【作者】 黄盛楠；

【导师】 叶列平；

【作者基本信息】 清华大学 ， 土木工程， 2008， 博士

【摘要】 随着交通事业的发展,桥梁健康监测已成为近年来的研究热点,损伤识别是桥梁健康监测过程中的关键环节。本文以钢筋混凝土简支梁和连续梁桥为研究对象,通过理论分析、数值模拟分析和试验分析,针对超载造成的损伤问题,研究其识别方法。论文的主要工作和研究成果如下:(1)针对加载对钢筋混凝土梁桥造成的损伤,对常用的动力指纹方法进行了总结及敏感性分析,提出了基于柔度矩阵的β指标和η指标的损伤定位识别方法,经数值试验验证了其识别能力。(2)针对损伤程度的识别问题,本文提出了改进直接刚度法和截面工作状态评估方法。基于数值试验,通过与已有的直接刚度法和有限元程序计算结果的比较,验证了本文提出的改进直接刚度法的准确性。完成了两个跨度7m的钢筋混凝土梁的试验,应用本文提出的基于改进直接刚度法的截面工作状态评估方法对其进行了损伤程度的评估。(3)针对超载造成的损伤问题,本文建立了模态力面积与荷载归一化指标之间的关系,提出了基于模态力和有限元仿真计算的历史最大荷载识别方法,并将该方法应用于两个跨度7m的钢筋混凝土试验梁,验证了其准确性。(4)基于上述研究成果,提出了钢筋混凝土梁桥的损伤识别流程。完成了一个18m长3跨钢筋混凝土连续梁桥的模型试验,通过4种加载工况和10个荷载步模拟了车行荷载和超载问题,测试了每个荷载步后结构的动力性能,将本文提出的损伤识别流程应用于模型桥的损伤分析。结果表明,本文提出的方法可以有效地对模型桥各荷载步的损伤位置和损伤程度进行识别。(5)针对动测不敏感部位(如振型位移为0的支座处),本文研制开发了CFRP预警传感器和预应力CFRP预警传感器。试验测试结果表明,CFRP预警传感器对钢筋混凝土梁的开裂和钢筋屈服等关键点具有预警能力,预应力CFRP传感器可以有效的降低电阻突变信号的应变值,提高了其在低应变区间的敏感度。更多还原

【Abstract】 With the development of the transportation, bridge health monitoring has become a hot research topic, in which damage identification is a key problem. In this dissertation, the damage identification of simple supported or continuous reinforced concrete (RC) girder bridges caused by overloading is studied through theoretical analysis, numerical simulation and experimental analysis. The main works and achievements are as follows:(1) The frequently used dynamic fingerprints are summarized and their sensitivities are analyzed for the damage identification of RC girder bridges.βindex andηindex based on flexibility matrix are proposed to detect damage position, and the feasibility of the proposed process is proved with numerical simulation.(2) To identify the damage degree, an improved direct stiffness determination (IDSD) method, together with a sectional service-state evaluation method, is proposed. The accuracy of proposed IDSD method is proved by the comparison with the results of existing direct stiffness determination method and finite element (FE) analysis. Two RC beams with a span of 7m are tested and their damage degrees are assessed with the proposed service-state evaluation method which is based on IDSD method.(3) For damage identification caused by overloading, the relationship between modal force area and Normalized Load Level index is established. The historical maximal load identification method is proposed which is based on the modal force and FE simulation. This method is successfully applied in two 7m RC beam experiments to assess the different load levels.(4) Based on the above works, the damage detection procedure of RC girder bridges is proposed. A continuous rigid frame concrete model bridge, which has 3 spans and a total length of 18m, is implemented in this work. Four load cases and ten different load steps are tested to simulate the vehicle load and different levels of overloading. After every load step, dynamic properties of the bridge are tested, and damage detection procedure is used to identify the damage of the model bridge. The results show that the proposed procedure in this dissertation is able to identify the damage position and damage degree effectively on every load step.(5) In order to detect the damages located at the position where the displacement mode is unsensitive, CFRP alarm sensors and prestressed CFRP alarm sensors are developed. Test results show that CFRP alarm sensors have alarm abilities when the concrete cracks and the steel reinforcements yield. Prestressed CFRP alarm sensors are more sensitive in the low strain region, as they are able to reduce the strain when the resistance abrupt change.更多还原