Cadalyst - August 2008 - (Page 42)

aecinsight as Design Master or IES VE, absent Revit MEP, but cannot accomplish that complete workflow in Revit MEP absent an analysis and documentation package. What the building engineering flavors of BIM model-authoring tools really provide is the ability to round-trip building information from architectural models to engineering analysis tools and back again with engineering-sized components to reintegrate and coordinate with the architectural model. Some tools now offer extended capabilities to integrate certain aspects of engineering analysis directly into the architectural design process for more interactive feedback to architects about the engineering effects of their design decisions. This approach was pioneered by Ecotect and by Green Building Studio (both now owned by Autodesk), as well as the various toolkits offered by IES as plug-ins to Revit MEP or Revit Architecture. Structural Strictures Figure 2. After electrical loads have been calculated as part of a BIM workflow, electrical distribution systems still are documented with traditional one-line diagrams. Here, Design Master Electrical integrates AutoCAD drafting data directly with engineering calculations. (Courtesy of Design Master Software) In fact, one of the key roles played by programs such as Revit Structure and Revit MEP is the reformatting of building information from the architectural model-authoring tool (Revit Architecture) into a an arrangement suitable for input to pre-BIM and/or BIM-adjacent engineering analysis tools. In an architectural BIM model, for example, a column typically appears as a spatial object composed of the actual structural element (steel, concrete, or timber) surrounded by appropriate fireproofing and/or blast-proofing and its finish materials. In a structural analysis model, however, that same column most often is represented by its centerline as the basis for the application of loads and forces. Similarly, the representation of concrete in an architectural BIM modelauthoring tool typically omits reinforcing steel within concrete elements and treats an entire concrete structure as if it were a single, monolithic element, rather than a composite assembly made of numerous lifts and pours. Round-Trip Transportation On the MEP side, architectural BIM models rarely reflect the kind of partitioning into spatial volumes and surfaces that is required as input to whole-building energy analysis packages such as the U.S. Department of Energy’s EnergyPlus energy simulation software. This repartitioning of architectural models into an arrangement suitable for analysis is one of the key functions of software such as Revit MEP, but the actual engineering analysis likely is performed in a program such as IES Virtual Environment (VE, figure 1, p. 41) — a tool that contains its own modeling capabilities and can perform very nicely and completely without input from Revit (or any other architectural or MEP model-authoring tool). Interestingly, for both structural and MEP analysis, the reverse workflow doesn’t hold true. In other words, an MEP engineer can accomplish most if not all the necessary design and documentation workflow in tools such 42 On the structural side, where many analysis packages are available, a trend for CAD/BIM vendors has been to snap up previously independent software programs. In recent years, Bentley has acquired the likes of RAM and STAAD, and Autodesk picked up Robobat. Because engineers may favor one analysis package for their internal workflow, yet have a model-authoring suite dictated by the project, these acquisitions have led to some interesting mix-andmatch possibilities. In fact, facilitating cross-platform workflows was among the initial motivating factors for efforts in interoperability such as the Industry Foundation Classes (IFC) standard, now popularly known by a catchier name: buildingSMART. Tekla makes one of the most interoperable structural solutions that addresses detailing and fabrication more specifically than analysis and modeling, per se. In fact, Tekla often is an integral part of the standard workflow from design engineer to detail engineer, fabricator, and erector — independent of other analysis and modeling tools — whether in precast concrete, cast-in-place concrete, or steel structures (the latter in accordance with the CIS-2 standard for steel design and detailing workflow). BIM engineering modeling tools also provide the ability to reintegrate engineer-designed building content with the architectural BIM model, for purposes of clash detection and the like. Of course, many projects neither need nor can justify modeling or remodeling of all engineered content in a multidiscipline, coordinated BIM model. For example, flexible ducting, piping smaller than a certain diameter, and most electrical distribution systems (figure 2) typically are not modeled as full 3D components. Overall, the extent to which building engineers integrate BIM automation tools into their workflow depends at least as much on practical choices about round-trip information exchanges with architects using BIM model-authoring tools as on any inherent benefits to themselves. Industry analyst and consultant Jerry Laiserin helps AEC/O businesses — and the technology providers who serve them — build smarter through the integration of technology strategy and business process. E-mail him at jerry@laiserin.com. www.cadalyst.com cadalyst August 2008 http://www.cadalyst.com

Table of Contents Feed for the Digital Edition of Cadalyst - August 2008

Cadalyst - August 2008 Contents Editor's Window CAD Central Tech Trends: Rotor Bug Strikes Again Cadalyst Labs Reviews: Digital Dreams — Visualization Software: Make Your Design Visions a Reality Maple 12 — Math Software AutoLINE 2009 — Linetype Management Add-On Deep Access — Digital-Media Asset Management Software View Point: Examining the Autodesk–Bentley Agreement CAD Manager: Managing Multioffice Mayhem MCAD Modeling: Do You Need Modeling Standards? AEC Insight: Modeling Technology for Building Engineers CAD Cartoon Issue Indexes Hot Tip Harry: Better Living with Objects and Smart Entities

Cadalyst - August 2008

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