The Year in Infrastructure 2007 - (Page 71) ciVil structural analysis, design and dOcumentatiOn This category features projects that illustrate creative and effective uses of information-based approaches in the structural engineering process. Of particular interest are projects in which analysis, design, and documentation of the structural system were integrated. winner Marina Bayfront Pedestrian Bridge arup The Marina Bayfront Pedestrian Bridge in Singapore is the first of its type in the world. At 280 meters long, the bridge features a unique doublehelix exoskeleton constructed from stainless steel, which gives structural support to a 6-meter-wide deck spanning 65 meters between piers. By balancing the unraveling forces of the opposing helices, the bridge is being constructed out of significantly less steel. The bridge curves in plan view while in elevation rising to a high point in the center to allow ships to pass underneath. Designers had to provide sufficient clearance for the shipping lane below, but also keep the slope gentle enough for pedestrian traffic. Other design considerations included the need for a link to a nearby vehicular bridge and a passage for pedestrians under the bridge at each abutment. Using a 3D model enabled designers to understand the complex geometry and create drawings suitable for cost estimating and construction. Arup was able to minimize construction costs by approximating the double-curved helix geometry with a series of single-curved planar segments. Initially, the helix tubes all had slightly different bend radii. Using macros and spreadsheets, designers developed a new curve geometry that used only one bend radius for each of the two spirals that formed the double helix. This, in turn, cut the time needed to bend the steel and reduced the amount of waste. The central workflow featured a streamlined flow of information between various packages used in the design process. Bentley’s GenerativeComponents allowed the Arup team to begin modeling the complex detail geometry even before the final geometry was finalized. Import/ export facilities of the software allowed Arup to analyze the geometry in a number of ways and provide accurate information to internal and external parties in an easy-to-understand format. Other software deployed included MicroStation, InRoads, and Bentley Structural. BE AWARDS OF EXCELLENCE 71
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