基于动态试验的桥梁快速诊断技术研究

发布时间：2018-07-04 09:48

本文选题：桥梁结构 + 安全性能　；参考：《中国民航大学》2015年硕士论文

【摘要】：目前已有的桥梁结构检测方法主要有静力荷载试验法和动力试验法。其中静载试验法需长时间中断交通、耗时耗力;已有的动力试验法多以获得桥梁结构的模态信息作为评价桥梁结构性能的依据,其理论方法尚不够成熟,且实测数据对结构损伤灵敏度较弱。拟静力荷载试验是介于静力荷载试验和动力荷载试验之间的一种试验方法。通过对实测应变或挠度影响线分析对桥梁结构承载能力进行评定。拟静力荷载试验由于其对试验方法及数据采集设备的精度要求较高,在我国一直未得到大范围的应用。本课题在河北省交通科学基金资助下,提出基于动态试验的桥梁快速诊断技术。动态试验包括动力模态试验和动力荷载荷载试验。动力模态试验通过采集桥梁结构在正常交通量和大地振动激励下的加速度信号,对实测数据作傅里叶变换,得到桥梁结构的频率、振型、阻尼比、刚度等。动力荷载试验通过在桥面施加指定路径的标准加载车车辆荷载,采集桥梁结构各测点的应变或挠度影响线。以两种试验获得的桥梁结构的力学响应为依据,修正桥梁结构的有限元模型。模型优化过程中采用合理的设计变量、状态变量和有效的目标函数。将相同荷载工况下桥梁结构有限元模型的计算值与实测值进行比对,借助大型有限元软件ANSYS中的优化模块,不断调整设计变量的取值,直至有限元计算值与实测值误差无限小,即认为桥梁结构有限元模型修正完成,此时有限元模型等效于实际桥梁结构力学模型。在修正好的室内桥梁结构有限元模型上施加满足加载效率的静力荷载,利用静力荷载试验法评价桥梁结构的理论,对桥梁结构性能作出评价,从而达到快速有效评价桥梁健康状况的目的。针对本课题提出的基于动态试验的桥梁快速诊断技术,本论文做了如下几方面的研究:1.针对桥梁结构可能出现的各种损伤,通过室内有限元仿真模拟,研究了桥梁结构出现横向连接损伤、梁底裂缝等损伤时,动态试验实测结果的变化。为实际桥梁检测工程提供了理论支持,为试验方案的合理选择提供了依据。2.研究了配筋率、弹性模量、截面惯性矩对应变或挠度影响线的影响规律及影响程度,为有限元模型修正过程中设计变量的合理选取提供理论依据。3.建立了基于动力模态参数和应变影响线的桥梁结构初始有限元模型校准技术中的目标函数,通过合理选择目标函数的表达式,保证结构模型优化的收敛性和有效性,为桥梁结构有限元模型优化提供了依据。4.将本课题所提出的桥梁快速检测方法应用于机场滑行道桥和公路桥实际检测工程。借助桥梁实际检测工程详细介绍了动力模态试验和动力荷载试验的数据采集、分析过程,以及模型优化、仿真静力加载、桥梁结构评价的全过程,验证了本论文所提出方法的可行性。
[Abstract]:At present, the existing methods of bridge structure testing mainly include static load test method and dynamic test method. Among them, the static load test method needs to interrupt traffic for a long time, which is time-consuming and labor-consuming. Most of the existing dynamic test methods take the modal information of bridge structure as the basis for evaluating the performance of bridge structure, and its theoretical method is not mature enough. The sensitivity of measured data to structural damage is weak. Pseudostatic load test is a test method between static load test and dynamic load test. The bearing capacity of bridge structure is evaluated by analyzing the influence line of measured strain or deflection. Quasi-static load test has not been widely used in China because of its high precision requirements for test methods and data acquisition equipment. In this paper, a bridge rapid diagnosis technique based on dynamic test is proposed, supported by Hebei Provincial Traffic Science Foundation. Dynamic test includes dynamic modal test and dynamic load test. By collecting the acceleration signals of the bridge structure under the excitation of normal traffic volume and earth vibration, the dynamic modal test carries out Fourier transform to the measured data, and obtains the frequency, mode shape, damping ratio, stiffness and so on of the bridge structure. By applying the standard loading vehicle load on the bridge deck, the strain or deflection influence lines of each measuring point of the bridge structure are collected. Based on the mechanical response of bridge structure obtained by two kinds of tests, the finite element model of bridge structure is modified. Reasonable design variables, state variables and effective objective functions are used in the process of model optimization. Comparing the calculated value with the measured value of the finite element model of the bridge structure under the same load condition, with the help of the optimization module in the large-scale finite element software ANSYS, the value of the design variable is adjusted continuously until the error between the finite element calculation value and the measured value is infinitesimally small. It is considered that the finite element model of bridge structure is modified, and the finite element model is equivalent to the actual bridge structural mechanics model. Applying static load to the modified finite element model of indoor bridge structure to satisfy the loading efficiency, the theory of static load test method is used to evaluate the performance of bridge structure. In order to quickly and effectively evaluate the health status of the bridge. Aiming at the bridge rapid diagnosis technology based on dynamic test, this paper has done the following research: 1: 1. In view of the possible damage of bridge structure, the change of the measured results of dynamic test is studied when the bridge structure is damaged by transverse connection damage and beam bottom crack by means of indoor finite element simulation. It provides theoretical support for the actual bridge detection project and provides the basis for the reasonable selection of the test scheme. The influence of reinforcement ratio, elastic modulus and moment of inertia of section on the influence line of strain or deflection is studied, which provides a theoretical basis for the reasonable selection of design variables in the process of modification of finite element model. The objective function of the initial finite element model calibration technique for bridge structures based on dynamic modal parameters and strain influence lines is established. The convergence and effectiveness of structural model optimization are ensured by selecting the expression of the objective function reasonably. It provides the basis for the optimization of finite element model of bridge structure. The proposed method is applied to the practical detection of taxiway bridge and highway bridge. The data acquisition and analysis process of dynamic modal test and dynamic load test, as well as the whole process of model optimization, simulation static loading and bridge structure evaluation are introduced in detail with the help of bridge actual testing project. The feasibility of the proposed method is verified.
【学位授予单位】：中国民航大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U446

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