一新型自复位耗能支撑抗震性能研究

Buckling restrained braces (BRBs) are widely applied as structural fuses in bridge structures to protect the more important bridge components due to their excellent energy dissipation capacity. Due to the energy dissipating mechanism of the brace, bridge structure equipped with BRBs may suffer large residual displacement after a severe earthquake, which in turn can affect the functionality of the bridge. To overcome the shortcoming of BRB, self-centering device can be installed in the traditional BRB to form a self-centering BRB. Self-centering BRB can dissipate the seismic energy, and also can provide self-centering capability to the system, it is the recent research hotspot. This project intends to develop a novel self-centering energy dissipating device, in which the energy dissipating capability is provided by the rotational friction hinge damper and the self-centering mechanism is provided by the pre-stressed shape memory alloy (SMA) strands. The newly developed devices are proposed to be installed in the transverse and longitudinal directions of the bridge to simultaneously reduce the residual displacement and mitigate the pounding and unseating damages of bridge structures. The design procedures of the device will be proposed and quasi-static, dynamic shaking table tests and numerical simulations will be carried out to investigate the energy dissipation and self-centering performances of the device itself and the bridge structure equipped with the devices. The project will further extend the structural fuse based bridge design concept.

防屈曲支撑由于其较好的耗能性能常作为保险丝装置用来保护桥梁主体结构免受地震破坏。由于其耗能机理，防屈曲支撑会导致桥梁结构较大的残余变形，影响桥梁结构的使用功能。为减小残余变形，自复位装置可安装于传统防屈曲支撑中，构成了所谓的自复位防屈曲支撑。自复位防屈曲支撑在耗能的同时还能提供自恢复能力，是近年来的研究热点。本项目拟开发一种新型的自复位耗能支撑，由转动摩擦阻尼器提供耗能能力，而预张拉的形状记忆合金提供自复位功能。该支撑将同时安装于桥梁结构的横向与纵向，在减小震后残余位移的同时减轻桥梁结构的碰撞及落梁可能。项目将提出该新型自复位支撑的设计方法，对开发的新型支撑及安装有该支撑的桥梁结构（桥墩及全桥结构）进行拟静力试验、动力振动台试验和数值模拟。研究支撑的滞回性能和自复位能力以及桥梁结构的损伤破坏过程及破坏机理。项目将拓展基于保险丝的抗震设计理念，推动桥梁抗震设计理论的发展。

传统耗能支撑（例如防屈曲支撑）能够有效地耗散地震能量，从而起到保护工程结构的目的。但是由于其耗能机理，附加传统支撑的工程结构在大震后可能存在较大的残余位移。众所周知，过大的残余位移会使结构修复困难甚至需要推倒重建。为了减少强震作用下附加传统耗能支撑结构的残余位移，国内外学者们提出了自复位耗能支撑的概念。此类支撑不仅能提供稳定的耗能能力还能减小结构的残余位移，从而保障结构震后的功能可恢复性。但现有的自复位耗能支撑仍存在一定问题，例如有的自复位耗能支撑构造较复杂、价格也比较昂贵，不易应用于实际工程。本项目研发了一种新型自复位耗能支撑，并将其应用于双柱式桥墩的抗震性能提升中。项目采用理论分析、数值模拟及试验研究相结合的方法对该新型自复位耗能支撑及带有该支撑的双柱式桥墩的抗震性能进行了系统研究。主要研究内容包含：（1）提出一种新型自复位耗能支撑，并对其自复位及耗能性能进行系统的理论分析、试验研究与数值模拟，深入揭示其工作机理；（2）将该支撑应用于双柱式桥墩，通过动力振动台试验及拟静力数值模拟揭示支撑-双柱式桥墩体系的协同工作机理及桥梁结构的损伤破坏过程及破坏机理；（3）建立支撑-全桥数值模型，研究有无支撑的双柱式桥梁结构的非线性动力行为。研究表明该自复位耗能支撑构造简单，工作机理明确，能够有效地提高双柱式桥梁结构的抗震性能。项目对拓展基于保险丝理念的桥梁抗震设计及推动桥梁抗震设计理论的发展具有重要的理论意义和工程价值。