既有预应力混凝土梁桥结构损伤评估研究

发布时间：2018-09-07 11:39

【摘要】：工程中,既有桥梁结构的损伤评估与加固分析多采用试验测试或基准有限元建模分析,存在局限性。尤其是建立有限元模型时,要对真实结构做各种假设,使得有限元模型与实际结构存在误差,计算值和试验测量值不能很好的一致,这给桥梁的状态评估、剩余寿命的预测增加了困难。故如何修正有限元模型,改善既有结构的建模精度,一直是研究的热点。目前比较公认的和可行的方法是利用计算机技术把实验测试结果与计算机仿真集成进行有限元修正。基于此,本文尝试建立ANSYS平台的结构初始有限元模型,结合实桥结构试验测试结果,对结构参数进行灵敏度分析得到主要修正参数,借助ANSYS优化模块中一阶搜索优化理论的结构参数估计技术,对结构的初始有限元模型进行策略性修正。研究比较了不同有限元修正技术的可行性及有效性,并将修正后的有限元模型作为基准模型应用于既有预应力实桥的承载力评估与加固分析。结果表明,文述方法可以用于既有预应力桥梁结构的健康状态评估。主要工作如下:1.以某运营多年的实桥为工程依托,运用载荷试验方法,对结构主梁和主要的连系构件进行了全面的检测,通过静载试验、动载试验等手段获取桥梁的基本静动力特性。根据现场初步损伤诊断结果分析得到的直接损伤信息,为用ANSYS平台建立损伤有限元数值模型提供了数据依据。2.依据实桥检测结果,建立其参数化有限元模型,尝试采用具有针对性的修正策略借助一阶搜索优化的算法,对试验段构件分别进行了基于静力测试、动力测试以及联合应用静动力测试数据的有限元模型修正。比较了不同方法的模型修正效率和效果,介绍了优化方法的选择,并指出有限元模型修正是一个针对性很强的技术,几乎没有一种普适的算法进行修正,因而对于不同类型的工程结构应发展出相应合适的修正方法,尽可能获得相对准确的修正模型。3.考虑到既有大跨径预应力混凝土桥梁的力学特性比一般结构受更多因素的影响,修正参数的选取人工干预较大,使得传统有限元修正结果的稳定性和适用性较差,本文利用蚁群优化算法在解决复杂的、不确定性及非线性等问题的优势,尝试引入基于蚁群算法的有限元模型修正。结果表明,该模型是有效的,从而为工程中的大型结构的有限元模型修正提供了新的思路。4.依托既有预应力混凝土实桥,将修正后的有限元模型作为基准模型,对其承载力进行状态评估,表明修正后的有限元模型能够比较准确的反映桥梁的实际受力状态,可以用于既有预应力混凝土桥梁结构的损伤评估与识别。在此基础上,对结构损伤严重的部位提出了加固方案,建立了加固后的有限元模型,比较加固前后的承载力,验证了加固方法的有效性。
[Abstract]:In the engineering, the damage assessment and reinforcement analysis of existing bridge structures are usually carried out by means of test or benchmark finite element modeling analysis, which has some limitations. Especially when establishing the finite element model, we should make various assumptions about the real structure, which make the finite element model and the actual structure have errors, the calculated value and the experimental measurement value can not be in good agreement, which gives the bridge state evaluation. Prediction of residual life increases difficulties. Therefore, how to modify the finite element model and improve the modeling accuracy of existing structures has been a hot topic. At present, the widely accepted and feasible method is to use computer technology to integrate the experimental results with computer simulation to modify the finite element method. Based on this, this paper attempts to establish the initial finite element model of the structure of ANSYS platform. Combined with the test results of the real bridge structure, the main modified parameters are obtained by the sensitivity analysis of the structural parameters. With the help of the first-order search optimization theory in ANSYS optimization module, the structure parameter estimation technique is used to modify the initial finite element model of the structure strategically. The feasibility and effectiveness of different finite element modification techniques are studied and compared, and the modified finite element model is used as the benchmark model to evaluate the bearing capacity and strengthen the existing prestressed bridge. The results show that the method can be used to evaluate the health status of existing prestressed bridge structures. The main work is as follows: 1. Based on a real bridge which has been in operation for many years, the basic static and dynamic characteristics of the bridge are obtained by means of static load test and dynamic load test. According to the direct damage information obtained from the analysis of the field preliminary damage diagnosis results, this paper provides a data basis for the establishment of the damage finite element numerical model based on the ANSYS platform. Based on the test results of real bridge, the parametric finite element model is established, and the static test of the components of the test section is carried out based on the first order search optimization algorithm. Dynamic test and finite element model modification for combined application of static and dynamic test data. This paper compares the efficiency and effect of model modification with different methods, introduces the selection of optimization methods, and points out that the finite element model modification is a highly targeted technique, and almost no universal algorithm is used to modify it. Therefore, it is necessary to develop appropriate correction methods for different types of engineering structures, and to obtain as far as possible a relatively accurate correction model .3. Considering that the mechanical properties of existing long-span prestressed concrete bridges are affected by more factors than those of general structures, the selection of modification parameters is more important, which makes the stability and applicability of the traditional finite element correction worse. Based on the advantages of ant colony optimization in solving complex, uncertain and nonlinear problems, this paper attempts to introduce a finite element model modification based on ant colony algorithm. The results show that the model is effective and provides a new idea for the finite element model modification of large structures in engineering. Based on the existing prestressed concrete bridge, the modified finite element model is used as the benchmark model to evaluate the bearing capacity of the bridge, which shows that the modified finite element model can accurately reflect the actual stress state of the bridge. It can be used for damage assessment and identification of existing prestressed concrete bridge structures. On this basis, the reinforcement scheme is proposed for the severely damaged parts of the structure, and the finite element model after strengthening is established. The bearing capacity before and after reinforcement is compared, and the effectiveness of the reinforcement method is verified.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441;U448.35

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