, improved productivity of disciplines, reduction in costs, etc. today, number of countries adopting BIM packages is increasing rapidly all around the world.

In 2016, the European BIM market was estimated as EUR 1.8 billion and is expected to grow by 13% to be EUR 2.1 billion in 2023 [20]. In 2015, a research showed that, in Europe, 29% of construction firms use BIM 3D, while 61% have never used it. The numbers worsen concerning BIM 4D with only 6% of companies implementing it [21]. Obviously, today these rates of companies use BIM is expected to be higher than 2015.

To cover the topic of “BIM Adoption in the World”, some countries were selected from different continents and presented:

United States

BIM application was initiated in the beginning of 1970s in US, though the progress of BIM has slowed down [22]. The US General Services Administration (GSA) anticipated 3D and 4D BIM Program way back in 2003. This program empowered BIM adoption for all the Public Buildings Service Projects. Gradually, BIM adoption is increasing its recognition in the United States and has definitely impacted on the AEC industry. United States owns 72% of BIM adoption by the construction companies [23].

United Kingdom

In BIM use, UK has an important role compare to the other countries. It is widely recognized as a world leader in adoption and BIM standards.

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Figure 1-5: BIM Adoption Rate Between 2011-2019 in UK

As it can be seen from the Figure 1-5 retrieved from [24], the results show the adoption rate of building information modelling (BIM) in the United Kingdom construction industry between 2011 and 2019. By 2019, 69 percent of industry professionals reported using the tool.

Additionally, it was also reported that, BIM was mandated in the UK since April 2016 in every construction and the entire government project are held on BIM Level 2.

Italy

Italy is also one of the countries which developed regulations for the implementation of BIM.

For instance, D.lgs. n. 50/2016 (“Codice degli appalti”) including the progressive adoption of digital methods and electronic instruments such as Building and Infrastructure Information Modelling”.

Decreto BIM (D.M. 560/2017) published on 12/01/2018 by the Ministry of Infrastructure and Transport website, establishes the implementation dates of the BIM in the public procurement contracts, according to a progressive schedule.

In 2017, UNI 11337-1, UNI 11337-4, UNI 11337-5 and UNI 11337-6 have been published. UNI 11337-3 was the Italian National norm which firstly introduced the BIM Concept.

Turkey

In Turkey, there are leading attempts for adoption of BIM because of fulfilling the need in the future growth of Turkish construction industry.

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Use of BIM systems has been increasing in Turkey in recent years. Even though, the increment of BIM adoption is slower than developed countries there are many academic researches, initiatives of design offices and certificate foundation usage. So far, there is no legal regulation regarding the use of BIM, however in the near future, adoption of Turkey to the BIM system should be ensured and standardized [25].

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BIM for Construction Project Management In the last decade, there was a misperception about how to utilize BIM packages in AEC industry. The most common misunderstanding was that treating BIM systems as a technology which helps to create only 3D models and creating shop-drawings and turning a blind eye on the processing and/or managing information capabilities of them.

Using this innovative method in AEC industry provides some benefits to users such as better- quality of the construction works by delivering enhanced details of 2D and 3D views, better rapport between designers and construction workers, improved productivity, time and cost savings, avoiding structural clashes or inconsistencies, better communication between design team members and with the stakeholders of the project, having a better control on the construction cost and schedule, devising more sustainable solutions and good maintenance of the facility after the construction is completed. All these developments and utilities made BIM technology more demanded and widely held by governments, companies and individual users in the last decade.

In AEC industry, companies are always dealing with providing satisfactory projects even with minimal budget and manpower, sticking to a tight schedule and conflicts between stakeholders. The solution for these construction management problems can be found by creating better communication environment between architectural, structural and MEP disciplines and in this point, BIM has an important role to play.

In construction management, the model created in BIM can be exploited in different ways according to the purpose of use. In 2015, a research [26] showed BIM practices in construction application areas with rates of use in China was given in the following Figure 1-6 below.

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Figure 1-6: BIM Use in China Related to Application Areas

In the following, some contributions of BIM to construction industry was discussed:

Preconstruction 3D Project Visualization

The entire project can be visualized during the design stage, before starting the construction. This function allows owners to inspect the 3D views of the structure and gives opportunity to make some changes in the design. This property of BIM has a greater impact in the beginning of the design, and it appreciably minimizes costly and laborious changes later.

Clash Detection

A structure has thousands of components which spatially depend on each other. The layout of these components must be considered wisely to prevent any clash between them [27]. However, it may not be always possible to avoid from these clashes. In the early design stages, it is crucial to detect any MEP, internal or external clashes before the construction begins. In BIM software packages, it is possible to resolve the clashes in a short amount of time without changing many details.

Increased Productivity and Prefabrication

After completing the 3D model, BIM data can be used to obtain drawings and information regarding the manufacturing purposes. Because 3D models can also include the information related to the material type, finishing and cross-section properties, use of BIM in production is very convenient. Specifically, in precast and steel structures, the structural components can

18 | P a g e be designed and detailed for offsite production, so that, use of BIM in these types of structures much more efficient in the sense of increasing quality, reducing labor and material cost.

Model-Based Cost Estimation

Cost estimation should be performed to calculate budget prices based on a schematic design, however, since a schematic design only provides rough estimation, it may be difficult to obtain enough information needed for cost estimation. For example, finishing material and finishing thickness can be obtained from a schematic design, but detailed information such as the specific material type and the construction method type cannot be obtained. Thus, a cost estimator implies these details from work conditions. Inevitably, a cost estimator's decisions become involved in the cost analysis [28]. However, in model-based cost estimation as the information regarding the cost of each item was assigned to the model, it is possible to analyze the cost of each item separately and concluding total final cost. So that, 5D BIM concept meet the requirements for more precise cost estimation by model-based cost estimator function.

Improved Scheduling/Phasing

The main idea of scheduling is to sequence each phase of the construction works in a timeline and the corresponding process of the scheduled use of resources. In the schedule, it has to be ensured that not only construction period is congruous with the contract, but also it needs to make the final project reliable, secure, applicable, satisfactory, no quality defects while minimizing construction costs and achieving the target profits without exceeding the budget price of the contract [29]. Conventionally, construction steps are shown in Critical Path Method or Gantt charts. However, these methods are not adequate to simulate all construction process due to the lack of linking the different sequences to each other, not including resources and restraints of the construction. In 4D BIM, scheduling/phasing information can be included in the model by embedding elements to each task in Gantt Charts or assigning phases to the elements in the model. Though, combining BIM tools and Gantt Charts, construction steps can be followed progressively.

The advantages of 4D BIM over traditional construction management methods can be expressed as follows [29];

In a three-dimensional model each defined phase of construction can be displayed, modified and operated in 2D or 3D view, Due to the integrated model in BIM environment, it is easy to perform clash analysis before the construction starts, so that the problems due to the collision of different elements can be predicted during the planning, scheduling or phasing process,

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In BIM environment, it is possible to achieve real-time comparison and monitoring between resources and costs, During the construction process the information related to project quality or safety problems can be documented on the 3D model in a virtual environment for the record.

Initial use of 4D models were started in 1980s by manually combining snapshots to each phase of the construction process to the 3D models. In 1990s, some commercial software packages was released with capability of directly connecting the 3D model to the construction phases [30].

A 4D model allows to follow each single step of construction with specified durations and start/end dates of tasks, even with an animation which makes tracking of activities a lot easier compare to traditional Gantt Charts. 4D models are very handy tools that improve communication between planners, designers and stakeholders of the project. As well, in 4D models, it is also possible to arrange the site area in planning stage such as, placement of the resources or settlement of a large equipment used in construction such that, cranes or scaffolds, can be planned before the project starts.

Collaboration and Communication

The process of design and construction requires collaboration and communication of design, engineering and consultancy teams. Collaboration and communication are necessary in AEC industry due to the need of problem-solving, evaluating the work done, giving feedbacks and suggestions. In traditional methods, the collaboration between the stakeholders have relied on 2D drawings, paper-based reports, telephone calls and physical meetings. In a virtual environment provided by use of BIM software collaborating, sharing and performing different operations by different design teams are possible. BIM seeks to allow stakeholder’s collaboration at different stages of the building progress, supporting stakeholders to insert, extract, update, modify and exchange information during the BIM process [31]. Working in a virtual environment ensures the use of interactive drawings, exchange of files regarding design and collaborating with different professions all through the process, simultaneously. Generally, collaboration and communication are ensured by file exchange of 3D model, schedule and cost estimate information.

Most of the BIM systems support exchangeable structure models in a neutral format. In practice, the most commonly used ones are IFC, DWF and VRML. These formats are easy to produce, process and exchange between users.

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Interoperability The need of data exchange in AEC industry arises due to the contribution of different participants to design stage and construction process of structures during the workflow. Because there are many different disciplines involved in this industry, variety of different software packages are available to perform variety of tasks, i.e. creating 3D geometry of structure, performing structural analysis, cost estimation and planning, operating the facility [32]. Moreover, there is no single software to do all these tasks, hence, use of more than one single software is a must. The software packages in the market do not support or have limited support exchanging the information. Thus, while performing analyses from one tool to another, due to the incompatibilities in file exchange, additional exertion is generally required. Consequently, the traditional methodology to share the data reduces efficiency of users and increases risk of losing information or wrong processed data.

Today, there are several exchange formats frequently used in AEC industry such as: DXF, DWG, XML, SAT, STP, 3Ds, and IFC or CIS/2. A research [31] showed that, mostly used files in AEC industry are .pdf files, Microsoft Office package files, AutoCAD files and IFC files. The results of the survey including the mean and standard deviation of the participants can be seen in following Table 1-1, retrieved from [31]:

Table 1-1: File Exchange Formats Used in AEC Industry

Each of these file formats have certain capabilities. For example, DXF (Drawing exchange format) and DWG files are generally used to exchange the technical drawings in 2D CAD files but cannot be used for 3D drawings. Another example is that, a software which can process .3Ds file format, may not process IFC standard. Therefore, the need of a common data standard arises to deal with these practical challenges. In addition to this, throughout the

21 | P a g e exchange operations, the file format versions must be taken into account, even if the file standards are the same, this is due to the fact that, new updates in versions may cause conflicts. To solve these problems, while addressing the exchange operations, it is necessary to describe the term “interoperability”. The Institute of Electrical and Electronics Engineers (IEEE) defines interoperability as “The ability of two or more systems or components to exchange information and to use the information that has been exchanged”.

