某人行桥振动测试及地震作用下的动力分析

发布时间：2018-02-02 20:21

本文关键词： 有限单元法振动测试抗震分析　出处：《郑州大学》2016年硕士论文　论文类型：学位论文

【摘要】：桥梁在交通中起咽喉作用,近年来除建设了更多大型复杂桥梁外,中小跨径的桥梁建设也在持续,在大范围内开展的桥梁调查中,现役钢筋混凝土桥梁常发生混凝土剥落、开裂,钢部件锈蚀,附属件损坏等问题,因而其安全性成为各方关注的焦点。近几十年来有限元的方法在桥梁模态分析中得到广泛应用,但由于设计和施工中存在差异,以及缺乏管理维护等原因,有限元模型与实际情况并不一致,计算结果与实际情况存在差异,为此基于振动测试的模态参数识别技术得到长足发展。实际中桥梁结构往往体型复杂、存在隐蔽部位,且不适宜中断交通,考虑到检测目标和测试成本,基于环境激励的动力测试手段更具应用前景。针对某人行桥,本文分别进行了有限元模态分析和实验模态分析,对比验证了有限元模型的合理性,并在此基础上分别基于反应谱法和时程分析法对该桥进行了动力分析计算及结果对比,主要工作如下:(1)结合工程设计图纸建立了某人行桥的三维有限元分析模型并进行了有限元模态分析。按对钢筋混凝土材料的模拟方式不同,分为三种模型,分别模拟得到了各阶振型及其对应的频率、有效质量和振型参与系数,对提取的模态参数做分析比较,各模型频率变化趋势一致,说明模型的合理性。针对该桥梁上部结构,通过分析其累计有效质量系数,超过90%时保证提取到了足够的模态,结果为前14阶,对应频率为184Hz。(2)根据有限元模拟结果制定实验方案并进行了实验模态分析。按激励方式的不同,分为两种工况对该人行桥进行了现场动力测试,得到各自的加速度时程记录。对记录结果进行筛选、处理,识别出模态参数,与有限元模拟结果进行对比分析,验证了有限元模型的合理性,试验桥梁无明显损伤,可满足正常使用。(3)在模态分析的基础上,对该人行桥分别基于反应谱法和时程分析法进行地震荷载作用下的动力分析。基于计算模态和实验模态分析的结论,考虑结构阻尼和材料弹塑性,建立新的动力模型,施加合适的地震荷载,分析得到相应的结构响应和应力情况,并对结果进行对比分析,结果都在安全允许范围内。
[Abstract]:Bridge plays an important role in traffic. In recent years, in addition to the construction of more large and complex bridges, the construction of small and medium span bridges is also continuing. Concrete spalling, cracking, corrosion of steel parts and damage of accessories often occur in existing reinforced concrete bridges. In recent decades, the finite element method has been widely used in bridge modal analysis, but due to the differences in design and construction, as well as lack of management and maintenance. The finite element model is not consistent with the actual situation, and the calculation results are different from the actual situation. Therefore, modal parameter identification technology based on vibration testing has been developed greatly. In practice, bridge structure is often complicated. There are hidden parts, and it is not suitable to interrupt traffic. Considering the detection target and test cost, the dynamic test method based on environment excitation has more application prospect. In this paper, the finite element modal analysis and experimental modal analysis are carried out, and the rationality of the finite element model is verified by comparison. On this basis, the dynamic analysis and comparison of the bridge are carried out based on the response spectrum method and time history analysis method, respectively. The main work is as follows: (1) combined with the engineering design drawings, the three-dimensional finite element analysis model of the bridge is established and the finite element modal analysis is carried out. The simulation methods of reinforced concrete materials are different. It is divided into three kinds of models, respectively, each model and its corresponding frequency, effective mass and mode participation coefficient, the extracted modal parameters are analyzed and compared, each model frequency change trend is the same. The rationality of the model. According to the bridge superstructure, by analyzing its cumulative effective mass coefficient, it is guaranteed to extract enough modes when over 90, the result is the first 14 steps. According to the results of finite element simulation, the experiment scheme was established and the experimental modal analysis was carried out. According to the different excitation modes, the dynamic test of the footbridge was carried out on the spot under two working conditions. The acceleration time history records are obtained. The results are screened, processed, modal parameters are identified, and compared with the finite element simulation results, the rationality of the finite element model is verified. The test bridge has no obvious damage and can meet the normal use. 3) on the basis of modal analysis. The dynamic analysis of the footbridge under seismic load is carried out based on the response spectrum method and the time-history analysis method respectively. Based on the conclusion of the computational mode analysis and the experimental modal analysis, the damping of the structure and the elastoplasticity of the material are considered. A new dynamic model is established, appropriate seismic load is applied, the corresponding structural response and stress are obtained, and the results are compared and analyzed. The results are all within the safe allowable range.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U441.3;U448.11

【相似文献】