Stability and Serviceability Optimization of Footbridges

Abstract

This dissertation investigates solutions to the top chord stability problem inherent to steel pony truss footbridges, as well as the serviceability issues of pedestrian-induced vibration and midspan deflection. A framework for describing sustainable footbridge design is established to define the developed approaches and methodologies. A novel analytical approach to defining the geometrically nonlinear behavior of these structural systems is proposed to explore the correlation between in-plane stiffness distribution and the in-plane stability behavior of steel pony truss footbridges. Two methodologies are presented that pair computational form-finding and shape optimization algorithms to produce novel forms for steel pony truss footbridges, which yield improved stability and serviceability performance in comparison to conventional configurations. These methodologies are validated using two-dimensional and three-dimensional case studies containing novel forms for three types of pony truss structural systems, two sets of boundary conditions, and two structural section sizes. Relationships between form, force, and function are established from the optimized footbridge forms generated using the presented methodologies.