【作者】 蓝章礼；

【导师】 杨小帆；

【作者基本信息】 重庆大学 ， 计算机软件与理论， 2008， 博士

【摘要】 桥梁是交通系统中的关键环节,但是,本应有较长生命周期的桥梁却在使用中面临着一系列危机。为了防止灾难性的事故发生,怎样对广泛使用中的桥梁进行监测已成为了一个重要的课题。为了尽早识别和定位桥梁上的潜在损伤,有必要对重要桥梁进行长期的健康监测和定期评估。然而,在上述工作开展前,首先应该可靠而准确的获得桥梁相关数据。本文重点对桥梁挠度数据的准确获取开展了研究,同时也对裂纹检测和桥梁健康模型识别进行了简要讨论。论文首先介绍了广义结构元和扩展形态学滤波,在此基础上,设计了4套挠度测量系统,简要介绍如下:(1)利用张力线作为静止参考线,采用视频采集和图像处理与识别的方法提出了非接触式张力线桥梁挠度测量系统,对该系统的组成、结构和测量原理进行了阐述,分析了系统可能产生的误差原因,并提出了相应的应对策略。精度实验和对比实验表明,该系统能够可靠获取高精度的桥梁挠度数据。目前,该系统已在一座实际的箱梁桥得到了应用。(2)提出了自适应全天候自标定测量系统,该系统能够同时测量桥梁的挠度和位移数据,其最显著的特点是能够自动完成比例标定。(3)针对桥梁挠度测量中快速重现桥梁连续挠度线形的需要,利用倾角传感器和位移传感模块,设计了连续挠度快速测量和重现系统,就系统的组成,硬件设计、软件和算法设计进行了阐述;(4)利用激光准直发射器和视频设备,实现了激光投射式桥梁挠度/位移测量系统。本文也研究了桥梁裂纹检测与损伤识别,主要做了以下工作。(1)提出了基于桥梁表面图像的裂纹识别与重建算法,对裂纹图像预处理、裂纹提取、存储和裂纹图像重建进行了阐述。(2)根据主元分析方法的原理,论文提出了基于主元分析的桥梁健康模型识别,探讨了桥梁测量数据的收集和模型建立的有关问题。此外,由于本文提出的测量方法需要,提出了广义结构元与扩展形态学滤波,就相关的定义、性质和应用进行了阐述。概括而言,本文研究和设计了4套新型挠度/位移测量系统,提出了桥梁裂纹检测和损伤识别的方法。更多还原

【Abstract】 Bridges are key elements in the transportation system, but aging bridges which are normally designed to have long life span are facing a severe crisis. It is an important issue how to monitor these widely used bridges in order to prevent potential catastrophic events.Continuous health monitoring or regular condition assessment of important bridges is necessary so that early identification and localization of any potential damage can be made. Before this work can be done, however, the bridge data must be acquired reliably and precisely. This thesis is focused mainly on the precise acquisition of bridge deflections, followed by a brief discussion of the crack detection and identification of a bridge.In this thesis, we first introduce the theory of the generalized structural element as well as that of the extended morphological filtering. On this basis, four deflection-measuring systems are designed, which are outlined below.(1) A non-contact weighted-stretched-wire system is developed. The principle, organization and structure of the system are discussed. Using a stretched wire as the stationary reference line, this system employs the video capturing, digital image processing and recognition techniques, simultaneously. Some possible sources of the measurement error produced by the system are analyzed, and the corresponding strategies are proposed. Through a series of laboratory experiments concerning the precision achievable by the system as well as the coherence between the measured values obtained by our system and by a deflection gauge, it is shown that the system can acquire the deflections in a bridge reliably and with a high precision. The proposed system has been applied to a real-life box-girder bridge.(2) An adaptive, all-weather self-calibration system is advised, which can monitor and detect both the displacements and the deflections in a bridge, simultaneously. One remarkable advantage of this system is that the calibration process is automated.(3) A system is designed for bridge alignment. The system configuration and hardware are described, followed by a description of the alignment algorithm as well as the relevant filtering algorithms used. In this system, the deflection values are acquired rapidly with the aid of tiltmeter and displacement sensing module.(4) A bridge (deflection, displacement)-measuring system is realized based on the laser alignment radiation and video equipment.The crack detection and damage identification of a bridge are also studied in this thesis, which is summarized as follows.(1) An algorithm is proposed for identifying and reconstructing the cracks in a bridge from a set of images of the bridge surface, which is accompanied with a detailed description of the methods for crack image preprocessing, crack extraction, storage and crack image reconstruction.(2) According to the principle of PCA (Principle Component Analysis), a PCA based bridge health model identification method is presented. Some issues related to the collection of the measured data and the establishment of model are also discussed.In summary, this thesis addresses the design of four novel systems for the precise acquisition of bridge deflections and/or displacements. New methods for the crack detection and damage identification of a bridge are also proposed.更多还原