大跨度结构多点地震反应计算方法的比较

分析比较了直接求解法、位移输入法、相对运动法和大质量法4种不同多点地震动输入下大跨度结构地震反应的计算方法.以一实际工程为例进行了算例计算和结果比较，数值结果表明,直接求解法、位移输入法和相对运动法3种方法的计算精度较高，建议采用.大质量法计算结构加速度反应精度较高，但是位移和内力反应会出现严重的失真现象.位移失真原因主要是由程序中数值积分引起的，且大质量法并不能保证计算中的地震位移输入和实际的位移激励一致.
Four calculation methods for the seismic response analysis of the long span structure under the multi support seismic excitation, such as direct method, displacement input method, relative motion method and large mass method, are compared. Based on a practical project in Shanghai, an illustrative example using these four methods respectively is presented. Results indicate that the direct method, displacement input method and relative motion method are high fidelity calculation methods and are recommended to use. The acceleration response calculated by large mass method is accurate enough. However, the displacement response and internal force response calculated by large mass method are seriously distorted. Main reason of the distortion is produced by the numerical integration in the calculation procedure and the seismic displacement input during the analysis in large mass method can not be equal to the true seismic displacement excitation surely