Focusing on BIM systems, it is known that the interaction is allowed between various users in virtual building simulations. When it is needed to change the components of the 3D model, a common connection and source of communication in BIM systems are required. This connection is achieved by interoperability of various models that may have been produced by different software packages. There are significant attempts to develop standards to set interoperability between these systems to make them compatible with each other. This leads that, for a model being compatible with models created by other software tools, it is crucial for all of them to be translatable into a file format, so that, all the information of the object can be transferred properly [33].

The success of interoperability in 3D model-based data between two different users can be assessed by the following criteria [34];

The execution of the export and import translator functions inserted in BIM tools, The internal structure of the neutral file format supported by the BIM tools, Lastly, the variety of data object types to be shared.

BIM software packages are advantageous in the sense of improving the quality of interoperability between them. The benefits of BIM due to the enhanced file exchange operations are having no need for data-entry manually, reducing the errors due to the re-entry of data, saving time, and increasing efficiency of the users. A practical example was given in [35]; BIM systems allow the coordination inside only one 3D model and which makes BIM tools better than exchanging and processing several 2D representations with different software groups. Herein, any possible mistake can be avoided in a way that, decreasing the human error, design and production costs. Consequently, the information sharing is better, faster, and secure.

In general, the issues related to interoperability in BIM projects are mostly solved with a standardized file exchange format i.e. Industry Foundation Classes (IFC) which was first specified in 1996 by the International Association for Interoperability (IAI) and developed by the BuildingSMART International [22]. As it is described in website of the BuildingSMART the definition of IFC is: “In general, IFC, or "Industry Foundation Classes", is a standardized, digital description of the built environment, including buildings and civil infrastructure. It is an open,

22 | P a g e international standard (ISO 16739-1:2018), meant to be vendor-neutral, or agnostic, and usable across a wide range of hardware devices, software platforms, and interfaces for many different use cases [36].” IFC indicates “HOW” information is to be exchanged. It is one of the public and worldwide accepted standards (ISO/PAS 16739:2005) for exchange of information in the AEC industry [11]. IFC adopts ISO-STEP EXPRESS language to describe its models. Objects defined in the IFC data model allow the sharing of intelligent information included in BIM [33].

IFC file format has the possibility to indicate the information about design, engineering and production process. More in detail, IFC represents the geometry, relations, properties of the structural elements and meta-properties for information management i.e. data about reinforcement types, concrete class or finishing detail of slabs, etc. Today, commonly used BIM tools support import and export of IFC files and they are capable of processing it. However, AEC industry is a huge field of works and it may not be expected from IFC Standard to specify everything in building construction. Therefore, it is a challenge for software developers to imply the full IFC specification because of poor documented and huge number of classes, or even a restricted subset as defined by the relevant View Definition. It is usual to face with misinterpretations of the standard or IFC functionality not repaired sufficiently by software developers [37]. The problems faced in this point would not have an important effect on interoperability if a valid IFC certification process were in place. The certification is done by BuildingSMART which tests the software with series of simple cases. After passing the first part of testing, applications are intended to be tested by end-users during a half-year period and if they are considered of enough feature and capability, they are tested again with data sets from real projects. Even though the testing process is complicated, the process cannot ensure the quality of IFC import/export capabilities of any software [38]. Today, the most updated official release of the IFC specification is IFC4.1 that was release in June 2018 and IFC4.2 is named as candidate standard which was published in April 2019 [39].

Because IFC file format has extensive data structure, it is possibly used in any data exchange scenario during the lifetime of the structure. IFC standard is developing more due to the initiatives from all around the world in national and international level. The pioneer countries can be given as, United Kingdom, United States, Singapore, Finland, Denmark and Belgium. Additionally, most of these countries apply some regulations for the use of IFC standard in public projects.

XML is another type of file format which was used in this thesis study for exchanging produced Gantt Charts. This is an alternative way of exchanging data. XML file format develops upon HTML by providing user-defined codes to specify a data transmitted. Main use of XML is to

23 | P a g e exchange data between web applications. Additional to XML file transfer while exchanging Gantt Chart, CSV file format was also utilized and explained in the further parts of this study.

In Section 2: INTEROPERABILITY ANALYSIS part, exchange operations of IFC file and produced Gantt Charts will be performed and analyzed based on a sample model.

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2. INTEROPERABILITY ANALYSIS

For the purpose of this study, interoperability analyses were performed by choosing different software packages which are commonly used in AEC industry to imitate the real-life engineering problems throughout various exchange operations of files.

The important point in exchange operation among different software packages is that, even if they are used for achieving similar tasks and include analogous functions, they may offer various ways to define an object or a task. So that, created elements in one BIM software may not be successfully exchanged to another BIM software with full functionality and complete data. If one considers how the design and construction works are proceeded, it is explicitly understandable that during exchange of files, any data loss including material type, scheduling or phasing information, cost of elements or 3D data related to fabrication and production, can be concluded with loss of quality, ineffective teamwork, cost overruns and time delays due to data loss.

As mentioned before, the chosen software packages are some of the commonest used in AEC industry. For the coherent representation of workflow between model designers and construction project managers or planning engineers, the software packages used in this thesis study have been divided into three groups according to their features. The software groups were given in Table 2-1:

Construction Project Design Software IFC Viewers Management (CPM) Software

Autodesk Navisworks 2019 Tekla Structures 2018i ACCA usBIM.viewer+ Synchro Pro

Microsoft Project 2013 ACCA Edificius Solibri Model Checker Microsoft Project 2016

Table 2-1: Software Packages Used in This Study

For better understanding of the concept, it is necessary to point out the differences and capabilities of these software groups and their specializations. The first group software packages are named as “Design Software” and generally used for designing and developing a BIM model in practice. It is composed by Tekla Structures 2018i and ACCA Edificius.

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Tekla Structures which is offered by the Finnish company Tekla Corp. which was founded in 1966. Their first software “Tekla Xsteel” was presented in the 1990s [30]. In 2011, the company was bought by Trimble Inc. [40].

Tekla Structures is one of the most developed and commonly used BIM software in AEC industry which allows users to design, associate, manage and collaborate in 3D environment for different tasks. This software can be used from the very beginning of the project by directing design, fabrication, construction and detailing process to the end of service life of the structure by providing additional information for maintenance for different users from different professions.

Nowadays, Tekla Structures software is sophisticated enough to create precise, comprehensive data stored, manageable in every stage of life-cycle model. Additionally, according to use of purpose, the highest level of development (LOD-500 in US scale of LODs) can be implemented with this platform.

Tekla Structures is a strong tool which is equipped by versatile ability of introducing all kinds of construction materials, detailing and designing complex structures. Therefore, designers can manipulate huge and detailed models with other synchronized users.

It was already strongly emphasized that, one of the important tasks of BIM software is, to allow coherent work of different professions together. So that, as also it is one of the main issues discussed in this study, file importing and exporting, linking the data between different software packages can mostly be performed in Tekla Structures. It allows to work with IFC, DWG, CIS/2, DTSV, DGN file extensions [30].

Next BIM tool which was used for this study is called ACCA Edificius. It is a software which is developed by the Italian ACCA company founded in 1989. It is used to create architectural model of a project, schedules, cost output, renderings and videos of the project including virtual reality. It raises the productivity of design teams by having Real Time Rendering option and integration with other ACCA software packages. It allows the collaboration in the BIM process with certified IFC interoperability [41].

Second group was defined by the “IFC Viewers”. The software packages in this group are used for model checking, displaying model and reviewing semantic data embedded in BIM models.

ACCA usBIM.viewer+ is a powerful tool to view, convert and edit IFC files in a single software. It allows to open an IFC file produced with any BIM Authoring applications. Moreover, it is also possible to view all the IFC objects and work on them by modifying properties or geometries [42].

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Solibri Model Checker is another tool which was used in this study. It is a product of Nemetschek Company based in Finland. Similar to ACCA usBIM.viewer+, Solibri also supports IFC file exchange. In Solibri, it is possible to check IFC Models, review design, process coordination, etc. [43]

Because both software support IFC format and are commonly used in AEC industry, it was preferred to use them also in this study to be more comprehensive.

Focusing on group “Construction Project Management (CPM) Software”, it is composed by tools used mostly in construction project management and reviewing models. In practice, these software packages are used by project managers, consultants and planning engineers.

Starting from Autodesk Navisworks, it is a tool to review 3D models for architecture, engineering and construction. Additionally, it allows to perform clash detection analysis, collaboration of design teams, project model coordination, scheduling (4D-time simulation) and 5D analysis. It can also be used to combine the design and construction data into a singular model. Moreover, for the purposes where high-quality images of the projects needed, it is also used for photorealistic rendering.

Another BIM tool is Synchro PRO which also have similar functions like Navisworks. It is a BIM tool for 4D scheduling and construction project management. Synchro PRO can associate the construction resources such as human, material, equipment and space to the related tasks. It is usually used by contractors, subcontractors, suppliers and consultants.

Another software package used in this study was Microsoft Project. It is a tool to manage projects in terms of schedules. In Microsoft Project, it is possible to export/import in CSV, XML, XPS and PDF file formats. This feature makes this software very handy for construction project management tasks throughout creating, processing and exchanging Gantt Charts. MS Project is also very robust tool in the sense of being compatible with different BIM software. In this research, MS Project 2013 and MS Project 2016 versions were available and utilized for research purposes.

The main difference between these three groups of software packages is that first group packages are used to prepare model of a structure, detailing the structural elements or creating structural plans, second group is mainly utilized for viewing models and managing embedded information in the produced model and the last group is more focused on the production of schedules and preparing project management tasks.

