【作者】 王蕾；

【导师】 赵成刚； 屈铁军；

【作者基本信息】 北京交通大学 ， 防灾减灾及防护工程， 2010， 博士

【摘要】 地震波在传播过程中具有行波效应、部分相干效应、场地效应和衰减效应。山脊地形对地震地面运动有放大作用,对建于复杂山区场地中的大跨桥进行地震响应分析应考虑地形条件的影响。曲线型桥由于几何特征的复杂性,动力性能有别于直线型桥。合成更接近实际情况的考虑空间变化特性的时-频非平稳地震动,对曲线桥在多点激励下的抗震性能进行理论分析和大尺寸空间结构模型的模拟地震振动台试验研究可为评价大跨桥的抗震性能以及今后同类结构的抗震设计提供理论和试验依据。本文针对这些情况,主要进行了以下几个方面的研究：1、考虑地形效应的多点地震地面运动。将3条具有不同频谱特性的实际地震记录分别以P波、SV波的形式以不同角度入射,计算出两座山峰及其间自由场地的加速度、速度、位移时程。得到了包含地震波传播时山体散射和行波效应综合影响的地震动场。2、复杂地形条件下大跨刚构桥多点激励下的地震响应分析。将得到的考虑地形与行波综合影响的地震动作为输入,以建于两山之间的总长440m的4跨连续刚构直线型桥为例,对大跨桥的地震响应进行了数值模拟,并与忽略地形影响仅考虑行波效应时的计算结果进行对比分析。指出抗震设计中考虑地形效应影响的必要性,从而为连续刚构桥的工程应用及提高抗震安全性提供理论依据。3、人工合成了非平稳地震动场并进行了曲线桥在多点地震动激励作用下的动力响应分析。用相位差谱表征地震动频率的非平稳特性；用相干函数表征地震动空间变化的部分相干效应；采用随频率变化的等效相速度代替随意给定的视波速表征地震动的行波效应,生成了具有强度和频率非平稳特性的多点地震动场。将这种考虑时间和空间变化的地震动沿水平和竖向分别作用于5跨连续刚构曲线桥桥墩基础上,计算了墩顶位移及墩底内力,并与一致输入、特定视波速下曲线桥计算结果进行比较。分析了大跨曲线桥多点输入下部分相干效应和行波效应对结构动力响应的影响。4、多点激励下大尺寸曲线桥结构模型的模拟地震振动台试验研究。在相似理论的基础上,对曲率半径R=620m,跨度68m+120m×3+68m的5跨曲线刚构桥原形制作了整体模型。利用北京工业大学9子台振动台台阵系统对模型桥进行了水平地震动振动台试验。通过试验得到了在多点激励地震动作用下该结构相应部位的加速度、位移、应变响应,并与相应的理论计算结果进行了比较。为评价大跨桥结构在地震作用下的抗震性能及今后同类结构的抗震设计提供了试验的基础和数据。更多还原

【Abstract】 There are some characters about the seismic in the process of propagation, such as wave passage effect, incoherence effect, site-response effect and attenuation affect etc. It has been verified that ground motion is obviously amplified along the ridge. Therefore, the topographic effect on seismic response of large-span bridge under complex landform must be considered. Due to the complex geometric character, the dynamic responses of the curved bridge are different from that of the straight one. Simulating the non-stationary spatial correlative time histories of multi-point ground motion, studying the seismic responses of the curved bridge under multi-point excitations, and simulating earthquake shaking table test for such large-scale spatial structures could provide a guideline to structural performance evaluating and a seismic design reference for curved bridge theoretically and experimentally. The main contents are as following.1. Generation of the multi-point earthquake ground motions considering the topographic effect.The seismic ground motions of two neighboring mountains and the free surface between them are calculated under the P and SV seismic waves with several different incident angles. The incoming waves are chosen from three actual earthquake records with different spectrum characteristics. The ground motion responses reflect a combined influence of ridge scattering effect and traveling-wave effect.2. Seismic responses of large-span rigid-frame bridge under multiple-point excitations and complex topographic conditions.The results derived from the first analysis stage were then used as the inputs in the second analysis stage. Taking a four-span rigid-frame straight bridge of 440m as an example, which was assumed to be built between two neighboring asymmetric mountains, the seismic responses of the bridge are numerically simulated, and the results were compared against those when only the wave passage effect is taken into account. A conclusion is given that the irregular topography will have significant effect on the wave propagation, which cannot be ignored in the seismic design. The conclusion provides an important theoretical reference for the engineering application and for improving the seismic safety of the continuous rigid-framed bridges.3. Simulation of non-stationary artificial ground motion and analysis of seismic response of curved bridge under multi-support earthquake excitations.The phase difference spectrum was introduced to consider the non-stationary properties of frequency contents, the statistic model of the coherence function was used to consider the coherence character, and the apparent wave velocity varying with the frequency of earthquake wave was adopted rather than an arbitrary one, the non-stationary random field considering the temporal-spatial variation was simulated. This random field was then used as the multi-point excitation of a five span continuous rigid-frame curved bridge in horizontal and vertical directions respectively. The pier-top displacement and the pier-bottom internal force of the bridge were calculated, and then the results were compared with those considering uniform and traveling-wave excitation. The influences of incoherency effect and the wave passage effect on the seismic responses of the bridge were discussed.4. Shaking table test on large-scale curved bridge model under multi-point excitation.The curved bridge is a five span structure of 68m+120mx3+68m total length. The curvature radius is R=620m. Based on similar theory, the whole model was made. The horizontal shaking table test of the model bridge by the multiple vibration table array system, located in Beijing University of Technology, was carried out. The acceleration, displacement and strain of the structure under the horizontal earthquake are gained. These test dates were then compared with the theoretical results. The results can provide test data and basis to evaluate the seismic performance of such curved bridge and can be a reference for seismic analysis of similar structure in future.更多还原