Optimum span length for a PCI-girder expressway bridge

ABSTRACT In the design of PCI-girder bridges, the application of various optimum design methodologies can result in significant cost savings and improved structural performance. However, most of the optimisation techniques focus on the individual components and the overall structural system of the superstructure of the bridge system. Limited studies are carried out in the context of longitudinal and transverse configurations of the members in a particular bridge system. This study identifies the optimum span for the PCI-girder expressway bridge system by adopting longitudinal and transverse arrangement of members as design variables while keeping the cross-section of the girder constant. Using an existing case study bridge structure located in Bangkok, selected parametric studies are carried out to achieve cost optimisation. It is observed that the optimum span range for the PCI-girder bridge is in the range of 25 m (82 ft) to 33 m (108 ft).