Because in this research the exchange operations of produced IFC file between various BIM packages examined, it is necessary to point out that IFC data format is supported by most of the used software packages. For comprehensive and proper use of IFC, there must be a robust

27 | P a g e implementation in software available to users in their respective regions and marketplaces. BuildingSMART provides certification for the tools in BIM industry to validate use of IFC. In this study, Tekla Structures, ACCA Edificius, ACCA usBIM.viewer+ and Solibri Model Checker software are IFC 2x3 certified [44].

Furthermore, another interoperability analysis was also performed on the basis of importing/exporting different Gantt Charts in each software and the quality of the exchanged data was assessed. In this process, the exchange of Gantt Charts between these packages were performed in XML or CSV format when it was required by the used software. XML is the abbreviation of Extensible Markup Language and it defines set of rules to encode machine and human readable documents. A markup language is a computer language which uses tags to define elements. On the other hand, CSV is also called as “comma-separated values” and contains tabular data.

In this research, four different experimentations were assessed. Noting that, the first methodology was labeled and presented as “BIM Interoperability Through IFC Standard” and discussed in Section 2.1. The analysis was performed by investigating if 3D and 4D information could be transferred via IFC file properly. The methodology for this experimentation follows these main steps and can also be seen from Figure 2-1:

1. The sample 3D model was built in Tekla Structures. 2. The 3D model was divided into different phases which represent construction sequence of each structural element and finally a 4D model was obtained. 3. The obtained 4D model was exported in IFC format from Tekla Structures. 4. The IFC file was imported into another software (ACCA Edificius, Navisworks, Synchro Pro, usBIM.viewer+ and Solibri Model Checker) to be tested in the sense of detecting missing or conflicting schematic or meta-data information including the phasing.

Figure 2-1: Workflow for Interoperability Analysis Through IFC Standard

Second experimentation includes the assessment of Gantt Chart exchanges produced in Tekla Structures and imported to Construction Project Management software. It can be named as

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“Gantt Chart Interoperability Analysis from Tekla Structures to Construction Project Management (CPM) Software” and discussed in Section 2.2. of this study. The followed methodology can be expressed in this way and also seen from Figure 2-2:

1. The structure was divided into different tasks in Tekla Structures by using Manage>Tasks command. 2. For each task, generic start and end dates were assigned with duration of the relevant task. 3. After creating all the tasks, a Gantt Chart was obtained. 4. Created Gantt Chart was exported in XML format. 5. The obtained Gantt Chart file was imported into all Construction Project Management (CPM) software packages.

Figure 2-2: Workflow for Interoperability Analysis of Gantt Chart from Tekla Structures to CPM Software

The third one can be considered as reverse way of the second experimentation. This experiment is presented as “Gantt Chart Interoperability Analysis from CPM Software to Tekla Structures” in Section 2.3. The way it was performed can be followed from given steps below and Figure 2-3:

1. Gantt Charts were created in each software of “CPM Software Group”. 2. Each produced Gantt Chart was exported in XML format. 3. The obtained XML files were imported into Tekla Structures.

Figure 2-3: Workflow for Interoperability Analysis of Gantt Chart from CPM Software to Tekla Structures

Last experiment in Section 2.4. discusses how the Gantt Charts can be exchanged between various CPM software and it was performed only with third group (CPM) software packages. This experimentation is called as “Gantt Chart Interoperability Analysis Between CPM Software”. The methodology includes the steps below and was shown in Figure 2-4:

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1. A simple Gantt Chart was produced in CPM Software (1). 2. The produced Gantt Chart was exported 3. Exported Gantt Chart was imported into CPM software (2).

Figure 2-4: Workflow for Interoperability Analysis of Gantt Chart from CPM Software (1) to CPM Software (2)

Including all these experiments, the key questions to answer were:

How much data can be exchanged from one tool to another? Can 4D Model be exchanged between various BIM software packages by use of only IFC without losing any detail or data conflict? How about the quality and processability of the data transferred? Which quantities were exchanged or could not be exchanged? What are the basic changes in Gantt Charts after performing export and import operations? How much the adverse effects of the lost data for the collaborators?

The 3D Model developed with Tekla Structures and was used as reference can be seen in Figure 2-5 and Figure 2-6 in 3D.

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Figure 2-5: Front View of Reference Model

Figure 2-6: Back View of Reference Model

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As it can be seen from the Figure 2-5 and Figure 2-6, the geometry of the model is well-defined. More in detail, the structure is a building with three upper floors with a flat roof and one basement which is at 2.60 meters depth. The height and the length of the building are 9.10 meters and 19.00 meters, respectively. The quantity, dimensions, shape, material type, location and orientation of the elements are included in the model. Some structural element details such as the stairs, including also the steel one where the bolts and welds are clearly defined and types of the bolts are given, too.

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BIM Interoperability Analysis Through IFC Standard It is known that, in practice, interoperability of same type files between different software packages is not always flawless and continuous throughout the workflow. To examine this phenomenon, in this part of the study IFC Standard use was exploited. The initial point of this study was to create phases for all the elements in Tekla Structures. The idea of adding phases was to identify how the different phases will be exchanged from one BIM tool to another. Additionally, creating phases is also useful to produce Gantt Charts, so that, while creating Gantt Charts, it is easier to assign them to the related task.

Figure 2-7: Expected Flawless Interoperability Through IFC Standard

In IFC interoperability analysis, 3D representations (i.e. geometry, dimensions) and distinct characteristics of structural elements, (i.e. material properties, finishing details etc.) and 4D information which was embedded in the model by use of phases were examined to validate if 4D model can be exchanged appropriately.

To obtain the relevant 4D model, during the phasing stage the main concern was to be precise and accurate while assigning each phase to an element. It was an important task because for proper assessment of performed tests, any missing data relevant to the phases could be misleading for this study. In addition, phasing names were chosen according to the relevant tasks supposed in a sequential way.

In Tekla Structures, Phase Manager can be reached by Figure 2-8 and the output can be seen from Figure 2-9 below.

Figure 2-8: Phases” in Tekla Structures to Add Phase Information to 3D Model

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Figure 2-9: Phases Produced in Tekla Structures

These phases include various complex geometries of structural elements and were used for benchmark tests in assessment and review of 4D Model in further parts. Each phase indicates the construction of specific elements. The construction sequence can be followed from this output. Finally, after completing the creation of phases for each task, 4D model was obtained in Tekla Structures. The related representation of each phase was given in Table 2-2 and Table 2-3.

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Table 2-2: "Phases" Created in Tekla Structures (1)

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Table 2-3: "Phases" Created in Tekla Structures (2)

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For this research, initially, some repetitive elements (i.e. choosing one specific bolt element to represent all bolts or choosing one specific panel wall to represent all panel walls, etc.) were selected from Tekla Structures. Afterwards, their 3D representations in another BIM software were investigated by visual inspection to identify any schematic conflict or data-loss in each element. Additional to the 3D representation check, an assessment was also performed by use of embedded phase information to detect any conflict, missing data or change in the 4D Model during IFC exchange operations from Tekla Structures to another BIM software. As a summary of this procedure of IFC analysis, the main principles of assessment can be listed as below:

Is the geometry of the elements the same or changed by exchange of IFC file? Can all the 3D elements be transferred completely? Is the assigned phase transferred appropriately with all the related elements to justify 4D Model exchange? Can all the properties regarding the element characteristics be transferred or not, such as material type, density, area, volume, etc.?

Even though, Tekla Structures software is capable of exporting various types of files such as: CAD, SketchUp, 3D DGN, 3D DWG/DXF, for this study, it was necessary to export the sample model in IFC format. Before starting the analysis, it is useful to mention how the IFC export was performed in Tekla Structures. By using the commands: “Menu>Export>IFC”, IFC export was concluded, as in Figure 2-10.

Figure 2-10: IFC Export in Tekla Structures

Herein, there are some points which require special attention. In IFC export, Tekla Structures, provide several IFC export options. For example, “Coordination View 1.0”, “Coordination View

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2.0”, “Surface Geometry” and “Steel Fabrication View”. Each of these export types has their own settings.

“Surface Geometry” option is ideal for design coordination and purpose of view. “Steel Fabrication View” is preferred to export detailed information for steel fabrication. “Coordination View 2.0” is advised for software that has the IFC Certification 2.0, and when the sample model includes reinforcement. The Coordination View 2.0 focuses on the coordination of architectural, structural engineering and building services tasks in design phase. The import and export of IFC files in Tekla Structures conform to the IFC2x3 Coordination View Version 2.0, and the IFC2x3 import and export certificates have been granted [45].

In this study, the compatible format chosen was “Coordination View 2.0” because it was more complied with purpose of use. More in detail, the settings for this option can be listed as [46]:

Reinforcing bars as extrusion, Constructive Solid Geometry (CSG) support on, Curved elements as RevolvedAreaSolid, Bolts as B-rep.

Obviously, flawless translation and readability of the model in imported BIM software is essential, not only for architectural or design purposes and also in the sense project management.

For the assessment of IFC interoperability, between all the attributes which a user can define in a BIM software for a structural component, the chosen parameters are the mostly considered and commanding ones. These parameters that were used in this study can be given as: “Name”, “Geometrical Properties”, “Material Type” and “Phase Number”.

Herein, to emphasize the significance of the chosen parameters, they are the ones mostly exploited in 4D BIM models and construction management tasks. “Name” parameter is obviously crucial because after completing the data exchange, if the defined name for a specific element was not properly shown in other user’s software package, some troubles may occur. Secondly, “Geometrical Properties” parameter is also vital, while assessing the geometry and shape of the 3D element. The inaccuracies faced in this stage may lead wrong or inadequate interpretation of the 3D Model. Another parameter investigated is “Material Type” and it gives an idea about the construction duration of the specific element depending on the construction material. So that, it is necessary to obtain the relevant information of “Material Type” for a 4D BIM user after completing IFC exchange. Lastly, “Phase Number” identifies the construction sequence of the specific element. It contains “time” information and this information is the core for 4D BIM users in scheduling, planning and managing of construction activities.

