Strain rate effect on dynamic response of bridge piers in high-speed railway under the earthquake loading

Both concrete and steel are sensitive to strain rate, and the high strain rate caused by earthquakes will improve the material property including the strength and elasticity modulus. While analysing the dynamic response of bridges under the earthquake loading, there are some certain errors based on static constitutive model. By the method of dynamic increasing factors (DIF) of concrete and steel, the dynamic responses of bridges in high-speed railway were analysed in fibre beam-column element models to study the strain rate effect, and the reasonable uniaxial constitutive model of concrete and steel were used in the numerical simulation. The results show that the maximum moment at the bottom of pier calculated by quasi-static constitutive models is less than that calculated by constitutive models considering strain rate. Compared with the dynamic constitutive models considering strain rate, the larger curvature at the bottom of the pier and displacement at the top of pier were obtained in the analysis on the basis of quasi-static constitutive models. The strain rate has less effect on the dynamic response before the piers yield, and the effect can be ignored. While the earthquake loading can cause piers to fail or collapse, the strain rate effect needs to be precisely considered.