The Conestogo River Bridge—design and testing

Abstract

The bridge is a three-span continuous steel plate girder structure with a concrete deck slab that is longitudinally prestressed for full composite action. It was selected as a development bridge to incorporate a number of recent research findings and new design techniques.The design live loading was modelled on the observed truck loadings in Ontario, and a grid analysis and a new load factor method were employed for design. The usual specification deflection and impact values were abandoned in favour of a dynamic analysis, resulting in the selection of a very flexible structure with a low natural frequency. Other features include the use of high strength bolts as shear connectors and of slab test panels designed for membrane action with greatly reduced reinforcing steel.The paper describes the initial research, the design features and procedures, the instrumentation of the bridge, and the test programme using two load test vehicles each of which could be loaded to 200 kips (90.72 t). The testing and results are reviewed, and the significant findings are related to the design assumptions and the earlier research. Initial evaluation of the test data indicates that the dynamic testing results and the slab testing results in particular promise to have considerable effect on future designs.