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Although this research includes the discussion of 4D Model transfer, similar approaches can also be performed for higher BIM dimensions. Because the transferred file might also be processed or used for other purposes in another software, it is expected to be more precise and selective in some of the attributes transferred. For example, in 5D BIM dimension, “Name”, “Material Type”, “Geometry” “Quantities” and “Cost” parameters can be considered as the most important ones while performing a 5D analysis.

Additionally, because a rigorous comparison approach was needed for the assessment purposes while analyzing IFC interoperability, some definitions were identified. The main idea of these definitions was to demonstrate differences between interoperability levels observed during the IFC interoperability assessment, in a coherent way. Thus, related definitions used in further parts can be presented beforehand as:

✓: Good Interoperability: The exported parameter was successfully transferred and clearly expressed in BIM software that file was imported.

: Medium Interoperability: The exported parameter was transferred but not clearly expressed or lost some details in BIM software that the IFC file was imported. However, the obtained information can still be used and meaningful for the users.

: Poor Interoperability: The exported parameter was transferred but not as it was in primary BIM tool. The parameter changed and can be misleading.

: No data found: The parameter was not found in the software that the IFC file was imported.

All of these criteria were also re-shown right under each table used for interoperability analysis through IFC standard to make readers more comfortable while observing the results.

Consequently, in the following parts regarding IFC interoperability analysis of the 4D model, the results were explained in terms of interoperability levels of chosen parameters.

In this part of the research, IFC interoperability assessment from Tekla Structures to ACCA Edificius was presented. The performed tests can correspond to a workflow between two different designers, planning engineers, consultant or even a construction manager as both software can be used by these disciplines. In Figure 2-11, relevant test was represented:

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Figure 2-11: IFC Interoperability Analysis from Tekla Structures to ACCA Edificius

As mentioned before, 4D sample model for the test was prepared in Tekla Structures. The exported IFC2x3 file was imported to ACCA Edificius software by using commands: Nuovo>Documento IFC, as it was also presented in Figure 2-12.

Figure 2-12: ACCA Edificius IFC Import Option

After completing IFC file import processing in ACCA Edificius, the general view of the sample model can be seen in Figure 2-13.

Figure 2-13: Front and Back View of the Sample Model in ACCA Edificius

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From the big picture, most of the imported IFC objects (3D information) were translated and clearly defined in ACCA Edificius. Only looking at the front and back views, all the structural elements seem in the proper place as in Figure 2-13. However, for detailed investigation regarding the geometry, presence of the elements and embedded semantic information, it is necessary to dig around and go deeper in 4D model.

More detailed assessment for chosen repetitive elements was tabulated and presented in the below for the IFC interoperability analysis from Tekla Structures to ACCA Edificius Software.

The evaluation was performed by checking all the repetitive elements and corresponding chosen parameters in ACCA Edificius. From Table 2-4 to Table 2-6 the assessment results in which the interoperability conditions described in Section 2.1 employed can be seen:

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Table 2-4: Tekla Structures to ACCA Edificius IFC Interoperability Analysis Result (1)

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Table 2-5: Tekla Structures to ACCA Edificius IFC Interoperability Analysis Result (2)

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Table 2-6: Tekla Structures to ACCA Edificius IFC Interoperability Analysis Result (3)

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After completing the analysis, there are some interesting findings to discuss about interoperability analysis from Tekla Structures to ACCA Edificius. First of all, the ACCA Edificius software identifies the elements in the section of “Descrizione”. It describes the elements by [IfcEntity, ‘Name defined in the Source Software (in this case Tekla Structures) for the Object’, Dimensions]. For example, for “Element 1” the description is given as “IfcSlab ‘SLAB’ (300*2100)” and can be seen from the Figure 2-14 below.

Figure 2-14: Description of Element 1 in ACCA Edificius

In Element 7, there are some missing details in the representation of the object. Although, the longitudinal rebars were perfectly defined, stirrups in the mid-column were not included in the 3D representation. Having this problem can be spotted effortlessly for a structural engineer. Nevertheless, in the side of project management, even if the missing information might not create significant scheduling or planning errors of the tasks, in the side of cost management, it has to be taken into account.

Next discussion is about the material types that was shown by ACCA Edificius. In Edificius, shown material type was not clear. In other words, the material types were named with some numbers which was not giving a direct idea about the structural material. However, the same numbers were given to the similar elements such as all the slabs were defined with “1 – Material 21”. So that, the same numbers indicate the same material type. A sample representation of the first 3 slab elements can be used to express the problem and they were shown in the Figure 2-15 below:

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Figure 2-15: Material Type Display in ACCA Edificius for Selected Slab Elements

Additionally, similar representation was also observed in other elements such as panels, handrails and windows. Consequently, the interoperability of this parameter was not efficient and evaluated as “Poor Interoperability”.

From the project management point of view, the most significant discussion about the Interoperability Analysis from Tekla Structures to ACCA Edificius is that, ACCA Edificius does not provide “Phase” information which was embedded to the IFC Model. This means, if a designer or owner of the project uses Tekla Structures to include the time information inside the Tekla IFC model, it is not possible to transfer the phase information just by using the IFC file. If this way is preferred to be used by different collaborators, there might be a necessity of using another BIM tool to obtain the phase information.

Additionally, in ACCA Edificius, creating Gantt Chart and a construction visualization is possible, however the software does not allow users to export the produced Gantt Chart or

46 | P a g e import another one into the software. In this sense, it is not possible to collaborate with stakeholders by use of Gantt Charts. As a sample representation, a simple produced Gantt Chart for the reference model was given in the Figure 2-16.

Figure 2-16: Gantt Chart Production in ACCA Edificius

Second performed benchmark test was to investigate the interoperability performance from Tekla Structures to Navisworks. This benchmark test was performed to reproduce a workflow between a designer who uses Tekla Structures and a planning engineer, construction manager, project manager or consultant whoever uses Navisworks and identify possible issues which can be faced in practical applications. Navisworks is used to manage construction project tasks, even so, manipulating the design model is a must for scheduling and time- management of construction project tasks. Because the design of a project can be exchanged through IFC standard, so that collaboration between designers and planners can be established firmly. In this chapter, findings were expressed for a case in which the produced IFC2x3 file exported from Tekla Structures and imported to Autodesk Navisworks.

The followed path can be seen in Figure 2-17.

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Figure 2-17: IFC Interoperability Analysis from Tekla Structures to Navisworks

In Navisworks an assessment was performed to analyze spatial and non-graphical information such as name, graphical properties, material type and phase number transferred from Tekla Structures.

The 3D view of the sample model in Navisworks is given in the below Figure 2-18:

Figure 2-18: Front and Back View of the Sample Model in Navisworks

For this study, just like the previous one, some repetitive elements were picked and investigated to see the data-losses or conflicts by checking their properties. The chosen repetitive elements are the same as the first case. The comparison results of chosen repetitive elements from Tekla Structures to Navisworks were given from Table 2-7 to Table 2-9.

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Table 2-7: Tekla Structures to Navisworks IFC Interoperability Analysis Result (1)

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Table 2-8: Tekla Structures to Navisworks IFC Interoperability Analysis Result (2)

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Table 2-9: Tekla Structures to Navisworks IFC Interoperability Analysis Result (3)

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In Element 7, there was a problem related to the “stirrups” of the column element. Although, it was defined and designed in Tekla Structures software, it was not possible to see the stirrups in Autodesk Navisworks. In project management, this may influence planning engineer’s suggestions and solutions related to scheduling slightly. However, this missing representation of stirrups may not have a vital influence on the project also because it can be easily identified by engineers.

In Element 7, 10 and 11 phase numbers embedded in Tekla Structures were not provided in Navisworks. The common points of these elements are all steel material and defined as components in Tekla Structures. The reason of incompatibility can be that, Navisworks data translate mechanism for IFC may not deliver a decent resolution with Tekla Structures.

In Element 14, the representation of the element was not clear as it was in Tekla Structures. The details were given in Tekla Structures was not defined in Navisworks. Although this issue, other information was exchanged properly except “Phase Number”. Again, the possible reason for this can be the incompatibility between Autodesk Navisworks and Tekla Structures.

Consequently, the aim of this assessment was to identify if a 4D model can be transferred from Tekla Structures to Navisworks by use of IFC. Except the issues presented above, in general a simple workflow between stakeholders may be accomplished without too many additional works after IFC file exchange.

Third benchmark test was performed to identify the lack of interoperability from Tekla Structures to Synchro Pro. This test was performed with exported IFC file from Tekla Structures. Afterwards, same IFC file was imported in Synchro Pro.

The followed study methodology from Tekla Structures to Synchro Pro is given in Figure 2-19:

Figure 2-19: IFC Interoperability Analysis from Tekla Structures to Synchro Pro

The front and back views of the sample structure were obtained after importing the IFC file to Synchro Pro was given in this Figure 2-20 below:

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Figure 2-20: Front and Back View of the Sample Model in Synchro Pro

From the first impression of the above Figure 2-20, the conflicts can be seen in reinforcements including stirrups and longitudinal rebars. So that, exchanged IFC file data was not translated and shown accurately in Synchro Pro. However, except this conflict other components looked like complete and well exchanged at first sight.

Though, a detailed spatial and object property investigation is necessary to measure the effectiveness of IFC standard usage from Tekla Structures to Synchro Pro by detecting conflicts if there is any other and evaluate their effects to construction project management. Additionally, the other concern was if 4D Model can be exploited properly in Synchro Pro. Thus, the same type of analysis used before was performed again in this section. The chosen repetitive elements are the same elements which were chosen in the previous sections and conflicts in the IFC model due to the interoperability were presented in the following, from Table 2-10 to Table 2-12:

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Table 2-10: Tekla Structures to Synchro Pro IFC Interoperability Analysis Result (1)

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Table 2-11: Tekla Structures to Synchro Pro IFC Interoperability Analysis Result (2)

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Table 2-12: Tekla Structures to Synchro Pro IFC Interoperability Analysis Result (3)

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The above elements were examined to compare the data-losses or conflicts by checking their geometries and properties. Starting from Element 7, graphical representation of rebar elements is confusing and poor in Synchro Pro for this case. The stirrups and longitudinal rebar elements were not well represented, and manual selection of these elements was a predicament. Additionally, for element 7, phase information was not defined in Synchro Pro just like the previous software packages tested.

