车辆作用下具有裂缝的中小跨径梁式桥的自振特性分析

发布时间：2018-01-16 16:02

本文关键词：车辆作用下具有裂缝的中小跨径梁式桥的自振特性分析　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：梁式桥的损伤不可避免的会导致其刚度发生变化,从而导致其自振频率和振型等动力特性发生变化,这便为基于动力特性的梁式桥的损伤识别提供了理论基础。由于桥梁结构的动力荷载试验具有测试时间短,客观性强,无需封闭交通,能够发现隐蔽部位的病害等优点,因此基于动力特性的桥梁结构损伤识别备受人们的青睐。然而动力特性的准确性直接决定了损伤识别结果的优劣。有关研究资料表明,动力特性的准确性并不是由测试方法本身所决定的,桥梁上的通行车辆和环境温度改变都会导致动力特性的变异,有时这种变异会完全掩盖由结构损伤引起的动力特性变异。因此如何剔除外界因素引起的动力特性变异或在损伤识别时考虑由外界因素引起的动力特性变异是十分必要的。对于中小跨径梁式桥而言,为了在动力荷载试验过程中测得信噪比相对较高的动力时程响应,往往采用车辆对桥梁进行激励。一般来说,车辆激励可分为采用试验车辆对桥梁进行冲击(跳车试验)以及采用通行车辆对桥梁进行随机激励。无论是何种激励,测试到的动力特性其实是以桥梁振动为重要振动形式的车-桥耦合系统的动力特性,动力特性中均包含了车辆的影响。裂缝是梁式桥最为常见的病害之一,裂缝是如何影响梁式桥的动力特性的,至今还没有形成统一的认识。裂缝中小跨径梁式桥同样也采用车辆进行激振,这时测试到的桥梁动力特性其实是车辆和裂缝耦合影响下的动力特性。建立车辆作用下、车辆和裂缝耦合作用下梁式桥的动力特性计算方法,剖析车辆作用以及车辆和裂缝耦合作用对其动力特性的影响机理和影响规律,是使得测试到的动力特性能够应用到桥梁损伤识别中的技术保障。为了解决以上问题,本文结合国家自然科学基金项目“考虑车辆和温度耦合作用的中小跨径梁式桥固有频率分析方法研究”和吉林大学种子基金项目“车辆作用下中小跨径梁式桥固有频率分析方法研究”,开展了车辆作用下具有裂缝的中小跨径梁式桥的动力特性分析方法研究,具体研究内容如下:1、依据车辆振动方程和梁体振型函数,基于中支点处变形连续和力的平衡条件,采用数值组装方法建立了多个车辆作用下等截面连续梁的动力特性特征方程。采用传递矩阵方法来表征变截面梁的振型函数,根据车辆振动方程和边界条件得到了多个车辆作用下变截面简支梁的动力特性特征方程。依据建立的动力特性特征方程计算了多个车辆作用工况下等截面连续梁和变截面简支梁的动力特性,并讨论了车辆参数对其动力特性的影响。2、采用无质量扭转弹簧来模拟裂缝,并形成了裂缝位置处梁体振型函数待定系数的传递关系。依据车辆的振动方程以及采用传递矩阵方法表征的振型函数,建立了采用待定系数表示的车辆和裂缝作用下简支梁桥的耦合体系振动方程,并给出了其求解方法。根据建立的理论计算模型,计算了多种车辆作用、裂缝作用工况下的简支梁的动力特性,并讨论了车辆参数和裂缝参数对其动力特性的影响。3、采用单自由度弹簧-质量系统来模拟车辆,首先构建了任意数量车辆作用下具有任意裂缝数量的连续梁的等效计算模型。通过对已有方法的改进,采用一组基函数来表征梁体的振型函数,得到了单跨内梁体振型函数的递推关系。依据单跨内梁体振型函数和中支点处变形连续和力的平衡条件,以及弹簧-质量系统振动方程,形成了任意数量车辆作用下具有任意裂缝数量的连续梁的动力特性计算方法。同样讨论了车辆参数和裂缝参数对其动力特性的影响。
[Abstract]:Liang Shiqiao's injury inevitably lead to the rigidity changes, leading to its natural frequency and modal shape change, which provides a theoretical basis for the damage identification of girder bridge based on dynamic characteristics. Due to the dynamic load test of bridge structure with short test time, strong objectivity, without closed to traffic to discover the advantages, the hidden parts of the disease, so the damage identification of bridge structure based on the dynamic characteristics of the popular with people of all ages. However the accuracy of dynamic characteristics directly determine the damage identification result. Relevant research data show that the dynamic characteristics of the accuracy is not determined by this test method itself, vehicles and the environment temperature of bridge the change will lead to the variation of dynamic characteristics, sometimes this variant will completely obscured by the structural damage caused by the variation of dynamic characteristics. So how to tick In addition to the dynamic characteristics or variation of external factors caused by considering the variation of dynamic characteristics caused by external factors in the damage identification is necessary. For the small and medium span bridge, in the dynamic load test in the process of the measured signal-to-noise ratio is relatively high dynamic response, often using the vehicle on the bridge for a general incentive. Motivation can be divided into the vehicle, the vehicle test impact on bridge (jumping test) and the use of vehicles of random excitation on the bridge. No matter what kind of motivation is to test dynamic characteristics of dynamic characteristics of the bridge vibration is an important form of vibration of vehicle bridge coupling system dynamic characteristics, which include the effect of vehicle. Crack is one of the most common diseases of beam bridge, crack is how to affect the dynamic characteristics of the bridge, has not yet formed a unified understanding. Small and medium span