近断层地震多维多点激励下斜拉桥倒塌过程及失效机理研究

As important transport junction, the destroyed of cable-stayed bridges under strong earthquake excitation will cause huge economic losses. The near-fault ground motion has some basic engineering characteristics, such as the velocity pulse, which are different from far field ground motion. Therefore, the structures usually have great seismic response under near-fault earthquake excitation. This project is aimed at disclosing the collapse mechanism of cable-stayed bridge under strong near-fault ground motion by means of theory, numerical simulation and lab experiment. It is intended to solve the spatial and multi-point near-fault seismic wave combination that can include velocity pulse, the time delay, partial coherence and site effect, and to establish the three-dimension finite collapse analysis model. The finite model can consider pounding between girders and impact effect of destroyed structure components. The project proposes the shaking table tests of cable-stayed bridge under spatial and multi-point near-fault seismic excitation in the laboratory. The experimental results will be used to verify the analytical model. Based on the verified finite model, parametric studies can be carried out to figure out the influence laws of velocity pulse, multi-dimensional excitation and multi point excitation on collapse of cable-stayed bridge. And the collapse and failure mechanism of cable-stayed bridge under strong near-fault ground motion is summarized in the end. In that mean, this project can provide basic theory for anti-collapse design for cable-stayed bridge under strong ground excitation.

斜拉桥通常是交通枢纽工程，一旦在地震中遭到破坏，将会造成巨大的经济损失。由于具有强烈的速度脉冲等特征，近断层地震动对工程结构的影响异于远场地震动，通常会对土木工程结构产生较大的破坏。本项目拟从理论分析、数值模拟和试验研究三个方面的深入地研究近断层强震作用下斜拉桥的倒塌失效机理。旨在解决能考虑脉冲速度特性、行波效应、部分相干效应及局部场地效应的近断层空间多维多点地震动的合成技术；建立能考虑主引桥碰撞及局部构件破坏引起的冲击效应的精细数值分析模型，并进行近断层强震作用下斜拉桥倒塌全过程数值仿真分析；并开展近断层强震多维多点激励下斜拉桥倒塌破坏振动台试验，验证数值分析模型；基于精细数值仿真分析模型，探讨速度脉冲、地震动空间效应、多维地震动等因素对斜拉桥倒塌破坏模式的影响规律，进一步揭示强震作用下斜拉桥的失效机理和倒塌破坏模式，为斜拉桥的防地震倒塌设计提供基础理论。

斜拉桥通常是交通枢纽工程，一旦在地震中遭到破坏，将会造成巨大的经济损失。然而，具有强烈的速度脉冲的近断层地震动通常会对长周期的斜拉桥产生较大的破坏。本项目从近断层地震动特性及人工拟合方法、斜拉桥的地震响应规律、近断层作用下斜拉桥倒塌破坏机理等方面分析开展的研究工作。项目研究过程中，采用了理论推导、数值模拟及振动台试验等各种手段。本项目提出了能考虑脉冲速度特性的近断层地震动的合成技术；建立能够考虑构件破坏的精细数值分析模型，并进行近断层强震作用下斜拉桥倒塌破坏过程数值仿真分析；开展近断层强震多维多点激励下斜拉桥振动台试验，验证数值分析模型；基于精细数值仿真分析模型，探讨不同的近断层地震动特性对于斜拉桥倒塌破坏模式的影响规律，进一步揭示强震作用下斜拉桥的失效机理和倒塌破坏模式。本项目的研究成果为斜拉桥的防地震倒塌设计提供基础理论。