【作者】 王宁波；

【导师】 任伟新；

【作者基本信息】 中南大学 ， 土木工程， 2013， 博士

【摘要】 由于重载车辆的大量推出以及超载现象的普遍存在,使得近年来因车辆荷载导致的桥梁安全事故屡屡发生。对高速车辆荷载的动态称重问题一直以来倍受关注,它在治理车辆超载,公路、桥梁等基础设施管养与健康安全评估等方面都具有非常重要的意义。本文主要针对一种较新的动态称重方法：非路面式桥梁动态称重(B-WIM)进行研究,以车辆过桥时产生的桥梁动力响应为对象,从影响线测定、车轴信息检测、车辆动态称重等角度研究B-WIM的基本理论,采用理论、数值模拟和实验的方法,研究车辆荷载的动态称重问题。论文的主要工作及结论包括：1.从时变性角度对车桥整体系统进行划分,通过分开建模、局部耦合的思路建立了汽车-桥梁耦合系统模型,编写Matlab计算程序对建立的汽车-桥梁耦合振动方程进行迭代求解,并根据迭代结果计算汽车过桥时桥梁动应变响应。数值计算结果表明,这样处理,提高了计算效率,有利于模拟车辆各车轴上桥、出桥的行为。2.提出了非路面式桥梁动态称重理论与优化算法,从桥梁影响线测定、车轴信息检测和车辆动态称重等角度推导了非路面式B-WIM算法,采用梯度法对初始B-WIM结果进行多参数局部优化研究,并结合车-桥耦合振动算例进行了验证。研究表明,以桥梁动应变响应为研究对象,采用影响线拟合的方法对车辆荷载进行动态称重研究,需要的系统参数少,可行性强,B-WIM系统以现存桥梁为“秤”,增加了敏感单元长度,对车载信息测试记录时间长,获取的数据信息量大,具有足够测试精度,较路面式动态称重方法优势明显。同时,局部优化研究能减小偶然因素产生的误差,尤其是减小速度识别误差所造成的影响,进一步提高结果精度,满足工程应用要求。3.提出了车轴信息识别的小波变换方法,结合小波变换时频局部化特性,将小波用于B-WIM中车轴信息识别环节,通过对模糊信号提取特定尺度下小波系数曲线,凸显与车轴对应的峰值点,有效解决联轴及短轴距车辆的车轴信息识别问题,并用数值模拟和实桥试验结果验证了所提出的方法。数值和试验结果表明,充分利用小波变换时频局部化特性,提取特定尺度下小波变换系数进行车轴信息识别,减小了干扰信号的影响,能够识别双联轴、三联轴等相对小轴距车轴信息,弥补了传统局部峰值法在平顶峰处连续判断等方面的不足,利于扩展B-WIM的适用范围。4.针对车辆激振频率存在不确定性,提出了车轴信息自动识别算法,旨在解决激振频率初始值确定和消除桥梁振动的干扰两个B-WIM中的关键问题。通过自动搜索寻找合适的初始激振频率,再以此迭代计算得到精确激振频率值和相应尺度系数,对该尺度系数下两动应变信号小波系数曲线进行互相关分析,取互相关函数最大值时两曲线状态作乘法运算,能消除小波系数曲线中的虚假峰值点,去除有色噪声的干扰,实现对车轴信息自动识别。整个过程仅需输入两不同断面测点信号就可实现对车轴信息的自动识别,不需要人为判断与取舍。5.研究了B-WIM对不同类型桥梁的适用性,并分析了桥梁尺寸、测点位置、测试噪音等因素对B-WIM的影响。结果表明：正交异性板桥、框架桥、T型梁桥、板桥都可较好的用作B-WIM研究,其适用范围涉及了我国高速公路及铁路桥梁大部分类型,具备广阔的应用前景。6.制定了B-WIM系统测试精度的评定标准、精度测试基本流程和精度等级统计计算方法。通过评定B-WIM系统,测试其能达到的精度等级水平,来衡量B-WIM系统是否具备实际工程应用价值,可为确定其用途提供重要参考依据。更多还原