Secondly, in Element 11 and Element 14 the related phase numbers were not specified in Synchro Pro, too. Again, their common point is that, they are all defined as “Components” in Tekla Structures.

Lastly, the geometrical representation of Element 14 was not properly shown in Synchro Pro. However, the related information about the material type and other meta-data was properly transferred and readable.

As a result of this IFC Analysis from Tekla Structures to Synchro Pro, 4D Model exchange could be performed with some defects which were identified above. In project management, these defects should be fixed properly and issues regarding representation of steel rebar elements might be solved by some add-in or another software package.

The 4D model was also assessed by use of IFC viewer BIM software usBIM.viewer+. In this case, the exported IFC file was imported to usBIM.viewer+ for 4D Model assessments similarly to previous cases. The relevant workflow of the test was given in Figure 2-21:

Figure 2-21: IFC Interoperability Analysis from Tekla Structures to usBIM.viewer

From the front and back views of the model, the IFC viewer software made a reasonable interpretation in the sense of visualizing the model elements as it can be seen in Figure 2-22 below. For example, usBIM.viewer+ defined welding and bolt details of the sample model properly for the users. Additionally, geometric shapes of the structural objects and openings in the structure were well defined. By default, gridlines for each floor was also displayed. Finally, as an IFC viewer tool, it has adequate capabilities of performing simple tasks in BIM use.

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Figure 2-22: Front and Back View of the Sample Model in usBIM.viewer

For detailed assessment purposes, same objects chosen for previous benchmark tests were also exploited in this part.

The results assessed in this experimentation can be seen from Table 2-13 to Table 2-15:

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Table 2-13: Tekla Structures to usBIM.viewer IFC Interoperability Analysis Result (1)

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Table 2-14: Tekla Structures to usBIM.viewer IFC Interoperability Analysis Result (2)

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Table 2-15: Tekla Structures to usBIM.viewer IFC Interoperability Analysis Result (3)

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After the inspection of the chosen elements there were some issues faced throughout the process. Starting from Element 7, as they were represented in the other software packages some of the stirrups were missing also in usBIM.viewer+. “Name”, “Material Type” and “Phase Number” parameters were all presented correctly in usBIM.viewer+. A special attention must be paid to “Phase Number”, because in the other software packages used in IFC analysis, phase information was not provided before.

Figure 2-23: Phase Number Specified in usBIM.viewer

Likewise, the other BIM tools used before, Element 10 and Element 11 do not have “Phase Number” also in this software.

Regarding the Element 11, the bolts defined were shown with missing representation of the complete bolt connection.

In Element 14, the surface treatment element was not represented as it was shown in Tekla Structures. However, this can be neglected with the meta-data provided for this specific element.

As a result of this analysis, use of usBIM.viewer+ can be supportive with another BIM package to obtain missing information or resolve conflicts.

The other IFC viewer available in the market is Solibri and it is also mostly preferred by stakeholders in AEC industry. Here, the presentation of a workflow from Tekla Structure to Solibri through IFC file was introduced. The workflow can be given as in the Figure 2-24:

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Figure 2-24: IFC Interoperability Analysis from Tekla Structures to Solibri

Figure 2-25: Front and Back View of the Sample Model in Solibri

From the front and back 3D views in Figure 2-25, the structural elements can be identified properly. The openings in the walls, geometrical definitions of the structural elements were clearly displayed. However, a deep investigation should be performed for detection of interoperability issues.

In the following, from Table 2-16 to Table 2-18, results of the IFC assessment was given to express interoperability results from Tekla Structures to Solibri:

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Table 2-16: Tekla Structures to Solibri IFC Interoperability Result (1)

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Table 2-17: Tekla Structures to Solibri IFC Interoperability Result (2)

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Table 2-18: Tekla Structures to Solibri IFC Interoperability Result (3)

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In the previous analysis Element 7 was suffering from lack of stirrup representations. However, this display problem was not occurred in Solibri and they were successfully represented.

In Element 10 and 14 which are defined as IfcCovering and Element 11 which is defined as IfcMechanicalFastener do not include phase numbers.

Lastly, Element 14, surface treatment representation was not clearly defined as in Tekla Structures.

Use of Solibri software can be preferred when the IFC file translation was not adequately performed by the mainly used BIM tool for modification of the model.

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Gantt Chart Interoperability Analysis from Tekla Structures to CPM Software Likewise, the other industries, timing, deadlines and task durations have vital importance also in AEC industry. This argument emphasizes the value of methods to set schedules, create timetables and time management. As mentioned before, Gantt Charts are one of the most used methods. In AEC industry, they are generally produced by Construction Project Management software or BIM software which are capable. More specifically, by combining Gantt Charts with 3D Models, a 4D Model can be obtained and used to visualize and manage construction steps properly. However, in the use of this solid method, there might be some challenges regarding interoperability, because of the possible workflow between stakeholders. Unless each stakeholder uses the same software, the conflicts can be expected in Gantt Chart interoperability from one software to another.

Figure 2-26: Gantt Chart Interoperability Analysis from Tekla Structures to CPM Software

In this part of the research, the interoperability analysis of produced Gantt Charts was presented to identify the possible incompatibilities between BIM software which can occur in exporting/importing Gantt Charts.

Incompatibilities of Gantt Chart interoperability can be defined as investigation of the differences in schedules (i.e. Gantt Charts) from one tool to another.

Considering the real applications, the criteria to study in the assessment of Gantt Chart exchange can be given as:

Is the Gantt Chart exported completely? Is there any data-loss or change? How much the effect of these changes to the project management?

Starting point of this research was to produce a Gantt Chart in Tekla Structures to analyze the Gantt Chart interoperability. In Tekla Structures, the followed way of producing Gantt Chart is given in the Figure 2-27 below:

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Figure 2-27: Tekla Structures Task Manager for Producing Gantt Charts

In Tekla Structures, there are a lot of “Task List Items” to produce Gantt Chart, such that: “Task Name”, “Task Type”, “Planned Start Date”, “Planned Duration”, “Planned End Date”, “Actual Start Date”, “Actual End Date”, “Quantity”, “Contractor”, “Percentage Complete”, “Milestone Task”, etc. However, for this study, necessary fields to add information were: “Task Name”, “Planned Start Date”, “Planned Duration” and “Planned End Date”.

The assigned values for chosen fields: “Task Names” were decided according to the designed elements and “Start”/“End” dates were designated in a generic way. The Gantt Chart produced in Tekla Structures contains assigned various structural elements to main tasks and subtasks according to a logical sequence.

The produced Gantt Chart in Tekla Structures for the assessment was given in the following Figure 2-28:

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Figure 2-28: Gantt Chart Produced In Tekla Structures

After this step, it was necessary to export this produced Gantt Chart for exchange purposes in XML format.

In practical applications, Microsoft Project 2013 is commonly used in AEC industry, especially with combination of BIM software packages to create 4D Models. Thus, it is a decent notion to embody a workflow from Tekla Structures to Microsoft Project 2013.

Firstly, the previously introduced Gantt Chart in Figure 2-28 which was produced in Tekla Structures was exported as XML file format and imported into MS Project 2013.The procedure was given in Figure 2-29, for this experimentation.

Figure 2-29: Gantt Chart Transfer from Tekla Structures to MS Project 2013

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After importing the XML file into Microsoft Project 2013, the obtained Gantt Chart was given in the Figure 2-30 below:

Figure 2-30: Gantt Chart Output of MS Project 2013 After Import Process

Compared Input Interoperability Condition (Tekla Structures➔MS Project 2013) Task Name ✓: Good Interoperability Planned Start Date ✓: Good Interoperability Task Duration ✓: Good Interoperability Planned End Date ✓: Good Interoperability Legend: ✓: Good Interoperability: The input information successfully imported. : Medium Interoperability: The input information imported with small differences, not completely different than initial one. Slight adjustments are necessary. : Poor Interoperability: The input data is completely different or totally lost and meaningless for use. Table 2-19: Gantt Chart Interoperability Analysis Results from Tekla Structures to MS Project 2013

By comparing the Gantt Chart produced in Tekla Structures (Figure 2-28) and MS Project 2013 Gantt Chart (Figure 2-30), it can be surely said that, the interoperability of Gantt Charts from Tekla Structures to MS Project 2013 is successful and satisfying. The relevant results were given in Table 2-19, in detail.

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In this part of the report, it was presented how the time information exchanged from Tekla Structures to MS Project 2016 by use of Gantt Chart. This specific case can be the representation of a workflow between a designer or an owner who uses Tekla Structures and a planning engineer, construction/project manager or a consultant who uses Microsoft Project 2016. The workflow was given in the Figure 2-31 below:

Figure 2-31: Gantt Chart Transfer from Tekla Structures to MS Project 2013

The produced Gantt Charts imported into Microsoft Project 2016 and the output obtained was given in the following Figure 2-32:

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Figure 2-32: Gantt Chart Output of MS Project 2016 After Import Process

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A comparison was performed to see if the input information “Task Name”, “Start Date”, “Task Duration” and “End Date” were changed/lost or not.

The interoperability condition results of Gantt Chart produced in Tekla Structures and the output of the MS Project 2016 can be seen from the Table 2-20 below:

Compared Input Interoperability Condition (Tekla Structures➔MS Project 2016) Task Name ✓: Good Interoperability Planned Start Date ✓: Good Interoperability Task Duration : Medium Interoperability Planned End Date : Medium Interoperability

Legend: ✓: Good Interoperability: The input information successfully imported. : Medium Interoperability: The input information imported with small differences, not completely different than initial one. Slight adjustments are necessary. : Poor Interoperability: The input data is completely different or totally lost and meaningless for use. Table 2-20: Gantt Chart Interoperability Analysis Results from Tekla Structures to MS Project 2016

Consequently, in the analysis results regarding “Task Name” and “Planned Start Date” outputs were correctly exchanged from Tekla Structures to MS Project 2016. However, “Task Duration” and logically “Planned End Date” inputs were not properly transferred. In “Task Duration”, there were slight changes in the assigned values of each task. The reason for this can be the incompatibilities of two software groups while taking into consideration of the Non-Working Days or Working Hours.

