Master’s thesis STRUCTURALCOMPONENTS 4 Conceptual building models with structural design justification Arie Bovenberg Delft University of Technology Faculty of Civil Engineering and Geosciences Department of Structural Engineering Section Structural and Building Engineering This page has been intentionally left blank. Preface This report is the result of the Master’s thesis project of Arie Bovenberg, the fourth in a series of graduation projects on the subject of StructuralComponents: an early stage design tool for structural design (Rolvink et al., 2009). The subject of this thesis is the development of a conceptual building model to support composition of structural design justification. This research is part of a collaboration of the faculty of Civil Engineering and Geo- sciences of the Delft University of Technology, the BEMNext Laboratory, and White Lioness technologies. The graduation committee consisted of the following mem- bers: Prof. dr. ir. J.G. Rots [email protected] Delft University of Technology Faculty of Civil Engineering and Geosciences Structural Mechanics Dr. ir. J.L. Coenders [email protected] Delft University of Technology Faculty of Civil Engineering and Geosciences Structural and Building Engineering White Lioness technologies Ir. A. Rolvink [email protected] Delft University of Technology Faculty of Civil Engineering and Geosciences Structural Mechanics White Lioness technologies Ir. J.W. Welleman [email protected] Delft University of Technology Faculty of Civil Engineering and Geosciences Structural Mechanics Ir. S. Hofman [email protected] Arup Amsterdam iii This page has been intentionally left blank. Summary The adoption of computation in the building industry has led to the development of a range of tools intended for design, but these are often focused on detailed analysis and documentation, instead of flexibility and insight. This results in missed opportunities for computational analysis in the early design stages where decisions are most influential. Also, a large part of the process and reasoning behind these decisions is lost due to a lack of suitable early-stage models. StructuralComponents is a design tool for conceptual structural design which aims to address the needs of the early design stages. The current implementation is focused on quick, insightful analysis of high-rise structures. The main aim of Struc- turalComponents 4 is not only to cover more general structural typologies, but also to model a more complete representation of structural design concepts: not as a single model or analysis method but as a design story or justification, consisting of the various models, simplifications, reasoning, alternatives, and scenarios used to develop and justify the design. The StructuralComponents 4 prototype implementation consists of the conceptual building model, a user interface and a simple computational (parametric) engine. High-level requirements for the tool have been developed based on existing research and insights into (structural) design and conceptual modeling. The iterative devel- opment process of the tool itself has also provided feedback to refine these assump- tions. High-level characteristics of (structural) design indicate the tool must support: • a unique process structure straction and scale • multidimensional problems and in- • various analysis models tegrated solutions • cases and scenarios • parallel alternatives • progression from preliminary to • modeling at different levels of ab- detailed design The resulting central concepts of the conceptual building model are: “Blank slate” components The main building-blocks of the model are components which aim to follow the designers needs, instead of providing a detailed standard. Components can be defined by the user to represent any structural feature, and can contain quantitative as well as qualitative information. Hierarchical component breakdown Components are organized hierarchically to indicate the breakdown of the v structure. This makes it possible to model the structure at several levels of abstraction. Reflective design reasoning Justification behind an design information can be expressed as the result of a design-step, which in turn is based on the context of existing information. This allows a chain of decisions giving insight into the reasoning behind values as well as the effect of changes. Analysis models as automated reasoning Analysis models are implemented as automated logic to be applied in the design-steps, allowing these to be re-run when parameters change. Alternative values The building model supports multiple values per component attribute, allow- ing the user to represent alternative values in parallel. Component variants Complex alternatives are supported through component variants, which com- bine a set of choices for alternative values. These concepts been implemented in the prototype, and have been validated through application in practical cases (see Figure1 for a condensed example). Figure 1: Schematic diagram showing the analysis of the stability of a “core” component in a building model, making use of various analysis models and scenarios. Based on the structural design of the RAI Elicium building (Arup Amsterdam, 2009). The validation shows that the central concepts of the building model sufficiently address the high-level requirements. Notable limitations are the absence of geomet- ric and visual representations, constraints on variation between alternative compo- nents, and lack of overview at detail level. Based on the observations during validation, further directions for investigation are suggested. These include opportunities for standardization; reflection and visual representations; bi-directional associations; geometric associations; replication; dis- tinguishing alternatives and scenarios; and an improved user interface. By making a larger part of the design story explicit, the StructuralComponents 4 building model represents a significant step towards broader application of compu- tation in design, specifically improved communication of reasoning behind design, and more effective use of optimization and analysis trough scenarios and parallel alternatives. This page has been intentionally left blank. Contents Preface iii Summaryv 1 Introduction1 1.1 Background................................1 1.2 StructuralComponents..........................3 1.3 Motivation.................................4 1.4 Objectives.................................5 1.5 Thesis outline...............................7 2 Methodology9 2.1 Approach.................................9 2.2 Research.................................. 11 2.3 Development............................... 11 2.4 Validation................................. 11 3 Research 13 3.1 Design................................... 13 3.2 Modeling................................. 15 3.3 Computation............................... 17 3.4 Conclusion (use cases).......................... 18 4 Results 23 4.1 Application architecture......................... 23 4.2 Conceptual building model....................... 25 4.3 Computational engine.......................... 40 4.4 User interface............................... 44 5 Validation 49 5.1 Examples................................. 49 5.2 Evaluation................................. 61 6 Discussion 65 6.1 Objectives................................. 65 6.2 Background................................ 66 6.3 Next steps................................. 67 6.4 Potential.................................. 71 ix 7 Conclusions 73 References 75 List of Figures 79 Appendices 80 A Case study 81 A.1 Background................................ 81 A.2 Structural design............................. 82 B Development process 87 B.1 Version 0.1................................ 87 B.2 Version 0.2................................ 88 B.3 Version 0.3................................ 89 C Publication 91 1 Introduction This chapter introduces the background and starting points of this study. The first section outlines relevant aspects of structural design, followed by a brief description of StructuralComponents: its approach and previous implementations. Section 1.3 describes the main motivations for this thesis, leading to the objectives outlined in Section 1.4. A description of the thesis structure is given in the last section. 1.1 Background StructuralComponents is a software-tool for the early stages of structural design. It addresses the need for flexible, insight giving tools to suit the complex and dynamic nature of conceptual design. 1.1.1 The design process The process of designing a structure is a complex process, with no predetermined ‘optimal’ result (Chapman et al., 2001). Especially in the early design stages so- lutions are developed by exploring options, with experience and creativity of the designer playing a large role. Figure 1.1 shows two trends throughout the design process. The first is accuracy of information: at the start of design, there is little precise knowledge about the design problem. As the design progresses, accuracy of information increases as the designer gains insight into the problem and develops his or her design. The oppo- site trend occurs for impact of decisions: at the start of the design process all options are open and high-level decisions are made. Later in the process, when the design has been developed, it is often costly to make changes. The effect of this trend is that engineers often have to make influential decisions when information needed to make these decisions is lacking. 1.1.2