【作者】 王国庆；

【导师】 何沛祥；

【作者基本信息】 合肥工业大学 ， 桥梁与隧道工程， 2022， 硕士

【摘要】 矮塔斜拉桥是一种受力复杂、非线性行为较强的组合体系桥。因其跨越能力强,在我国被广泛使用。同时,我国又作为世界上地震多发国家之一。因此,迫切需要对地震作用下的矮塔斜拉桥展开研究。本文对一座在建预应力钢筋混凝土矮塔斜拉桥展开地震易损性分析,主要研究内容如下:(1)总结桥梁地震易损性分析方法和国内外研究现状,探讨易损性分析方法在矮塔斜拉桥应用中存在的不足,明确本文研究方法及内容。(2)基于Opensees有限元分析软件建立桥梁有限元模型,针对传统建模方法存在的缺点和不足,采用基于文件I/O功能的快速参数化建模方法建立主梁和主塔的有限元模型,并根据桥梁结构特点采用纤维单元模拟过渡墩和主墩力学行为。采用MIDAS/CIVIL有限元软件对Opensees所建模型的动力分析结果进行验证,确保用于计算的有限元模型准确可靠。(3)以El-Centro波为例,采用非线性时程分析方法计算桥梁在地震作用下的响应,探讨在不同PGA下,不同部位的混凝土峰值应力、应变和普通钢筋力学参数的改变对支座位移、过渡墩墩底曲率和主墩墩底曲率的影响。(4)采用试验设计方法并结合前述的研究成果,选取对地震响应影响较大的材料参数组建桥梁地震动样本组,针对传统易损性分析方法的不足,引入神经网络代理模型计算并获取支座、过渡墩和主墩易损性曲线,并与传统有限元方法所得易损性曲线进行比较,对构件抗震性能展开评估。(5)考虑到系统易损性中各构件之间存在的相关性,引入Copula函数求解构件间的联合失效概率,基于AIC准则对Copula函数进行优选,建立基于Copula函数的系统易损性曲线并将其与一阶界限法进行比较,结果表明该方法能够在考虑构件相关性的情况下获取精准的系统失效概率值,是一种可靠的易损性分析方法。更多还原

【Abstract】 The extradosed cable-stayed bridge,which is a combined system bridge with complex mechanical properties and strong nonlinear behavior,is widely used because of its strong span capacity.Meanwhile,China is one of the earthquake-prone countries in the world.Therefore,it is urgent to research the extradosed cable-stayed bridge under earthquakes.In this thesis,a reinforced concrete extradosed cable-stayed bridge was used for studying its seismic fragility.The main contents are as follows:(1)The methods on seismic fragility of bridges and research status are summarized.Existing shortcomings of seismic fragility methods in the application of the extradosed cable-stayed bridge are discussed.The research methods and contents of this thesis are proposed.(2)A finite element model based on Opensees is established.Considering the flaws of traditional modeling methods,the file I/O function and the fast parametric modeling method are introduced to establish the finite element models of main beams and main towers.Based on the stress characteristics of the bridge,fiber elements are used to simulate the mechanical properties of transition piers and main piers.MIDAS/CIVIL finite element software is used to verify the dynamic analysis results of the model built by Opensees to ensure that the Opensees model is accurate and reliable.(3)El-Centro wave and nonlinear time-course analysis methods are used to calculate the response of the bridge under earthquakes.The effects of the peak stress and strain of concrete in different parts and the mechanical parameters of ordinary reinforcement on the bearing displacement,the curvature of transition pier bottom and main pier bottom under different PGA are investigated.(4)By using the experimental design method and combined with the above research results,the material parameters that have a great impact on the seismic response are selected to form the bridge ground motion sample group.In view of the shortcomings of traditional seismic fragility analysis methods,neural network metamodel is introduced to calculate and obtain the fragility curves of bearing,transition pier and main pier,which are compared with the fragility curves obtained by the traditional finite element method to evaluate the seismic performance of components.(5)Considering the correlation between the components in the system fragility,the Copula function is introduced to obtain the joint failure probability between the components,and the AIC criterion is used to select the optimal Copula function.Then system fragility curves based on the Copula function are completed which are compared with the first-order boundary method.The results show that the proposed method can obtain accurate system failure probability while considering the correlation of components,and it is a reliable fragility analysis method.更多还原