As a result, integration of these two software packages can be successfully used if the users make minor adjustments in the outputs.

IFC interoperability analysis of 4D Model from Tekla Structures to Navisworks was discussed before. Considering an alternative way of time information exchange between these two software, Gantt Chart interoperability is also another challenge.

In this part, a Gantt Chart Interoperability Analysis from Tekla Structures to Navisworks was performed in two different ways to identify the possible issues faced throughout the workflow.

In Navisworks, there are various ways of importing data and each method can be seen from the Figure 2-33:

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Figure 2-33: Data Import Methods in Navisworks

The possibility of importing different file types into Navisworks allows performing different analyses. In this study, use of Primavera P6 Software and MS Project MPX format (It was supported up to MS Project 2010 [47]) was excluded.

Gantt Chart Interoperability Analysis from Tekla Structures to Navisworks was performed in two different methods to identify the possible issues faced throughout all the workflows.

a) Method 1: Analysis via MS Project 2013 Option

First method was the way of importing the XML file by use of MS Project 2007-2013 option. To be able to use this option, stakeholders must have one of these versions of MS Project, otherwise having only exported XML file from Tekla Structures is not enough to perform data import. The reason is that, Navisworks uses MS Project 2007-2013 as a source software. The relevant workflow was given in the following Figure 2-34:

Figure 2-34: Gantt Chart Transfer from Tekla Structures to Navisworks by Using MS Project 2013

Firstly, the Gantt Chart produced in Tekla Structures was exported in XML format. The XML format was imported as “Data Source” into Navisworks, as in Figure 2-35:

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Figure 2-35: Data Source Adding in Navisworks

After completing import operation, applying “Rebuild Task Hierarchy” command in Navisworks, the Gantt Chart obtained and presented in Figure 2-36 below:

Figure 2-36: Gantt Chart Output of MS Navisworks After Import Process via MS Project 2013

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Compared Input Interoperability Condition (Tekla Structures➔Navisworks via MS Project 2013) Task Name ✓: Good Interoperability Planned Start Date ✓: Good Interoperability Task Duration No field provided in Navisworks Planned End Date ✓: Good Interoperability Legend: ✓: Good Interoperability: The input information successfully imported. : Medium Interoperability: The input information imported with small differences, not completely different than initial one. Slight adjustments are necessary. : Poor Interoperability: The input data is completely different or totally lost and meaningless for use. Table 2-21: Gantt Chart Interoperability Analysis Results from Tekla Structures to Navisworks via MS Project 2013

The imported Gantt Chart was compared with the one produced in Tekla Structures in above table. As it can be seen from both Gantt Charts, the output of Navisworks is clearly defined and every detail is visible except “Task Duration” because of the way Navisworks operates.

In the sense of Construction Project Management, the workflow of sharing Gantt Charts from Tekla Structures to Navisworks by the help of MS Project 2013 proceeds flawlessly according to the performed experimentation.

b) Method 2: Analysis by use of CSV Import via MS Project 2016

The second approach discussed in this section includes use of CSV import. For this purpose, conversion from XML to CSV file format was needed by Microsoft Project 2016. This option can be useful when stakeholders do not have older versions of Microsoft Project 2016. The Gantt Chart XML file produced in Tekla Structures (Figure 2-28) was previously imported into Microsoft Project 2016 and Gantt Chart output was also presented in Figure 2-32. The results regarding this experimentation was also presented in “Section 2.2.2”, Table 2-20. Even though the results found in that stage was not perfect, Gantt Chart analysis by use of CSV import via MS Project 2016 to Navisworks was performed to identify the changes and lost data in the Gantt Chart.

Afterwards, the XML file shown in Figure 2-32 was saved as CSV file by Microsoft Project 2016. Lastly, this obtained CSV file was imported into Navisworks using the command specified as “CSV Import” in Figure 2-33. The workflow can be seen from the Figure 2-37 below for better understanding of the concept:

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Figure 2-37: Gantt Chart Transfer from Tekla Structures to Navisworks by Using MS Project 2016 in CSV Format

Figure 2-38: CSV Import in Navisworks

After performing CSV import and using “Rebuild Task Hierarchy” command the added data would be seen in Tasks tab. In the Figure 2-39, the Gantt Chart output of Navisworks can be seen:

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Figure 2-39: Gantt Chart Output of MS Navisworks After CSV Import Process via MS Project 2016

Keeping in the mind the conflicts regarding the Gantt Chart analysis from Tekla Structures to Microsoft Project 2016, there were mismatching task durations and task end dates. The comparison results of the Gantt Chart in Figure 2-39 with Microsoft Project 2016 Gantt Chart output in Figure 2-32 and produced Gantt Chart in Tekla Structures in Figure 2-28 were presented below in Table 2-22:

Compared Input Interoperability Condition (Tekla Structures➔Autodesk Navisworks in CSV format) Task Name ✓: Good Interoperability Planned Start Date ✓: Good Interoperability Task Duration No field provided in Navisworks Planned End Date : Medium Interoperability Legend: ✓: Good Interoperability: The input information successfully imported. : Medium Interoperability: The input information imported with small differences, not completely different than initial one. Slight adjustments are necessary. : Poor Interoperability: The input data is completely different or totally lost and meaningless for use. Table 2-22: Gantt Chart Interoperability Analysis Results from Tekla Structures to Navisworks by CSV format

It is obvious that, the “Task Name” and “Planned Start Date” exchange were successfully achieved from Tekla Structures to Navisworks by use of CVS for each task in Gantt Chart. However, there were some problems regarding the “Planned End Date” of each task. Additionally, in Navisworks there is no field separated for “Task Duration” value input.

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The interoperability of the Gantt Chart file created (Figure 2-28) in Tekla Structures was also examined in Synchro Pro. This XML file was exported from Tekla Structures and imported into Synchro Pro. The procedure can be seen from the Figure 2-40.

Figure 2-40: Gantt Chart Transfer from Tekla Structures to Synchro Pro

In Synchro Pro, the imported Gantt Chart was obtained as Figure 2-41 and interoperability analysis results were tabulated in Table 2-23:

Figure 2-41: Gantt Chart Output of Synchro Pro After Importing From Tekla Structures

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Compared Input Interoperability Condition (Tekla Structures➔Synchro Pro) Task Name ✓: Good Interoperability Planned Start Date ✓: Good Interoperability Task Duration ✓: Good Interoperability Planned End Date ✓: Good Interoperability Legend: ✓: Good Interoperability: The input information successfully imported. : Medium Interoperability: The input information imported with small differences, not completely different than initial one. Slight adjustments are necessary. : Poor Interoperability: The input data is completely different or totally lost and meaningless for use. Table 2-23: Gantt Chart Interoperability Analysis Results from Tekla Structures to Synchro Pro

The result of this interoperability analysis was very satisfactory because if one checks the “Task Name”, “Subtask Name”, “Start Date”, “End Date” and “Task Duration” in Synchro PRO output of the imported Tekla Structures Gantt Chart, it is clearly visible that all mentioned parameters are correctly exchanged and presented. This part of the research shows that, in practical cases, use of Tekla Structures and Synchro Pro together can reduce the errors due to the interoperability problems and saves time. So that, it increases efficiency of communication between stakeholders. As a result, a strong collaboration can be achieved by use of this procedure.

Consequently, the main result that can be reached is that, the export and import mechanism of XML files in both software packages are the same. From Tekla Structures to Synchro Pro, the Gantt Chart import is supported well.

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Gantt Chart Interoperability Analysis from CPM Software to Tekla Structures In practice, a planning engineer, construction manager or a consultant can share the schedules with designers or project owners. This aspect of information sharing is significant like the ones in Section 2.2., in the sense of supporting collaboration of stakeholders. This direction of workflow between stakeholders require an additional interoperability analysis regarding time information. Because in this thesis study, Tekla Structures was the main design software considered, the imitated workflows were started from a CPM software and end up in Tekla Structures. The produced Gantt Charts in each CPM software was exported and then, imported into Tekla Structures to measure the efficiency of the interoperability. The procedure for this task can be seen in Figure 2-42 below:

Figure 2-42: Gantt Chart Interoperability Analysis from CPM Software to Tekla Structures

In this part, the analysis was explored from MS Project 2013 to Tekla Structures. This way of utilizing MS Project 2013 is frequently applied with BIM software tools. In this case, a planning engineer or a project construction can import a schedule by Gantt Chart from Microsoft Project 2013 to Tekla Structures. The procedure for this experimentation was given in Figure 2-43:

Figure 2-43: Gantt Chart Transfer from MS Project 2013 to Tekla Structures

A simple Gantt Chart was produced in MS Project 2013 to perform the analysis. The related Gantt Chart was given in the following Figure 2-44:

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Figure 2-44: Gantt Chart Produced in MS Project 2013

This Gantt Chart was imported into Tekla Structures for analysis purposes. Thus, obtained Gantt Chart output in Tekla Structures was given in the following Figure 2-45:

Figure 2-45: Gantt Chart Output of Tekla Structures After Importing From MS Project 2013.

As it can be seen from the Figure 2-45, for this simple created Gantt Chart in MS Project 2013, the XML file type exchange was performed with a very small error in the 3rd task which is named as “Second Floor”. The planned duration for this task was not read properly by Tekla Structures. However, because the Task End Dates were correctly transferred, this problem can be fixed with small adjustments. The detailed investigation results were represented in Table 2-24 below.

An important note should be added here to point out that, although, the produced Gantt Chart for this case has not too many details and not complicated, this negligible problem was identified. For complicated Gantt Charts produced in MS Project 2013, there might be some other issues throughout the procedure.

