Abstract：When the Caughey damping matrix is constructed by traditional method, how to choose reasonable multi-reference frequencies and avoid negative modal damping ratios are challenges. Therefore, based on the seismic response spectral analysis, using the error of peak displacement as the objective function and making the modal damping ratios larger than zero as constraint condition, an optimal solution of Caughey damping coefficients is proposed by constraint quadratic programming. Then, a dome structure with 90m-diameter and 15m-height is analyzed to illustrate the necessity of Caughey damping when there are many significant contribution modes and the difference in natural frequencies of significant contribution modes for different response are great. Meanwhile, the traditional method and the optimal method are compared in the effects on structural seismic response errors. Numerical results show that the traditional method ignores the difference in different modal contributions to choose reference frequencies and cannot control the errors of dynamic responses effectively; the optimal method makes the damping ratios of significant contribution modes reasonable and the errors from the optimal method is smaller than that of the traditional method for more than 4 Caughey series.
2015, Vol. 36 
