大跨斜拉桥阻尼器参数分析及地震易损性分析

发布时间：2018-07-20 19:38

【摘要】：大跨斜拉桥是交通生命线上重要的非规则桥梁,为了减轻其地震损害程度,工程中常在桥梁上设置减、隔震装置,达到延长结构周期,耗散地震能量,保护桥梁免受损伤的目的。桥梁结构的地震易损性反应结构在不同强度地面运动作用下,地震响应超过某一规定破坏状态的概率。地震易损性曲线是其最直观的表达形式,反应结构损伤和地震动的关系,是桥梁风险评估的一种很重要的手段,因此有必要对采用减隔震装置的斜拉桥进行易损性研究。本文以可克达拉大桥为例,对其进行阻尼器参数及地震易损性分析。主要内容如下:1.建立斜拉桥有限元模型进行动力特性分析,获得桥梁的基本周期和振型。在纵桥向设置粘滞阻尼器,通过非线性时程分析获得结构地震响应值,提取主梁跨中位移、塔底剪力、弯矩、阻尼器阻尼力,运用matlab进行曲面拟合,建立不同响应量的方程,构建效果评估函数,求出最佳阻尼系数C和阻尼指数ξ;横桥向在辅助墩、过渡墩、桥塔处设置钢阻尼器,提取关键截面的地震响应量,运用均值化方法对数据进行标准化处理,求出不同位置处钢阻尼器合理的屈服刚度。2.考虑结构的不确定性,选取钢筋弹性模量,钢筋的屈服强度,混凝土的弹性模量作为代表。运用拉丁超立方抽样(LHS)生成桥梁结构的样本,并和选定的地震波进行随机组合,生成“地震波-结构样本”集。建立不同样本的有限元模型,对地震波进行调幅,形成一系列小样本,对每一小样本进行非线性时程分析,提取关键构件的地震响应值。3.针对斜拉桥不同构件提出不同的损伤指标,运用能力需求比方法得到斜拉桥不同部位的易损性曲线。通过比较桥塔各截面损伤概率的大小,可以得到纵桥向和横桥向的最容易损伤截面。并对设置阻尼器和不设置阻尼器两种情况下各构件的易损性进行对比分析,最后运用可靠度理论建立斜拉桥系统的地震易损性曲线。
[Abstract]:Long-span cable-stayed bridge is an important non-regular bridge in traffic lifeline. In order to reduce its earthquake damage degree, in order to reduce the earthquake damage, it is often installed in the bridge with isolation device to prolong the structural cycle and dissipate seismic energy. The purpose of protecting bridges from damage. The seismic response of bridge structures under the action of ground motion of different strength exceeds the probability of a specified failure state. Seismic vulnerability curve is the most intuitionistic expression, and the relationship between damage and ground motion is a very important means of bridge risk assessment, so it is necessary to study the vulnerability of cable-stayed bridge with isolation device. In this paper, the damper parameters and seismic vulnerability of Cockdara Bridge are analyzed. The main content is as follows: 1. The finite element model of cable-stayed bridge is established to analyze the dynamic characteristics, and the basic period and mode of the bridge are obtained. A viscous damper is set up in the longitudinal bridge. The seismic response value of the structure is obtained by nonlinear time-history analysis. The mid-span displacement of the main beam, the shear force at the bottom of the tower, the bending moment and the damping force of the damper are extracted. The curved surface fitting is carried out by using matlab, and the equations of different response quantities are established. The optimal damping coefficient C and damping index 尉 are obtained by constructing the effect evaluation function, steel dampers are installed at auxiliary piers, transition piers and towers to extract the seismic response of key sections, and the data are standardized by means of the mean value method. The reasonable yield stiffness of steel dampers at different positions is obtained. Considering the uncertainty of the structure, the elastic modulus of steel bar, yield strength of steel bar and elastic modulus of concrete are selected as representatives. The Latin hypercube sampling (LHS) is used to generate the bridge structure samples and the random combination of the selected seismic waves to generate the "seismic wave-structure samples" set. The finite element model of different samples was established, and a series of small samples were formed by amplitude modulation of seismic waves. The nonlinear time history analysis of each small sample was carried out, and the seismic response value of key components was extracted. According to different components of cable-stayed bridge, different damage indexes are put forward, and the vulnerability curves of different parts of cable-stayed bridge are obtained by the method of capacity demand ratio. By comparing the damage probability of each section of the bridge tower, the most easily damaged section of the longitudinal bridge direction and the transverse bridge direction can be obtained. Finally, the seismic vulnerability curves of cable-stayed bridge system are established by using reliability theory.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U442.55;U448.27

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