【Abstract】 Since a large number of heavy vehicles have emerged and the phenomenon of overloading has become increasingly severe, the bridge safety incidents caused by traffic loads have happened frequently in recent years. The weigh-in-motion problem of high-speed vehicle loads that has been attracting much attention is of far-reaching significance in managing overloaded vehicles, administrating and maintaining the infrastructures such as highway and bridge, etc, as well as assessing the bridge health and safety conditions. This paper mainly focuses on a new weigh-in-motion method:non-pavement bridge weigh-in-metion (B-WIM) and takes the dynamic response of bridges generated by passing vehicles as the object and studies the fundamental theory of B-WIM from the point of influence line measurement, axle information detection and vehicle weighing-in-motion. By employing the methods of theory, numerical simulation and test, the weigh-in-motion problem of vehicle loads is investigated. Furthermore, the main work and some conclusions are drawn as follows:1. Based on the idea of modeling separately and coupling partly, the vehicle-bridge coupled system is modeled and the vehicle-bridge coupled vibration function is solved iteratively by using the Matlab program. According to the iterative results, the dynamic strain responses of the bridge are calculated when the vehicles passing which shows that this method can improve the efficiency of calculation and simulate each axle’s behavior of arriving and leaving the bridge effectively.2. The theory and optimized algorithm of the non-pavement bridge weigh-in-motion are proposed. The non-pavement B-WIM algorithm is derived from the determination of bridge influence line, detecting the information of axles and vehicle weigh-in-motion. The gradient method for multi-parameter partially optimized is introduced to investigate the initial B-WIM results. By compared with the results of the vehicle-bridge coupled vibration example, the results in this paper are verified. The investigation illustrates that less system parameters are needed and has a better feasibility by taking the bridge dynamic strain response as the object of research and using the influence line fitting method to research the weigh-in-motion of vehicle loads. The B-WIM system takes the existed bridge as a steelyard, increases the length of the sensitive elements, records a long time range of the vehicle information test, obtains more data and has enough precision and obvious advantages over the pavement weigh-in-motion. Meanwhile, the partially optimized research can reduce the deviation resulted from the accidental factors, especially reduce the influence caused by the deviation of velocity identification, improve the precision of the results and meet the requirements of engineering applications.3. The wavelet transform method for axle information identification is put forward. Taking into account the time-frequency localization characteristic of the wavelet transform, the wavelet is used for the axle information identification process of the B-WIM. By extracting wavelet coefficient curve under specified scale from fuzzy signal, the peak points corresponded to the axles are highlighted, especially to axles with short distance. The numerical and test results show that by using the time-frequency localization characteristic of the wavelet transform, extracting wavelet coefficients under specified scales to identify axle information, can reduce the influence of interference signals, identify axle information of double shaft, triple shaft and relatively small wheelbase, and remedy the deficiency of traditional partial peak-picking method about the continuous judgment at the flat peak. Expand the application range of B-WIM.4. Considering the uncertainty of vehicle exciting frequency, the automatic identification algorithm for axle information is proposed. Solving two crucial problems in B-WIM, determining the initial value of exciting frequency and eliminating the interference of bridge vibration is the objective. After automatically searching the suitable excitation initial frequency, the precise excitation frequency and corresponding scale coefficient are obtained through the iterative calculation. Taking the two wavelet coefficient curves of special scale for multiplication when the cross-correlation function reaches its maximum, which can filter the interference of colored noise and automatically identify the axle information. The whole procedure only requires signals of two measuring points on different sections rather than artificially judgments.5. The applicability of B-WIM upon different kinds of bridges and the influence of factors such as the size of bridges, the position of measuring points and measuring noise were analyzed. The results demonstrate that:bridges with orthotropic plate deck, frame bridges, T-beam bridges and slab bridges can be used for B-WIM researches. It can be used in most types of bridges in highway and railway in China and is considered to have broad application prospects.6. Precision assessment standard, procedures, and precision level statistical calculation method of B-WIM system test were developed. The actual engineering application of B-WIM system was evaluated by testing its precision level, and it can provide important reference for applications.更多还原