crack Diameter of beam bridge also uses the vehicle vibration, the bridge dynamic characteristics when it is tested to the dynamic characteristics of vehicle and crack under coupling. Vehicles built under the calculation method of dynamic characteristics of beam bridge and vehicle cracks under coupling effect of vehicles and vehicles and to analyze crack coupling effects on its dynamic characteristics the mechanism and effect of dynamic characteristics, is to make the test can be applied to guarantee the bridge damage identification. In order to solve the above problems, combined with the National Natural Science Fund Project "consider the vehicle and temperature coupling effect of small and medium span beam bridge natural frequency analysis method research and the Jilin University seed fund project" under the action of small vehicles span bridge natural frequency analysis method research, carry out dynamic medium span girder bridges with cracks under the action of the vehicle. Study on the method of analysis, the specific contents are as follows: 1, according to the vehicle vibration equation of beam and Tizhen type function, equilibrium conditions and continuous force in support of deformation based on the numerical method of assembly dynamics characteristics of continuous beam multiple vehicles for sectional process. Using the mode function to characterize the variable cross section beam the transfer matrix method, according to the vehicle vibration equation and boundary condition, dynamic characteristics of the characteristic equation of variable section beam under several vehicles. Based on the dynamic characteristics of the characteristic equation established multiple vehicle working conditions of uniform section continuous beam of variable cross section beam and calculated the dynamic characteristics, and discusses the influence of parameters on the dynamic characteristics of vehicle.2, the quality of the torsion spring to simulate cracks, and the formation of cracks at the position of the undetermined coefficient transfer function. On the basis of Tizhen beam type vibration of vehicle The process and the modal function of transfer matrix method for the characterization of the established system coupling vibration equation of beam bridge using undetermined coefficient and crack under the action of the vehicle, and gives the solving method. Calculation model is established according to the theory, a variety of vehicles is calculated, the dynamic characteristics of beam crack condition, and discuss the vehicle parameters and fracture parameters on the dynamic characteristics of.3, the single degree of freedom spring mass system to simulate vehicle, first constructed a calculation model with arbitrary number of cracks of arbitrary number of vehicles under the action of the equivalent continuous beam. Through the improvement of the existing methods, the modal function using a set of basis functions to characterize the beam the beam has been Tizhen type function of single span recursive relationship. According to the balance conditions and capacity of single span continuous beam Tizhen type function and support deformation, and spring - mass The dynamic equation of continuous beam with arbitrary number of cracks is formed when any number of vehicles is acted on. The influence of vehicle parameters and crack parameters on its dynamic characteristics is also discussed.

【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U441.3

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