SEISMIC DESIGN OF BRIDGE PIERS

Abstract

This thesis studies the seismic design of bridge piers. An analytical model for predicting the stress-strain behaviour of reinforcing steel under dynamic cyclic loading was derived. A generalised stress-strain model for plain or confined concrete under dynamic cyclic axial compression loading is presented. To verify the model, axial compression tests were carried out on 15 circular columns with spiral reinforcement, 16 rectangular walls and 5 square columns with rectilinear hoops. In the case of both models theoretical predictions compare well with experimental behaviour. A ductile design methodology for bridges is presented. A theoretical model is developed to predict the lateral load-deformation behaviour, and thus ductility capability, of reinforced concrete columns under axial load and cyclic flexure. Design charts are prepared to enable the rotational capacity of columns with confined concrete to be assessed. An experimental investigation into the seismic performance of ductile hollow reinforced concrete columns is described, in which 40 percent full size specimens, containing different amounts of confining steel in the plastic hinge zone were subjected to constant axial load and cyclic lateral displacements. Member ductilities between 6 and 8 were obtained and no significant strength degradation under cyclic loading was observed. Predictions from the model are found to compare well with experimental results. (TRRL)