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Compared Input Interoperability Condition (MS Project 2013➔Tekla Structure) Task Name ✓: Good Interoperability Planned Start Date ✓: Good Interoperability Task Duration : Medium Interoperability Planned End Date ✓: Good Interoperability

Legend: ✓: Good Interoperability: The input information successfully imported. : Medium Interoperability: The input information imported with small differences, not completely different than initial one. Slight adjustments are necessary. : Poor Interoperability: The input data is completely different or totally lost and meaningless for use. Table 2-24: Gantt Chart Interoperability Analysis Results from MS Project 2013 to Tekla Structures

In this part of the research a reverse analysis was performed to see how the XML data was processed from MS Project 2016 to Tekla Structures. In Figure 2-46, the representation of the procedure was given:

Figure 2-46: Gantt Chart Transfer from MS Project 2016 to Tekla Structures

The primary work was to create a very simple Gantt Chart in MS Project by defining “Duration”, “Start Date” and obviously “End Date”.

In the following Figure 2-47, one can find the related documentation of Gantt Chart which was produced in MS Project.

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Figure 2-47: Gantt Chart Produced in MS Project 2016

For the assessment, it was required to perform interoperability analysis from MS Project 2016 to Tekla Structures. The above Gantt Chart was saved in XML format in MS Project 2016 software and imported into Tekla Structures.

In the following Figure 2-48, the result regarding the XML output of the above created Gantt Chart in Tekla Structures was given. According to the results obtained, it was proved that an XML file which was produced and saved in MS Project can be used without loss of data in Tekla Structures. So that, one can say that exchanging files from MS Project 2016 to Tekla Structures are effectively performed.

Figure 2-48: Gantt Chart Output of Tekla Structure After Importing from MS Project 2016

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Compared Input Interoperability Condition (MS Project 2016➔Tekla Structures) Task Name ✓: Good Interoperability Planned Start Date ✓: Good Interoperability Task Duration ✓: Good Interoperability Planned End Date ✓: Good Interoperability

Legend: ✓: Good Interoperability: The input information successfully imported. : Medium Interoperability: The input information imported with small differences, not completely different than initial one. Slight adjustments are necessary. : Poor Interoperability: The input data is completely different or totally lost and meaningless for use. Table 2-25: Gantt Chart Interoperability Analysis Results from MS Project 2016 to Tekla Structures

The conclusion of this assessment was given in Table 2-25. As one can see results of Tekla Structures output for this simple case, the interoperability operations from MS Project 2016 to Tekla Structures might be accepted as applicable in real-life projects.

In practice, throughout a workflow Gantt Chart exchange from Navisworks to Tekla Structures is also possible between various stakeholders. For example, a Gantt Chart which is produced in Navisworks can be imported to Tekla Structures with the purpose of reviewing, controlling or managing assigned tasks. So that, Gantt Chart Interoperability Analysis from Navisworks to Tekla Structures was also performed.

Because the result shared in “Section 2.2.3 - Method 1” for Gantt Chart interoperability analysis from Tekla Structures to Navisworks was satisfying, the same Gantt Chart was used for the reverse-way analysis. In this analysis the Gantt Chart in Figure 2-36 was exported from Navisworks and imported into Tekla Structures in XML format. The procedure for this task was given in Figure 2-49.

Figure 2-49: Gantt Chart Transfer from MS Project 2016 to Tekla Structures

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The important point to mention here is that, while exporting the XML file which consists of Gantt Chart in Figure 2-36, Navisworks warning was appeared, and it can be seen from the Figure 2-50 below:

Figure 2-50: Warning Appeared in Navisworks Regarding Round-Tripping.

The term “Round-Tripping” stated here refers to the interoperability procedure which started from Tekla Structures and proceeded in Navisworks and then eventually, ended up in Tekla Structures. Even though, “Round-Tripping” is not recommended by Autodesk Navisworks, the research was continued to find out the possible outcomes.

After import operation of XML file produced in Navisworks into Tekla Structures, the Gantt Chart output can be seen from the Figure 2-51:

Figure 2-51: Gantt Chart Output of Tekla Structure After Importing from Navisworks by Round-Tripping

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The results obtained from the comparison of these two Gantt Charts can be seen from the Table 2-26 below:

Compared Input Interoperability Condition (Autodesk Navisworks➔Tekla Structures by “Round-Tripping”) Task Name ✓: Good Interoperability Planned Start Date ✓: Good Interoperability Task Duration : Poor Interoperability Planned End Date : Poor Interoperability

Legend: ✓: Good Interoperability: The input information successfully imported. : Medium Interoperability: The input information imported with small differences, not completely different than initial one. Slight adjustments are necessary. : Poor Interoperability: The input data is completely different or totally lost and meaningless for use. Table 2-26: Gantt Chart Interoperability Analysis Results from Navisworks to Tekla Structures by Round-Tripping

From the comparison of the Gantt Charts in Figure 2-36 and Figure 2-51, there are some points to notice such as, task names and planned start dates are the same with the ones in Navisworks. However, the noteworthy point is that, planned duration for each task was not well defined and irrelevant than the ones defined in Navisworks Gantt Chart. Obviously, depending on the “Task Duration” inputs, “Planned End Date” outputs were also not correctly translated. The reason for this issue can be shown as, lack of “Task Duration” in Navisworks can lead this type of incompatibilities between BIM software.

Because of the warning related to “Round-Tripping”, it was necessary to understand if the source of error was due to the “Round-Tripping” or incompatibility between these two software packages. So that, an additional investigation was performed to understand the reason of ineffective XML exchange from Navisworks to Tekla. A simple Gantt chart was prepared and exported as XML from Navisworks and it can be seen from the Figure 2-52.

Figure 2-52: Gantt Chart Produced In Navisworks

Then, produced Gantt Chart imported into Tekla Structures. The output obtained in Tekla Structures after this operation was given in Figure 2-53:

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Figure 2-53: Gantt Chart Output of Tekla Structure After Importing from Navisworks

As it can be seen from the visual comparison of Figure 2-52 and Figure 2-53 Gantt Charts, the problems related to “Task Duration” and “Planned End Date” were continuing. As these two inputs were lost in Figure 2-51, similar results were obtained also in Figure 2-53. The analysis result can be seen below in Table 2-27:

Compared Input (Autodesk Navisworks➔Tekla Structures by Simple Interoperability Condition Gantt Chart produced in Navisworks) Task Name ✓: Good Interoperability Planned Start Date ✓: Good Interoperability Task Duration : Poor Interoperability Planned End Date : Poor Interoperability

Legend: ✓: Good Interoperability: The input information successfully imported. : Medium Interoperability: The input information imported with small differences, not completely different than initial one. Slight adjustments are necessary. : Poor Interoperability: The input data is completely different or totally lost and meaningless for use. Table 2-27: Gantt Chart Interoperability Analysis Results from Navisworks to Tekla Structures

Considering the two cases, as a result, the problem in Gantt Chart interoperability was due to the incompatibility between Navisworks and Tekla Structures.

In this section, a reverse-way of the experimentation introduced in “Section 2.2.4” was presented. Here, the XML file export was performed to assess the interoperability operation from Synchro Pro to Tekla Structures. For this task, because the Gantt Chart transfer from Tekla Structures to Synchro Pro was successful, the output obtained in Synchro Pro was used and it was given in Figure 2-41.

Related workflow can be seen from the Figure 2-54:

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Figure 2-54: Gantt Chart Transfer from Synchro Pro to Tekla Structures

The Gantt Chart presented in Figure 2-41 was exported. Afterwards, the concerned file was imported into Tekla Structures to perform an interoperability test on the related Gantt Chart. Keeping in mind that, the consequence of the previously performed Gantt Chart interoperability test in “Section 2.2.4” had a satisfactory result, before doing this experimentation, it was already expected to obtain similar outcomes by appreciating the similarity between XML export/import translators of both software.

Moreover, after importing the XML file, which was exported from Synchro Pro into Tekla Structures, the obtained Gantt Chart was given in the Figure 2-55 below:

Figure 2-55: Gantt Chart Output of Tekla Structure After Importing from Synchro Pro

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Compared Input Interoperability Condition (Synchro Pro➔Tekla Structures) Task Name ✓: Good Interoperability Planned Start Date ✓: Good Interoperability Task Duration ✓: Good Interoperability Planned End Date ✓: Good Interoperability Legend: ✓: Good Interoperability: The input information successfully imported. : Medium Interoperability: The input information imported with small differences, not completely different than initial one. Slight adjustments are necessary. : Poor Interoperability: The input data is completely different or totally lost and meaningless for use. Table 2-28: Gantt Chart Interoperability Analysis Results from Synchro Pro to Tekla Structures

The obtained result of this interoperability analysis according to the compared inputs was given in Table 2-28. All in all, the result was substantial for the practical use without any flaw or change in the data including the “Task Name”, “Subtask Name”, “Start Date”, “End Date” and “Task Duration”.

It can be surely said that Gantt Chart exchange between Synchro Pro and Tekla Structures was performed without any data loss and provided comfort of utilization for the users without any data modification or manual data entry.

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Gantt Chart Interoperability Analysis Between CPM Software In practical applications, another common way of collaboration between stakeholders is performed by CPM software use. More specifically, produced information in one CPM software must be used in another CPM software package. Even though, MS Project packages are mostly combined with BIM software, this part of the study was dedicated for assessing only the 4D BIM software packages and excluded Microsoft 2013 and Microsoft 2016 for facilitation. Thus, Gantt Chart interoperability analyses can be found in below sections regarding Navisworks and Synchro Pro.

