设置BRB跨海斜拉桥新型减震约束体系及其地震反应性态研究

More cross-sea bridges have been designed recently in China, for the offshore areas in China are surrounded by the Pacific Earthquake belts and strong earthquakes had occurred in the Bohai Straits，the Qiongzhou Straits and the Taiwan Straits in history, more attention should been paid to the seismic safety of the cross-sea bridges. In order to improve the seismic performance, durability and maintenance performance of the cross-sea cable-stayed bridges an innovative seismic response mitigation system for the cross-sea cable-stayed bridges by combined working of BRBs and Lock-up devices is presented. For preventing from the corrosion of the marine atmospheric effects the BRBs are made of stainless steels, mainly using austenitic stainless steel 316 and sometimes using duplex stainless steel 2205. The design methods of the stainless steel BRBs are achieved by improving the analysis theory of the normal steel BRBs by introducing the low-cycle fatigue life of the stainless steels which is obtained from the tests using MTS. The seismic performance and the hysteretic constitutive model of the stainless steel BRBs are obtained by the cyclic loading test. The pseudo-dynamic testing will be carried out based on the SDOF model to test the cooperated working performance of the combined system of BRBs and Lock-up devices with each other, and the forces-displacements hysteretic relationship will be presented considering the effects of loading velocity and frequency. The seismic performance of a real cross-sea cable-stayed bridge with the seismic response mitigation system will be numerical simulated consider coupled effects of the pile-soil-water interaction and also be verified by the shaking table test.

我国跨海桥梁建设已取得长足进步，因近海处环太平洋地震带，历史上渤海海峡、琼州海峡和台湾海峡都有强震发生，跨海桥梁抗震安全重要。本项目拟提出塔梁间设置屈曲约束支撑（BRB）的跨海斜拉桥新型减震约束体系，主要以“Lock-up装置与BRB”串联方式实现，将有助于提升跨海桥梁的抗震、运营和耐久性能。鉴于海洋腐蚀环境，拟发展不锈钢材质BRB，不锈钢以奥氏体316为主，兼顾双相2205。设计则从不锈钢材料低周疲劳试验和改造普通钢材BRB分析理论入手，再基于不锈钢BRB试件拟静力试验确认其抗震性能和建立滞回本构。基于单自由度系统开展“Lock-up装置与BRB”串联体系拟动力试验，再适当修正提出不同加载速率及频率下串联体系的力位移关系。以某实际跨海斜拉桥为案例，建立精细化跨海斜拉桥-桩-土-海水耦合地震反应分析模型，以数值模拟研究新型减震约束体系跨海斜拉桥地震反应性态，并基于大型振动台阵试验验证。

我国跨海桥梁建设已取得长足进步，因近海处环太平洋地震带，历史上渤海海峡、琼州海峡和台湾海峡都有强震发生，跨海桥梁抗震安全重要。本项目拟提出塔梁间设置屈曲约束支撑(BRB）的跨海斜拉桥新型减震约束体系，将有助于提升跨海桥梁的抗震、运营和耐久性能。鉴于海洋腐蚀环境，拟发展不锈钢材质BRB，以奥氏体304为主，兼顾双相2205。项目在以下方面有所创新或有新的认识：. 1)不锈钢材料低周疲劳特性研究：对不锈钢材进行了大应变下低周疲劳试验（拉压应变幅值5%），分析了奥氏体和双相型不锈钢的滞回行为，确定了奥氏体S304和双相型S2205不锈钢的循环骨架参数，给出了不同应变幅值下的循环硬化及软化程度及描述参数；确定了不锈钢材料的应变-疲劳寿命方程；结合ABAQUS软件提出了不锈钢材料的应力-应变本构参数，上述研究为不锈钢材料在结构抗震中的应用提供了必备的基础性数据。. 2）不锈钢金属耗能减震BRB设计：设计了开孔一字型、联合奥氏体和双向不锈钢的双屈服点型和采用碟簧（环形弹簧）的自复位3类新型BRB耗能减震元件；提出了组合使用Lock-up和BRB，可满足结构正常使用状态和强震作用下的不同工作机制及耗能要求；提出具有负泊松比效应的金属耗能减震BRB创新形式。. 3）设置BRB跨海斜拉桥减震约束体系：提出了斜拉桥纵桥向设置BRB的减震约束创新体系。特别指出了目前常用的纵桥向墩梁间设置液体粘滞阻尼器，当考虑桩-土-海水耦合作用分析后，可能会较大地放大下塔柱的弯矩反应。上述研究为跨海斜拉桥结构抗震选型，还有更深刻地认知液体粘滞阻尼器的减震性能，提供了富有启发性的线索。