空间强震差动—水动力耦合激励下桥梁致灾机制的混合试验研究

The damage mechanism of the large bridge structures subjected to strong seismic excitation is very complicated. Since the seismic test facility has limitation and the simulation technology are still not available, it is not possible to take into account the spatial seismic excitation and the dynamic fluid interaction effects in the experiment at the same time. This shortage causes that most of the formerly proposed analysis models, methods and theories for bridges cannot be verified through shaking table tests. In this project, it will focus on the large span bridges, on the reproduce and represent of the real seismic spatial excitation and fluid-structure dynamic interaction effect in the laboratory based on the underwater shaking table array facility. The spatial seismic field representation method will be conducted for the shaking table array test. The structure-fluid-shaking table dynamic interaction side effect will be eliminated through the development of multi-variable optimization control theory for the servo-hydraulic system; the hybrid testing framework will be constructed based on hybrid of experiment and simulation method, and the damage effect on the bridges subjecting strong ground motion will be reproduced, and the damage mechanism of bridges will be revealed. The mainly achievements of this project will includes, spatial seismic excitation field for underwater shaking table array, multi-variable feedforward/feedback LQG optimal control algorithm for uniaxial servo-hydraulic actuator or shaking table, the multi-variable H∞ optimal control theory for underwater shaking tables, the model parameter estimation and model update algorithm for substructures taking into account the nonlinear property of specimens and water vibration characteristics, the hybrid testing theory with applying dynamic boundary condition with shaking table and servo-hydraulic actuators, and the damage collapse mechanism of bridges subjecting spatial seismic excitation and dynamic fluid interaction effects. It will serve for the earthquake safety research of the large engineering structures, and exploration in depth of this topic. The results of this project are of great value both in theory and in practice.

大型桥梁结构在强震作用下的致灾效应十分复杂，目前已有的振动台试验设施尚无法同时考虑地震空间差动和水动力耦合这两种关键效应。这使得很多桥梁抗震分析模型、方法和理论暂时无法通过试验验证。本项目以大型桥梁为研究对象，依托水下地震模拟振动台台阵科研仪器，研究适用于水下振动台台阵试验的地震动场模拟模型，通过提出基于多参量优化的伺服作动系统控制理论，消除试件、水体非线性与台阵的动力相互作用影响，建立试验仿真相结合的水下振动台台阵混合试验平台，开展桥梁结构强震致灾效应的复现研究，揭示桥梁强震破坏机制。项目预期将建立：水下台阵地震动场输入模型，多参量反馈/前馈的LQG优化控制算法，考虑试件、水体非线性的水下模拟振动台多参量H∞优化控制理论，混合试验子结构参数辨识与模型更新算法，空间差动和水动力耦合下的桥梁致灾机制。研究成果将为我国大型工程抗震安全性研究和深入探索奠定基础，具有重大的理论意义和社会经济价值。

通过统计地震动（场）的时空特征，建立了非一致强地震动（场）特征的数学描述；对比人工合成和实际观测地震动（场）记录，验证了合成的多点、多维地震动（场）可以满足指定的地震风险，并且可考虑近断层方向性效应、Fling-step效应；识别水下振动台伺服动力系统关键组件的动力特性，基于“数字孪生”技术建立了虚拟振动台；考虑有水/无水，实测、分析了水下地震模拟振动台阵试验中动力特性受水体扰动影响，建立了多轴耦联的多自由度振动台解耦控制方法；研发并验证了智能控制算法和基于模型预估的自适应控制算法，建立了水下振动台系统的多参量优化控制算法；提出了协调相似率用于水—地震耦合试验中的水动力加载；提出了考虑土—结构、水—结构耦联的实时混合试验方法，并初步进行了有/无水体、有/无土体试验验证；研发了多振动台、伺服作动器的混合实验平台，特别针对施加复杂边界（适用于高层结构试验和桥梁SSI效应试验）的实时子结构稳定性判据、时滞补偿进行研究，提出了考虑数值子结构时间积分算法的多速率子结构稳定判定方法；进行了新型预制装配CFST摇摆桥墩的抗震韧性研究，并进行了摇摆桥梁体系的水下地震模拟振动台（无水、有水）试验等，揭示了地震—水体耦联对新型桥梁体系的致灾机制。预期本项目结题后，将继续结合水下地震模拟振动台阵开展实时混合试验研究，深入了解水中结构受多场动力灾变效应的破坏机理，服务于我国土木、水利、海洋重大工程建设。.本项目也为国家自然科学基金重大科研仪器研制专项“水下地震模拟振动台台阵研制”项目的顺利实施提供了技术支持，并为“十三·五”国家重大科技基础设施—“大型地震工程模拟研究设施”的论证、可行性研究和成功立项奠定了理论基础，积累了关键技术。