Dynamic Reliability Analysis on Pounding of High-Pier Bridges Subjected to Stochastic Seismic Excitations
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摘要: 为了研究不同地震动强度作用下高墩桥梁的碰撞可靠度的不同，在频域范围内提出了一种以虚拟激励法为基础的动力可靠度计算方法，依托某高墩大跨度桥梁为工程背景，分析了高墩桥梁在不同地震强度下的碰撞可靠度.选择反应谱的水平加速度作为地震强度衡量指标，且将不同强度指标的反应谱转化为相应的功率谱；利用虚拟激励法求解随机振动方程，得到结构响应的均值与均方差值，再基于Davenport理论获得结构峰值响应的期望和标准差；根据首次超越理论计算梁体碰撞可靠度.研究表明：地震动加速度小于0.22g时，梁体之间不发生碰撞，动力可靠度为1.0；加速度大于0.22g时，梁体碰撞动力可靠度下降明显，即在强震作用下，梁体发生碰撞.Abstract: A dynamic reliability analysis based on the pseudo-excitation method in the frequency domain was proposed to investigate the pounding reliability of high-pier bridges subjected to seismic excitations with different ground motion intensity levels. A high-pier bridge was selected as the numerical example and the pounding reliability of the high-pier bridge was computed for each ground motion intensity level. The horizontal acceleration response spectrum was chosen as the seismic intensity measure and the response spectra for different intensity measures were converted into the corresponding power spectra. Next, the stochastic vibration equation was solved using the pseudo-excitation method to determine the mean and mean square deviation of the structural dynamic responses. The expected values and standard deviation of the structural peak responses were obtained using Davenport's theory. Finally, the pounding reliability between the adjacent beams of the high-pier bridge was determined using the first passage theory. The results indicate that pounding will not occur between the adjacent decks and the pounding reliability is 1.0 when the ground acceleration is less than 0.22g. In addition, there is an obvious decrease in the pounding reliability such that the structure collides under the strong ground motions when the ground acceleration is more than 0.22g.
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表 1 动力特性
Table 1. Dynamic characteristics
阶数 频率/Hz 振型 1 0.71 主桥纵向振动 2 0.92 主桥横向振动 3 1.02 引桥纵向振动 4 1.35 全桥对称横向振动 5 1.38 主桥横向振动 
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