Long-Span Pedestrian Bridges in the USA: A Futuristic Approach

Pedestrian bridges have historically provided engineers and architects with opportunities to push the envelope in terms of engineering concepts, analysis and design techniques and technology, materials and aesthetics. The challenges they present-from spanning long distances and vibration control to the construction logistics associated with the space being bridged-have led to a plethora of iconic structures. This trend continues today, driven-in addition to the traditional impetus to innovation-by the current focus on sustainability, resilience and the availability of new computational optimization tools. This emphasis invariably results in the economic usage of materials and structural resilience, and this focus is expected to continue to influence the approach to the design of pedestrian bridges in the future. This paper presents examples of two box-girder/orthotropic pedestrian bridges designed to optimally meet the challenges posed by their respective site and functional constraints in regions of high seismicity. These bridges are under construction or have recently been completed. Also presented are conceptual studies for a pedestrian bridge at the Los Angeles International Airport (LAX), the design for which was developed using computational structural optimization techniques. Such techniques have already been successfully applied to structures in the aeronautical, automobile and mechanical industries, in which natural force flows are modeled. Two optimization techniques were utilized leading to two unique design solutions.