近场脉冲型地震动作用下自复位桥梁结构的抗震性能研究

Bridge structures may suffer the large plastic deformation after near-field ground motions with pulse-type that result in extensive structural damage along with the large residual deformations. The large residual displacements substantially reduce the anti-seismic capacity of bridge structures during the aftershock and increase the difficulty and cost of structural repairs after the earthquake. In order to meet the functional requirement of bridge structures after the earthquake, a resilient structure system was proposed. This project intends to develop a novel self-centering energy dissipation brace with shape memory alloy cables. The hysteretic behavior and the failure mechanism of the brace are studied by the quasi-static test. Based on Bouc-Wen model, the restoring force model of the self-centering energy dissipation brace is established. The design concept for the bridge structures with the self-centering energy dissipation brace as a resilient structure was developed based on the stable energy dissipation and excellent self-centering capacities. The design method of the design parameters of the self-centering energy dissipation brace for the bridge structure is also given. The seismic performance, failure mechanism and post-earthquake recovery capability of self-centering energy-dissipated bridge structures under near-field ground motion with pulse-type are then studied. The project will further extend the design concept of the structural fuse and the resilient structure and promote the development of the self-resetting energy-dissipated bridge structure design.

桥梁结构在近场脉冲型地震作用下可能会产生严重的塑性变形，致使结构在震后留有较大的残余变形。震后较大的残余变形会减小桥梁结构抵抗余震的能力，并且会增加震后结构加固维修的费用甚至需要将结构推倒重建。为满足桥梁结构在震后继续使用的要求，需发展能在震后快速自恢复的桥梁体系。本项目拟开发一种以形状记忆合金绞线为自复位材料的新型自复位耗能支撑；通过拟静力试验研究新型自复位耗能支撑的滞回性能及破坏机理；基于Bouc-Wen模型，建立自复位耗能支撑的恢复力模型；然后基于新型支撑稳定的耗能能力和良好的自恢复功能，提出通过附加自复位耗能支撑来实现桥梁结构震后自恢复的设计理念；同时给出附加于桥梁结构的自复位耗能支撑设计参数选取的设计方法；研究自复位耗能桥梁结构在近场脉冲型地震动作用下的抗震性能及震后恢复能力，并揭示结构地震破坏机理。本项目将扩展基于保险丝和自恢复的抗震设计理念，推动桥梁自恢复设计的发展。

提出了一种新型的自复位耗能支撑，详细阐述了该支撑的工作机理及自复位原理；探讨了组合碟簧预压力和防屈曲支撑耗能内芯承载力的选择方案及设计方法；通过拟静力试验研究了自复位防屈曲支撑的滞回特性及破坏机理。提出了将自复位耗能支撑附加到双柱式桥墩以提高桥梁整体结构抗震性能的设计理念；理论推导并获得了自复位耗能支撑与桥墩之间性能设计参数的定量关系；采用拟静力试验研究了自复位耗能支撑桥墩的滞回性能及破坏机理。基于Bouc-Wen模型建立了自复位耗能支撑桥墩结构的恢复力模型；采用试验数据验证了该模型模拟自复位耗能支撑桥墩的可行性和有效性；应用该模型分析了自复位耗能支撑桥梁结构在地震作用下的地震响应。采用试验数据验证了OpenSees中自复位耗能支撑桥墩数值模型的准确性；据此建立了附加自复位耗能支撑全桥数值模型，研究了全桥在地震作用下的抗震性能；并系统研究了支撑滞回性能参数对自复位耗能支撑桥梁结构抗震性能的影响规律，为自复位耗能支撑桥梁结构抗震设计提供建议参数。探讨了结构延性能力对自复位耗能支撑桥梁结构弹塑性反应谱的影响规律；系统研究了自复位耗能支撑桥梁结构强度折减系数在近场地震动作用下的发展规律；基于统计平均和回归分析方法，提出了可供自复位结构抗震设计使用的强度折减系数的计算公式。发展了自复位耗能支撑桥梁结构的直接基于位移的抗震设计方法，在该方法中提出了将最大位移和残余位移同时作为结构的性能目标，同时推导了自复位结构的等效阻尼比简化公式，并将该公式应用到设计方法中；探讨了P-Δ效应对结构目标位移的影响，并给出了考虑P-Δ效应的结构剪力及弯矩计算公式。