钢筋混凝土结构构件加固后的可靠度研究

发布时间：2018-07-23 11:51

【摘要】：随着建筑物使用年限的增加,越来越多的建筑物已超过或接近其设计使用年限,因此均存在着一定程度的安全隐患,需要重新对这些建筑物进行鉴定。鉴定的内容一般包括安全性、适用性和耐久性,当鉴定结果中有任何一项性能指标不满足规范要求时,就须对建筑物进行技术处理,处理的方式之一是进行维修加固,使其重新满足承载能力极限状态和正常使用极限状态的要求。针对构件的承载能力极限状态,具体做法是首先采用鉴定规范对既有建筑的安全性进行评定,当评定结果不满足时,采用现行的加固规范进行加固处理。但是现行的加固规范的可靠度水平不明确,本文主要做了以下几个方面的工作:(1)本文考虑既有结构加固改造的可靠性计算和拟建结构不同,针对已使用一定年限的既有混凝土结构构件,考虑大气环境下钢筋锈蚀、混凝土强度的衰减,以及后续使用年限的不同对活荷载进行修正的影响,提出既有结构可靠度计算的方法。研究表明:对于既有结构应充分考虑其特点,进行可靠指标的分析。(2)对钢筋混凝土轴心受压柱,按加固规范的方法进行增大截面法设计后,对原有部分和新加部分的可靠指标分别进行计算,原有部分按既有结构可靠指标的计算方法进行,新加部分按拟建结构可靠指标的计算方法进行。并对影响两部分可靠指标的因素进行了分析。分析表明:可以通过调整卸载比例以及钢筋承担的荷载比例,以达到使新老两部分钢筋混凝土的可靠指标尽可能相协调。(3)对粘钢加固钢筋混凝土梁,考虑加固时刻的应力水平以及粘贴钢板的应变滞后效应,按照加固规范的公式,采用一次二阶矩法对加固后的梁进行可靠度分析。(4)针对实际中较为关心的何种随机输入参数对输出结果的影响较大这个问题,本文采用有限元分析软件Ansys对粘钢加固梁建立分析模型,采用其中的可靠度分析模块对该梁进行加固后的灵敏度分析,分析表明:混凝土抗压强度以及外荷载对加固后梁的应力和位移的影响最大。
[Abstract]:With the increase of the service life of buildings, more and more buildings have exceeded or close to their design life, so there is a certain degree of hidden danger of safety, so it is necessary to re-identify these buildings. The contents of the appraisal generally include safety, applicability and durability. When any of the performance indexes in the appraisal result do not meet the requirements of the specification, the technical treatment of the building is required, and one of the ways to deal with it is to carry out maintenance and reinforcement. Make it meet the limit state of carrying capacity and the limit state of normal use again. In view of the limit state of the bearing capacity of the members, the first step is to use the appraisal code to evaluate the safety of the existing building, and when the evaluation result is not satisfied, the existing reinforcement code is adopted to reinforce the structure. However, the reliability level of the existing reinforcement code is not clear. The main work of this paper is as follows: (1) this paper considers the reliability calculation of existing structures and the different structures to be built. Considering the corrosion of steel bar in atmospheric environment, the attenuation of concrete strength, and the influence of different service life on the modification of live load, the existing concrete structural members that have been in use for a certain number of years are considered. A method for calculating the reliability of existing structures is presented. The results show that the existing structures should be fully considered for their characteristics, and the reliability index should be analyzed. (2) after the reinforced concrete columns under axial compression are designed by the method of reinforcement code, The reliability indexes of the original part and the new addition part are calculated separately. The original part is calculated according to the existing structural reliability index, and the new part is calculated according to the method of calculating the proposed structural reliability index. The factors that affect the reliability index of two parts are analyzed. The analysis shows that the reliability index of the new and old reinforced concrete can be coordinated as much as possible by adjusting the unloading ratio and the load ratio of steel bars. (3) strengthening reinforced concrete beams with bonded steel, Considering the stress level at the strengthening time and the strain lag effect of the steel plate, according to the formula of the reinforcement code, The first order second moment method is used to analyze the reliability of the strengthened beam. (4) in order to solve the problem of which random input parameters have great influence on the output results in practice, the first order second moment method is used to analyze the reliability of the strengthened beam. In this paper, the finite element analysis software Ansys is used to establish the analysis model of the steel bonded strengthened beam, and the reliability analysis module is used to analyze the sensitivity of the strengthened beam. The analysis shows that the compressive strength and external load of concrete have the greatest influence on the stress and displacement of the strengthened beam.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU375;TU311.2

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