In this specific case, a workflow might be the representative of a collaboration between two different planning engineers or a planning engineer and a construction project manager who use Navisworks in one side and Synchro Pro in other side. Herein, this experimentation discusses the interoperability analysis Gantt Chart produced in Navisworks and imported into Synchro Pro. In the following Figure 2-56 related workflow can be seen:

Figure 2-56: Gantt Chart Transfer from Navisworks to Synchro Pro

For the experimentation, a simple Gantt Chart was produced in Navisworks and it can be seen from the Figure 2-57:

Figure 2-57: Gantt Chart Produced in Navisworks

Afterwards, the created simple Gantt Chart was imported into Synchro Pro and the output of the Synchro Pro was given in the following Figure 2-58:

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Figure 2-58: Gantt Chart Output of Tekla Structure After Importing from Navisworks

As a result, from Navisworks to Synchro Pro, durations for each task could not be obtained. They were defined as “1 day” duration in Synchro Pro. Thus, it has to be pointed out that time duration for different tasks were lost during in this research. Obviously, the date related to “End Date” was also lost. In the sense of lost data, this experimentation is very similar to the Gantt Chart Interoperability Analysis from Navisworks to Tekla Structures.

In other words, the comparison between these two experimentations proves that XML translator mechanisms of Synchro Pro and Tekla Structures are similar and they both have incompatibility with Gantt Charts produced in Navisworks.

Compared Input Interoperability Condition (Navisworks➔Synchro Pro) Task Name ✓: Good Interoperability Planned Start Date ✓: Good Interoperability Task Duration : Poor Interoperability Planned End Date : Poor Interoperability Legend:

✓: Good Interoperability: The input information successfully imported. : Medium Interoperability: The input information imported with small differences, not completely different than initial one. Slight adjustments are necessary. : Poor Interoperability: The input data is completely different or totally lost and meaningless for use. Table 2-29: Gantt Chart Interoperability Analysis Results from Navisworks to Synchro Pro

In the Table 2-29 above, the “Task Duration” and certainly the “Planned End Date” were evaluated as poor interoperable parameters. Because in Navisworks there is no specific cell defined to enter value for assigning the “Task Duration”, information regarding this parameter may not be transferred properly.

The remarkable results obtained in the “Section 2.4.1”, established an interest in the reverse- way Gantt Chart interoperability analysis which means from Synchro Pro to Navisworks. Thus, another implementation was performed by reversing the direction of the workflow presented in

93 | P a g e previous section. In this part, the discussion of a produced simple Gantt Chart in Synchro Pro was imported into Navisworks. In Figure 2-59 the workflow was given:

Figure 2-59: Gantt Chart Transfer from Navisworks to Synchro Pro

Figure 2-60: Gantt Chart Produced in Synchro Pro

Gantt Chart represented in Figure 2-60 was the one produced in Synchro Pro. After exporting this Gantt Chart from Synchro Pro, it was imported into Navisworks by use of “MS Project 2007-2013” option (Figure 2-33) as “Data Source”.

The Navisworks output of the Gantt Chart was given in below Figure 2-61:

Figure 2-61: Gantt Chart Output of Navisworks After Importing from Synchro Pro

After assessing the defined parameters, the results can be seen in Table 2-30:

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Compared Input Interoperability Condition (Synchro Pro➔Navisworks) Task Name ✓: Good Interoperability Planned Start Date ✓: Good Interoperability Task Duration No field provided in Navisworks Planned End Date ✓: Good Interoperability

Legend: ✓: Good Interoperability: The input information successfully imported. : Medium Interoperability: The input information imported with small differences, not completely different than initial one. Slight adjustments are necessary. : Poor Interoperability: The input data is completely different or totally lost and meaningless for use. Table 2-30: Gantt Chart Interoperability Analysis Results from Synchro Pro to Navisworks

As it can be effortlessly approved that exchange of “Task Name”, “Planned Start Date” and “Planned End Date” information was successful. However, because the task durations cannot be specified explicitly in Navisworks, the data related to this information was not presented specifically. Although the fact is this, “Planned Start Date” and “Planned End Date” parameters were correctly displayed. In practice, lack of “Task Duration” representation may lead some other major problems such as neglecting “non-working days” or any other confusions related to work schedule.

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3. CONCLUSION

In this thesis study, the interoperability results regarding 4D BIM Model and Gantt Chart Interoperability Analysis were scrutinized in a diligent way. The produced 4D Model and Gantt Charts were exchanged among various software packages. The experimentations were performed with the commonest software used in AEC industry. The obtained results were assessed according to their attainments of transferring “time” information, schematic data and meta-data embedded to the elements in the sample model.

Obviously, the used software tools have different capabilities, strong features and weak sides. Taking into account their characteristics, to illuminate how they were manipulated according to the experimentation type, the Figure 3-1 was given in the following:

Figure 3-1: Software Packages Used In Interoperability Analyses

The left-hand side software packages ACCA Edificius, usBIM.viewer+ and Solibri were only used for IFC interoperability analysis. The right-hand side group was composed of MS Project 2013 and 2016. These tools were utilized for Gantt Chart Interoperability Analysis. The software tools in the intersection set were used for both experimentations.

Initial point of this thesis study was to investigate the hypothesis of “Impeccable Interoperability between BIM Platforms” while exchanging information by use of IFC Standard and produced Gantt Charts (in XML and CSV formats.)

There were 15 experimentations presented in the previous parts of this study and they can be summarized as:

5 experimentations were performed for IFC Interoperability Analysis,

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4 experimentations were performed for Gantt Chart Interoperability Analysis from Tekla Structures to CPM Software, 4 experimentations were performed for Gantt Chart Interoperability Analysis from CPM Software to Tekla Structures, 2 experimentations were performed for Gantt Chart Interoperability Analysis between CPM Software (Navisworks and Synchro Pro).

In Table 3-1, a comprehensive summary of IFC Interoperability Analysis Results was given with respect to the chosen entities which are mostly important for the construction project management tasks.

IFC Analysis Element Material Phase Result Geometry Name Type Number Experimentation Good Adequate Inadequate Tekla Structures ➔ ACCA Edificius No Transfer Compatibility Compatibility Compatibility Good Adequate Good Adequate Tekla Structures ➔ Navisworks Compatibility Compatibility Compatibility Compatibility Good Inadequate Good Adequate Tekla Structures ➔ Synchro Pro Compatibility Compatibility Compatibility Compatibility Good Adequate Good Adequate Tekla Structures ➔ usBIM.viewer+ Compatibility Compatibility Compatibility Compatibility Good Adequate Good Adequate Tekla Structures ➔ Solibri Compatibility Compatibility Compatibility Compatibility

Legend: Good Compatibility: The entity was transferred successfully without any loss of data. Adequate Compatibility: The entity was transferred with negligible data loss. Inadequate Compatibility: The entity was transferred with some conflicts and substantial data loss. No Transfer: The entity was not transferred.

Table 3-1: IFC Interoperability Analysis Results Summary

In the Table 3-2, the overview of the Gantt Chart Analysis Results was represented in a complete way.

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Gantt Ch. Analysis Res. Task Task Name Start Date End Date Experimentation Duration

Good Good Good Good Tekla Structures ➔ MS Project 2013 Interoperability Interoperability Interoperability Interoperability Good Good Medium Medium Tekla Structures ➔ MS Project 2016 Interoperability Interoperability Interoperability Interoperability Tekla Structures ➔ Navisworks Good Good No data field in Good (Method 1) Interoperability Interoperability Navisworks Interoperability Tekla Structures ➔ Navisworks Good Good No data field in Medium (Method 2) Interoperability Interoperability Navisworks Interoperability Good Good Good Good Tekla Structures ➔ Synchro Pro Interoperability Interoperability Interoperability Interoperability Good Good Medium Good MS Project 2013 ➔ Tekla Structures Interoperability Interoperability Interoperability Interoperability Good Good Good Good MS Project 2016➔ Tekla Structures Interoperability Interoperability Interoperability Interoperability Good Good Poor Poor Navisworks ➔ Tekla Structures Interoperability Interoperability Interoperability Interoperability Good Good Good Good Synchro Pro ➔ Tekla Structures Interoperability Interoperability Interoperability Interoperability Good Good Poor Poor Navisworks ➔ Synchro Pro Interoperability Interoperability Interoperability Interoperability Good Good No data field in Good Synchro Pro ➔ Navisworks Interoperability Interoperability Navisworks Interoperability

Legend: Good Interoperability: The input information successfully imported. Medium Interoperability: The input information imported with small differences, not completely different than initial one. Slight adjustments are necessary. Poor Interoperability: The input data is completely different or totally lost and meaningless for use.

Table 3-2: Gantt Chart Interoperability Analysis Summary

It was observed that, the proficiency of interoperability operations depends on how the export/import translator functions work between BIM tools, internal configuration of neutral file formats and range of data object types exchanged. As the translators of both software tools work coherently, the exchange was more effective. Moreover, having a secure and verified internal configuration neutral file format like the one in IFC, also another important point for quality of interoperability. Lastly, as the range of data types exchanged are less, it is expected to have less problems with interoperability.

As a conclusion, the interoperability problems are triggering issues between stakeholders while performing the most significant tasks in AEC industry. Even though, in this research only the

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“4D Model and Gantt Chart Interoperability Analyses” were touched, there are also other challenges related to the interoperability between structural analysis software and BIM software or cost analysis tools and BIM packages. The known fact is that, these problems cause loss of money, time and workhours for stakeholders who are involved in design, planning and construction phases. Moreover, to resolve these troubles, most of the time the solution is manual data-entry or debugging. However, this can be overwhelming and suffocating for people work in AEC industry and cause reduction in productivity of the stakeholders.

The rational and fruitful approaches of dealing with difficulties in AEC industry regarding interoperability can be suggested as:

Utilization of specialized software add-ins which might be inserted into main software to debug the possible conflicts after importing the IFC file or Gantt Chart collaboratively, Use of software tools from the same software vendor for each stakeholder, if possible, Developments and researches in neutral-file format and standardization can be encouraged more by international institutions, Identifying and exploiting software tools which can work collaboratively and coherently without losing any information, For 4D BIM Model and Gantt Chart utilization, a mobile application which supports IFC and XML file formats can also be developed to deliver the missing information by a virtual environment rather than paper-based documents.

To sum up all the discussions and ideas shared above, it was proven that, although there are initiatives, standardizations and researches in interoperability between BIM tools, there is still much to do and improve.

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