三维隔震桥梁近断层强震反应机理及抗震设计方法

Prominent vertical component of seismic ground motions was found from strong motion observation and field investigation in near-fault regions during several intense earthquakes, but present horizontal isolation technology cann't effectively isolate vertical seismic motions, mitigating seimsic damage of bridges under strong vertical or three-dimensional seismic motion is an important problem to be solved in future. Theory and application of three-dimenisonal isolation technology for bridges is investigated in this proposal, theory analysis, near-fault seimsic response and design method of three-dimensionally isolated bridges are studied through theoretical analysis, numerical simulation and dynamic experiment. Firstly, three-dimensional islation principle and suitable condtion of bridge structure; and then, mechanical model is established base on the proposed three-dimensional isolation bearing by the proposer of this program. Finite element model is founded, making use of the three-dimensional isolation bearing as bridge bearing, near-fault seimic behavior, isolation effectiveness and its influential factors are investigated by numerical simulation and dynamic experiment. then, scaled three-dimensionally isolated bridge structure is manufactured, horizontal and vertical isolation effectiveness of three-dimensionally isolated bridge are verified by earthquake simulation shaking table tests. At last, seismic design method of three-dimensionally isolated bridge structures is proposed and a design example is presented. Research achivements of this proposal is benificial to improve multi-dimensional seimsic security of bridge structures, expand application areas of three-dimensional technology and strengthen base isolation technology, with important scientific value and practical significance.

针对近断层地震中显著的竖向地震动特征及水平减隔震技术不能有效隔离竖向地震动等问题，如何减轻桥梁结构在近断层强三维地震作用下的工程震害已成为亟待解决的课题。本项目以桥梁结构三维隔震技术理论和应用为研究目标，通过理论分析、数值仿真和动力试验等方法开展三维隔震桥梁近断层地震反应及抗震设计方法研究。首先，理论分析桥梁结构三维隔震原理及其适用条件；其次，建立已提出的三维隔震装置力学模型，采用已提出的三维隔震装置作为支座建立三维隔震桥梁有限元模型，通过数值仿真研究三维隔震桥梁在近断层三维地震作用下的动力反应及其主要影响因素；然后，设计制作一座三维隔震桥梁缩尺模型结构，通过地震模拟振动台试验验证三维隔震桥梁的水平和竖向隔震效果；最后，提出三维隔震桥梁结构体系的抗震设计方法并给出设计实例。本项目的开展对于提高桥梁结构多维地震安全性、拓展三维隔震技术应用范围、完善减隔震技术理论具有重要的科学价值和现实意义。

上世纪末至今，随着地震动监测台网的规模化、网络化建设，强烈地震发生时越来越多地捕捉到了地面及工程结构上的振动记录，对工程地震学和结构抗震的发展具有重要意义。从多次强烈地震中已观测到比较显著的竖向地震动，而目前国内外广泛发展、研究和工程应用的建筑及桥梁基础隔震技术，都是水平隔震技术，基本不具有竖向隔震的作用，有时甚至会对竖向抗震不利。如何减轻桥梁结构在近断层强三维地震作用下的结构震动已成为亟待解决的重要课题。本项目以桥梁结构三维隔震技术应用基础理论和方法为研究目标，通过理论分析、数值模拟和模型试验等方法开展三维隔震桥梁近断层地震反应分析和抗震设计方法研究。重点开展了以下工作：①分析了桥梁结构三维隔震基本原理及其适用条件；②建立以提出三维隔震支座的力学模型和三维隔震桥梁数值仿真分析模型，数值分析三维隔震桥梁的水平和竖向隔震效果；③通过振动台试验验证三维隔震桥梁的水平和竖向隔震效果；④给出三维隔震桥梁的简化抗震设计方法实例。通过本项目研究，已完成预期目标，获得主要研究结果如下：根据水平隔震和竖向隔震的基本原理，确定了三维隔震桥梁结构体系的适用条件；建立了已提出的三维隔震装置的力学性能及计算方法，并通过拟静力试验验证了所提出三维隔震支座的力学性能；研究了低屈服点软钢菱形钢板阻尼器的力学性能，结果表明，设置水平放置菱形软钢阻尼器的三维隔震支座的竖向耗能能力明显增强，同时对竖向隔震性能改变并不大；通过地震模拟振动台试验验证了所提出三维隔震支座在连续桥梁中应用的水平和竖向隔震效果，振动台试验研究结果表明三维隔震桥梁的水平加速度及墩底弯矩隔震效果达到50%-80%左右，跨中竖向振动加速度和跨中弯矩隔震效果达到30%左右；建立了三维隔震桥梁简化设计方法。在本项目的支持下，发表相关学术论文10篇，其中SCI检索论文3篇，EI检索论文8篇；申请国家发明专利2项；协助培养博士生1人，培养硕士生1人；参加国内外学术交流4次；获得北京市公路科学科学技术奖三等奖1项。