n the last two decades, the number of dis- of these your software product supports, as they are crete structural software products we use not necessarily always interoperable. has increased dramatically, along with their CIS/2’s weakness is primarily its lack of robust capabilities, complexity and power. But the support for non-steel materials, lack of an organiza- abilityI of these products to interoperate has not tion or process to continue its development, and its InSights always kept pace. flexibility in implementation (more on this later). “In spite of the great progress of the last decade, new trends, new techniques many obstacles must still be overcome. … Industry Foundation Classes – IFC and current industry issues We now have to zero in on the key issue, Industry Foundation Classes are data models that the Achilles heel of (structural) computer are developed under the auspices of the building programs…Compatibility!” SMART Organization. IFCs have the ambitious Hard to believe, but this quote was made over goal of providing a data model for interoperability twenty years ago by Charles Thornton and Emmanuel for the entire building industry. IFCs greatest suc- Valivaskis in the ASCE Computing Journal. This cess has been in adoption by BIM physical modeling article looks at some of what has been done to products, particularly® the IFC2x3 Coordination address interoperability in the Structural Software View (for review and coordination) with over 100 (SSW) Industry, asks why we are not quite there certified implementers. There are multiple ongoing yet, and postulates on some of the directions the IFC Extension efforts by special interest groups to industry is taking to address interoperability. fill in the gaps in IFCs data models. These projects and the mechanism to initiate such a project are TheCopyright Road Travelled well defined (see buildingSMART website noted in the online version of this article). While IFCs are Structural software typically continuing to be developed, there is work ongoing Structural Software communicates information in identifying subsets of the IFC data that is required Interoperability in one of two ways. Products to facilitate specific workflows between products. either interoperate indi- These subsets of the data are commonly referred to rectly, passing information as Model View Definitions (MVDs). Several MVDs By Raoul Karp, S.E. through an intermediate common format most have already been defined, including the previously often an Open Standard format; or directly with mentioned Coordination View and also a Structural product-to-product communication, most often Analysis View for interoperability mainly between with vendor (proprietary) solutions. analysis products. magazineIFCs weaknesses include some gaps in the data S T R U C T Umodel thatR already Eexist in competing standards Open Standards (see Robert Lipman’s NIST article on the CIS/2 To efficiently move information from multiple IFC Gap Analysis), relatively few certified MVDs, SSW products to each other, a lingua franca is the slow pace of consensus building to evolve needed, a common data format that each product standards and create MVDs and, similar to CIS, can read from and write to. AutoCAD DXF could the flexibility for vendor implementation that can Raoul Karp, S.E. is Director be considered the first such format in our industry. cause interoperability issues. of Product Management in the The richness of information contained in software Integrated Engineering Group today has outgrown the DXF standard, and many Direct Interoperability at . Raoul has different organizations have been urgently trying to published several articles on the fill the gaps through development of more robust It is often the case, for strategic or technical reasons, evolution of design and software Open Standards. Within our industry, two stan- that a direct product-to-product link provides the interoperation and participated dards – namely CIMSteel (CIS/2) and Industry best or only interoperability option. These direct in industry initiatives such as Foundation Classes (IFC) – have achieved the links often have the advantage that they can share ATC-75 for Structural IFC widest market adoption. Both these standards are additional data and intelligence that may not be definition. He can be contacted typically exposed as a file import/export option in available through an open standard. at [email protected]. popular structural software. While direct links are common in the industry and offer competitive advantage in some cases, this CIMsteel (CIS/2) solution is not scalable and is difficult to maintain by software vendors as the number of products increases. Computer Integrated Manufacturing of Constructional Steelwork Standard is possibly Are We There Yet? the most commercially successful of all current standards in the SSW industry. CIS/2 is a robust Despite significant work in development of stan- standard covering all things steel, from gross geome- dards for interoperability, it remains the single try to, literally, the nuts and bolts. The CIS standard largest impediment to increased productivity has three different models: Analysis, Design, and in our industry (McGraw Hill SmartMarket). Manufacturing. It is important to understand which Unlike traditional 2D CAD, when dealing with

