Study On Mechanical Behaviors Of Reinforced Concrete Bridge Piers Wrapped With Steel Plates After Corrosion

Considering viaducts as an important part of transportation network, it will determine if the relief supplies can be smoothly transported into the stricken area and the injured people can receive treatment in time during severe earthquake. Therefore, the security of viaducts plays an important role in seismic design. Many surveys show that serious damage or even collapse of bridge during an earthquake is mainly due to the destruction of the piers. Because reinforced concrete bridge piers are liable to damage near the pier base during the earthquake, bonding steel plates outside the reinforced concrete piers is widely used as a retrofitting method. However, corrosion phenomenon of steel plates is often observed due to water logging or corrosion environments. To what extent the corrosion affecting the piers needs to be carefully studied through experiments and numerical analytical method.The object of this study is the reinforced concrete bridge piers wrapped with steel plates. Two-dimensional and three-dimensional elasto-plastic finite element formulation are employed to investigate the effect of corrosion mode and steel plate-concrete bonding behavior on the lateral bearing capacity and hysteretic behavior of the piers, which corrode at the pier base. The main contents and conclusions of this thesis are as follows:(1) Two-dimensional elasto-plastic finite element formulation is employed to investigate the effects of steel plates’ corrosion rate and corrosion mode on the lateral bearing capacity of the pier. It is observed that lateral bearing capacity decreases with the increase of steel plates’ corrosion rate. The degradation of the lateral bearing capacity resulted from the web’s local corrosion mode is more serious than that under even corrosion mode.(2) Three-dimensional elasto-plastic finite element formulation is employed to investigate the effects of steel plates’ corrosion position, corrosion depth along thickness direction, corrosion range and steel plateconcrete bonding behavior degradation on the lateral bearing capacity of the piers. It is observed that the small-scale local corrosion along height direction does little effect on the lateral bearing capacity of the pier. When the corrosion occurs at the base of web, the degradation of the lateral bearing capacity is closely related to steel plates’ corrosion position, corrosion depth along thickness direction and corrosion range. When the corrosion appears at the base of flange, the degradation of lateral bearing capacity is related to steel plates’ corrosion depth along thickness direction and the corrosion range. The cooperative ability between steel plates and concrete, as well as the lateral bearing capacity of the piers decrease with the continued degradation of steel plate-concrete bonding behavior.(3) Three-dimensional elasto-plastic finite element formulation is employed to investigate the corrosion status and bonding behavior degradation of steel plate-concrete interface on seismic performance of the piers on the basis of envelop curves, ductility factor, stiffness degradation factor and equivalent viscous damping coefficient. It is concluded that the seismic performance decreases with the increase of corrosion status, and the seismic performance increases with the improvement of steel plate-concrete bonding behavior. The research findings are expected to provide a useful reference for the maintenance and strengthening of the in-service piers.