汶川地震动衰减特性及其大跨高墩连续刚构桥的地震响应规律

为分析不同断层距下，汶川地震动对大跨高墩连续刚构桥的作用效应演变规律，收集了全国129个汶川主震地震台站记录。从工程地震学角度，分析了汶川地震动记录强度指标的衰减特性，总结了PGA、PGV和反应谱的衰减规律。以庙子坪大桥主桥为工程背景，构建了两类不同墩高形式的大跨连续刚构桥梁样本组，对两类桥梁自振周期的代表值进行了对比讨论和分析|基于反应谱分析，拟合得到两类桥梁响应谱随断层距变化的峰值响应曲面，讨论了不同断层距，大跨高墩连续刚构桥的响应特点。研究表明，不同断层距的大跨高墩连续刚构桥梁的地震响应具有明显差异，近断层地震响应明显强烈。研究成果可为大跨高墩连续刚构桥的桥墩布置形式和桥址选择提供借鉴和参考。

Ground motion attenuation characteristics of Wenchuan earthquake and seismic response law of long-span continuous rigid frame bridge with high-rise pier

In order to analyze the evolution law for the action effects of long-span continuous rigid frame bridges with high-rise piers under the actions of Wenchuan ground motions with different fault distances, mainshock records of Wenchuan earthquake from 129 national seismic stations were collected. Attenuation characteristics for the intensity magnitudes of Wenchuan ground motion records were analyzed from the viewpoint of engineering seismology, and then the attenuation laws of PGA, PGV and response spectrum were summarized. With the main bridge of Miaoziping bridge taken as the example, two kinds of sample groups for long-span continuous rigid frame bridges with different pier heights were produced, and the representative values for natural periods of these two kinds of bridges were compared and discussed subsequently. Based on the response spectrum analysis, the peak response surfaces, which changed with different fault distances for the response spectra of these two kinds of bridges, were fitted, and then the response characteristics of the long-span continuous rigid frame bridges with high-rise piers for different fault distances were discussed. The results show that for different fault distances, the seismic responses of long-span continuous rigid frame bridges with high-rise piers are significantly different, and the seismic responses of these two kinds of bridges under the action of the near fault ground motions are obviously strong. The research results provide the guidance and reference for the layout of piers and the selection of bridge site for the long-span continuous rigid frame bridge with high-rise piers.