32 December 2011 STRUCTURE magazine objects, attributes and their relationships in in CIS/2 and IFC. You need to understand detection, scheduling, and more are provided a 3D Model, the differences between how which version that each of your products by others including ’s © products manage data becomes significantly can produce and consume. Saying a product and Bentley Systems’ Navigator products. more divergent and complex. is CIS or IFC compatible is sometimes only However, as long as there are software com- Physical vs Analytical Models half the story. panies that hold dominant positions in the Roundtrip Interoperability market or that produce multiple products in Depending on the domain problem being one or more market segments, the incentive addressed, some structural software may The real power of interoperability is evident to provide tight, direct links will exist and require the absolute true life physical loca- when a product can continue to synchronize continue to be developed. tion and extents of a structure (for drawings, updates of models over time. This technique There is also precedence in other industries, clash, or detailing), while others are looking requires vendors to manage change between such as with JT Open in the mechani- for an acceptable simplification of the struc- subsequent updates. Some vendors like cal industry, for a collaborative approach ture (analysis for example). The interoperation , , and Autodesk have pro- amongst software vendors to create a between two products with this fundamen- vided technology to allow the user to manage platform for interoperability. This system tal difference in data format is a challenge. change at the individual object level from pulls together the best parts of the direct Some vendors have decided to create products within their products. Others like Bentley approach (an API)® and indirect approach where both physical and analytical models are Systems’ Integrated Structural Modeling (common intermediate model). Bentley’s produced together (, Tekla manage the change in a standalone synchro- Integrated Structural Modeling Platform Structures, Nemetsheck SCIA, and Bentley nization product. It is important to confirm (ISM) provides similar advantages of visu- AECOsim for example). The end-user is then if full round-tripping is possible with the alization, change management, revision required to be skilled in both disciplines to product and standard in use, and not just history, and interoperability through a strict effectively create models with these tools, and assume it is. Copyright API or Open Standards. ISM is address- facilitate appropriate interoperability and ing Bentley’s own internal interoperability keep these two models in sync. Next Stop? needs, as well as providing a platform for Where both physical and analytical models other vendors to integrate and realize all are not available in a single product, the The need for improved interoperability is the aforementioned benefits. burden falls on the software vendor to appro- not going away, but vendors consistently “Only when the barriers of integration priately infer one from the other during have to make investment decisions that pit and compatibility are removed will we be interoperation; in many cases this requires Open Standard development priorities against ready to cross the final hurdle, to deliver hands-on decision making by the end-user, Direct API links. our analysis and designs to the constructors effectively slowing down and making the On the Open Standards front, IFC is directly from our computers to theirs.” interoperability less efficient. In general, there likely to garner more and more of the atten- Thornton/Valivaskis has been greater market success interoperat- tion.magazine Companies like Tekla, Nemetsheck, ing between products that Sutilize theT same RSolibri, andU Data DesignC System T also pro-UWhile R much hasE been done, there is much fundamental data type model, be it physical vide free tools like BIMsight, IFC Viewer, still to do to realize Thorton’s and Valivaskis or analytical. Model Viewer, and DDS Viewer to allow vision of interoperability. This challenge is Data Intelligence – Lowest visualization and coordination between IFC as significant and pertinent today as it was ▪ Common Denominator models. Similar tools with capabilities of clash twenty years ago. With Open Standards, we must under- stand that the modeling intelligence that PIT, LITE and PDA a product may associate with its data will be lost in translation. For example, an Part of your toolkit for reusing existing foundations ADVERTISEMENT - For Advertiser Information, visit www.STRUCTUREmag.orgADVERTISEMENT Information, - For Advertiser elevator shaft object that pierces a slab creating an opening, or framing member PIT tests for layout relationships, are typically not concrete quality and part of the information shared between unknown length products. The user should consider this LITE evaluates when deciding where they want to model depth of steel piles their data such that it is most efficient for them. PDA assesses

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Open Standards allow vendor interpre- PDA tation and flexibility in how some data is specified. Some vendors choose to implement multiple versions of the Open Standard, each one targeted as a specific Cleveland, OH USA product and its particular implementation +1 216-831-6131 LITE PIT (flavor) of the standard. Similar issues can arise with different implementation levels www.pile.com [email protected]

STRUCTURE magazine33 December 2011 References 1. State of Automation in Structural Engineering – Progress Made and Still Issues Persist, ASCE Journal of Computing in Civil Engineering, vol.5 No.2 April 1991, Charles Thornton and Emmanuel Valivaskis.

2. buildingSMART International Ltd., IFC Standard, http://buildingsmart-tech.org/

3. buildingSMART International Ltd., IFC Implementers, http://buildingsmart-tech.org/implementation/implementations

4. buildingSMART International Ltd., Model-View Definitions, http://buildingsmart-tech.org/specifications/ifc-view-definition

5. Modeling Structural Steel: CIS/2 – IFC Gap Analysis, National Institute of Testing and Standards, NIST, January 10, 2011, Robert Lipman, www.nist.gov/el/building_environment/cibp/upload/CIS2_IFC_Gap_table.pdf

6. Interoperability in the Construction Industry, SmartMarket Report, McGraw Hill Construction, 2007 interoperability Issue, http://bim.construction.com/research/ ®

7. ArchiCAD, GRAPHISOFT Worldwide, Group, www.graphisoft.com/products/archicad/open.html

8. Structural Synchronizer, Integrated Structural Modeling (ISM), Bentley Systems, http://communities.bentley.com/products/structural/w/structural__wiki/integrated-structural-modeling-home.aspx Copyright 9. TEKLA BIMsight, TEKLA International, www.teklabimsight.com/index.jsp

10. IFC Viewer, Nemetschek Group, www.nemetschek.com/en/home/the_company/strategy_philosophy/innovation.html

11. Solibri Model Viewer, Solibri, Inc., www.solibri.com/solibri-model-viewer.html

12. DDS-CAD Viewer, Data Design Systems, www.dds-cad.net/132x2x0.xhtml

13. IFC Freeware tools, www.ifcwiki.org/index.php/Free_Software 14. JT Open, Siemens AG, www.plm.automation.siemens.com/en_sg/products/open/jtopen/program/index.shtmlS T Rmagazine U C T U R E

STRUCTURE magazine34 December 2011