基于汶川地震发生时自贡市西山公园地形影响台阵的加速度记录,利用双向反应谱比法分析了山脊地形对单自由度体系结构反应的放大效应,结果表明:(1)水平向结构反应在结构自振频率小于1Hz的低频段放大效应不明显;在1～10Hz频段山顶放大效应最大,最大值达3.25,对应频率为6.25Hz;在10～20Hz频段,各台站放大效应趋于平稳,靠近山顶的7号台站放大效应最明显,最大值为2.3,对应频率为16.7Hz。(2)结构反应的最大放大系数有随高度的增加而增大的趋势,且在1～10Hz频段这种趋势比较明显。(3)与其它场地效应估计方法相比较,该方法能够体现地形效应对结构反应的影响,从而更有利于研究建筑结构震害的分布。

Based on the strong ground motion accelerations recorded by the topographic array in Xishan park of Zigong city for the mainshock of the Wenchuan earthquake，the amplification effects of SDOF system ( damping ratio ζ = 5%) located at the mountain ridge topography were studied with the bidirectional response spectra ratio method，and the results are as follows: ( 1) The amplification effect of topography on horizontal structure is not obvious when frequency is below 1Hz． In the frequency range from 1Hz to 10Hz，the amplification factor of hilltop is maximal，the maximal amplification factor is 3. 25 and the corresponding frequency is 6. 25Hz． In the frequency range from 10Hz to 20Hz，amplification effect of each station tends to be steady， the amplification factor of Station No. 7 in the vicinity of hilltop is maximal，the maximal amplification factor is 2. 3 and the corresponding frequency is 16. 7Hz． ( 2 ) The maximal amplification factors of structure response tend to increase with the elevation of the hills，and the trend in frequency range from 1Hz to 10Hz is more obvious． ( 3 ) Compared with other siteresponse estimation techniques，this method could reflect the influence of topography on structure， which is a better way to study the seismic damage distribution of structures．

国家自然科学基金项目(51078323)