Improve the Lateral Stability of Variable Height Steel Truss Type Pedestrian Bridges in Sri Lanka

Abstract

This paper investigates the methods of improving the lateral stability of variable height truss type steel bridges that are used for pedestrian purposes in Sri Lanka. Several truss type steel bridges have been built for pedestrian use in the recent past. Modified Warren and variable height bridges can be commonly seen in the Southern Province of Sri Lanka related with the major river crossings. When designing a pedestrian bridge for local conditions, it is very important to consider the loads due to pedestrians, wind and sometimes light weight vehicles in the rural areas. So it is preferred to investigate the applicable truss types and their shortcomings by conducting a detailed analysis. The aim of this research is to provide an overview of the Finite Element (FE) method with the focus on lateral stability of the variable height steel truss type pedestrian bridges, their analysis and various applications. Span vs. tonnage graphs were developed for variable height (Tied Arch) and Inverted Arch bridges incorporating circular hollow, rectangular hollow and concrete infilled sections for the top chord members. Results from this study indicated that both Inverted Arch and the Tied Arch bridges with concrete infilled sections consume considerably less steel tonnage.