增大截面加固受损混凝土梁疲劳性能试验研究

发布时间：2018-04-19 14:41

本文选题：增大截面加固法 + 疲劳　；参考：《重庆交通大学》2015年硕士论文

【摘要】：现如今,随着土木工程不断建设发展,新的设计理念日tg完善,我国桥梁事业,处于一个趋向稳定的态势。越来越多的科学工作者把目光转向了已成桥的管理和养护方面。由于自然环境以及结构自身不断老化等因素,钢筋混凝土在服役期限内,往往会出现各种各样的损伤,达不到设计的寿命要求。本文依托实际工程,采用增大截面法进行相关方面的试验设计,系统的研究和分析加固后的钢筋混凝土简支梁桥疲劳性能,设计了相关的试验研究方案。以钢筋混凝土梁的损伤情况以及不同荷载作用下钢筋的应力水平为研究对象,采用增大截面的方法对钢筋混凝土梁进行了加固处理,并进行了疲劳试验,分析了循环荷载作用下加固梁相关的疲劳性能。主要研究了以下方面:①研究了使用增大截面法加固混凝土梁的力学性能和破坏形态。试验共设计了三组试件来进行对比分析,第一组试件共2片梁,1片未经过加固直接进行静载试验得到原梁极限承载能力以指导试验梁的受损加载(约为极限荷载u1P的0.85倍),另外1片加固后再进行静载试验以测得加固后梁的极限承载能力(u2P),指导试验梁的疲劳加载,同时得到了加固后混凝土梁的静力性能。②研究了疲劳循环的荷载水平对加固混凝土梁疲劳性能的影响。第二组试件共3片梁,加固前不做受损处理进行疲劳试验。疲劳荷载的下限值统一取0.1u2P,上限分别取0.5u2P、0.7u2P以及0.9u2P。研究在不同应力条件下,加固梁的疲劳特性。③研究了预受损对增大截面法加固混凝土梁疲劳性能的影响。第三组试验共2片梁。2片梁在加固前均按0.85uP做了受损处理,然后进行疲劳试验,疲劳试验荷载水平与第二组后2片梁相同以进行对比,研究前期预损伤行为对加固梁疲劳性能的影响。④结合试验数据,通过线性拟合得到循环荷载作用下,增大截面加固混凝土梁的S?N曲线,为用增大截面加固的桥梁结构的寿命预测提供了依据。⑤对疲劳损伤累积的机理进行了探讨。在试验数据和理论分析的基础上运用剩余刚度的方法对增大截面法加固的混凝土试验梁的损伤进行了分析验证,得到了结构疲劳破坏全过程三阶段的发展规律。
[Abstract]:Nowadays, with the development of civil engineering and the improvement of new design concept, the bridge industry in our country is in a stable situationMore and more scientists are turning their eyes to the management and maintenance of the bridge.Due to the aging of the natural environment and the structure itself, various kinds of damage often occur in the service life of reinforced concrete, which can not meet the design life requirements.In this paper, based on the actual engineering, using the method of increasing section to carry out the related experimental design, the fatigue performance of reinforced concrete simply supported beam bridge is studied and analyzed systematically, and the related experimental research scheme is designed.Taking the damage of reinforced concrete beam and the stress level of steel bar under different loads as the object of study, the reinforced concrete beam was strengthened with the method of increasing section, and the fatigue test was carried out.The fatigue behavior of strengthened beams under cyclic load is analyzed.In this paper, the mechanical properties and failure modes of concrete beams strengthened with the method of increasing section are studied in the following aspects: 1.Three groups of specimens were designed for comparative analysis.In the first group of specimens, two beams and one piece of beam were tested under static load without reinforcement. The ultimate load-bearing capacity of the original beam was obtained to guide the damaged loading of the test beam (about 0.85 times of the limit load U1P), and the other one piece was strengthened and then tested under static load.The ultimate load-bearing capacity of the strengthened beam is measured and the fatigue loading of the test beam is guided.At the same time, the static behavior of reinforced concrete beam is obtained. 2. The influence of fatigue cyclic load level on the fatigue behavior of reinforced concrete beam is studied.The second group consists of 3 beams. Fatigue tests are carried out without damage treatment before reinforcement.The lower limit of fatigue load is 0.1u2P, the upper limit is 0.5u2P0. 7u2P and the upper limit is 0.9u2P.In this paper, the fatigue behavior of strengthened beams under different stress conditions is studied. 3. The effect of pre-damage on the fatigue behavior of reinforced concrete beams strengthened by increasing cross-section method is studied.In the third group, 2 beams were damaged according to 0.85uP before reinforcement, and then fatigue tests were carried out. The load level of fatigue test was the same as that of the second group.The influence of pre-damage behavior on fatigue behavior of strengthened beams was studied. 4. Based on the experimental data, the Sn-N curves of reinforced concrete beams were obtained by linear fitting under cyclic load.The mechanism of fatigue damage accumulation is discussed in this paper.On the basis of experimental data and theoretical analysis, the residual stiffness method is used to analyze and verify the damage of concrete test beams strengthened by increasing cross-section method, and the three-stage development rule of fatigue failure of structures is obtained.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U445.72

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