EQUIVALENT KELVIN IMPACT MODEL FOR POUNDING ANALYSIS OF BRIDGES DURING EARTHQUAKE

A method to determine the parameters of Kelvin impact model for pounding analysis of bridges during earthquake is proposed. Based on Hertz contact theory and considering the wave effect, the impact stiffness of Kelvin impact model is determined according to the ratio of maximum impact load to maximum contact deformation. The recovery coefficient of pounding between adjacent girders, which influences the sampling of the damping coefficient of Kelvin impact model, is numerically analyzed. The results indicate that the impact stiffness of Kelvin impact model increases with an increase in the Hertz contact stiffness, the impact velocity, and the length ratio of the short to long girders. The wave effect has remarkable influence on the impact stiffness and can not be neglected. The recovery coefficient of pounding between adjacent girders decreases with an increase in the impact velocity, but with a decrease in the length ratio of the short to long girders. The rational sampling ranges of the impact stiffness of Kelvin impact model and the recovery coefficient of pounding between adjacent girders for urban bridges are found to be 3×105 kN/m―6×105 kN/m and 0.6―0.95, respectively.