Abstract: In order to make the frequency independent hysteresis damping in site seismic response analysis equivalent to the viscous damping for time domain analysis, an optimization method is proposed to optimize the conversion frequency of hysteresis damping, and on this basis, the optimization method of equivalent Rayleigh damping calculation is constructed. Firstly, the objective function is constructed by minimizing the cumulative acceleration error of the equivalent viscous damping system of the single degree of freedom hysteretic damping system, and the optimization algorithm of the hysteretic damping conversion frequency is established. Then, taking 21 seismic waves as input, the effects of natural frequency, hysteresis damping ratio and dominant frequency on the hysteresis damping conversion frequency are analyzed statistically. The results show that the optimal conversion frequency of hysteretic damping is mainly affected by the natural frequency, while the influences of hysteretic damping ratio and dominant frequency are very small. On this basis, taking the minimum ground acceleration response error as the objective function, the constrained optimization equation for solving Rayleigh damping coefficient is established. Finally, taking the seismic response of a valley site as an example, the computational accuracy of the proposed method and the traditional Rayleigh damping structure method are analyzed and compared, and the accuracy and effectiveness of the proposed method are verified.

Key words: site response, hysteresis damping, Rayleigh damping coefficients, hysteretic damping conversion frequency, optimization method