Response of tall-building steel structure to multi-dimensional seismic action

The general mode superposition procedure of the unsymmetrical structure under two dimensional seismic actions was first set up. Based on this, some questions which will be confronted in calculating the response of structure under two dimensional seismic actions by the response spectrum method were discussed. Time history analysis of many engineering examples under single dimensional component or two dimensional components of ground motion was performed. According to these numerical computations, the ratios among the maxima of seismic responses of structure under different cases were classified and compared in order to discuss the feasibility of substituting the seismic response under double components of ground motion with the combination of two seismic responses of single components of ground motion, and this conclusion was extended to the response spectrum method. Finally, a responses spectrum method of computing the seismic response under the multi dimensional components of ground motion is put forward for practice.