程序采用的是两层循环上实现位移谱的求取。内循环实现在地震波下由上一步所得到的位移、速度和加速度得到下一时间间隔后的位移速度和加速度；外循环实现在不同结构自振周期（频率）下遭遇地震波的响应。-Program uses a two-layer loop on calculate displacement spectra. Cycle based on seismic waves obtained　the previous step under the displacement, velocity and acceleration are next after the interval velocity and Acceleration outer loop implementation in different natural period of structure (frequency) the response under earthquake wave.