Analysis, Design & Performance
Full Session with Abstracts
335009-2 - Structural Optimization for Efficient Bridge Designs: The Prototype for the LAX Pedestrian Bridges
Saturday, April 21
10:00 AM - 11:30 AM
The design of pedestrian bridges has been evolving significantly in the past few years due to emerging technologies and the application of non-traditional materials. This paper describes these trends with specific reference to the design of a prototype for the Los Angeles LAX airport pedestrian bridges. The design for the bridges was developed using structural optimization techniques, which have already been successfully applied in the aeronautical, automobile, and mechanical industries where natural force flows are modeled. These fundamental principles of optimization have been used to develop two novel responses to the long-span pedestrian bridge – the optimized orthotropic plate pedestrian bridge and the optimized truss pedestrian bridge. Both designs, though unique and simple, integrate the idea of topology optimization with modular design, resilient materiality, sustainable practices and visual transparency. By focusing the design effort of the bridge on structural optimization and weight reduction, the corresponding seismic forces have been reduced as well. The Optimized Orthotropic Plate Pedestrian Bridge is comprised of a lightweight steel-plated structure from which the walking deck is suspended. The steel material is located where it is utmost required allowing for steel cutouts which also serve as skylight for the bridges. The openings enhance the visual transparency. The Optimized Truss prototype utilizes the full height of the bridge for the structural truss depth, thus structural stiffness is maximized while material volume is minimized. The aerodynamic oval shape maximizes the walking surface while reducing wind loads. For both prototypes, the main structural module is expandable in the center, allowing for adaptability to the various spans occurring at the airport. This paper summarizes the design techniques, prefabrication and connection details for both bridge prototypes.