重载交通下桥梁结构的疲劳特性试验研究

发布时间：2018-05-02 04:09

本文选题：重载交通 + 预应力混凝土梁　；参考：《河北工业大学》2015年硕士论文

【摘要】：近几十年来,我国的公路交通运输发展迅速,重载车辆越来越多,由此引起的桥梁结构的破坏现象也越来越严重。按以前的规范设计的在役桥梁并不能承受重载车辆的碾压,出现了明显的疲劳破坏现象,甚至有的桥梁发生垮塌。目前对重载交通下桥梁结构疲劳特性的研究还不是很多,因此,对这方面的研究就显得特别有必要,同时研究成果也可为以后的设计提供必要的参考,有十分重要的实际和理论意义。本文的试验梁都是由某实际公路梁缩尺而来,共四根,其中一根做静载试验,另三根进行等幅疲劳荷载作用下的疲劳试验。对试验结果进行分析研究可以得到如下主要结论:1.试验桥梁在不同应力幅作用下发生疲劳破坏时预应力钢筋与普通钢筋的应力幅比为0.595;2.试验梁受压区混凝土的应变、普通钢筋及预应力钢筋的应变和跨中最大挠度随疲劳加载次数的发展都基本符合“三阶段”规律;3.在梁临近破坏时,非预应力钢筋和受压区混凝土的动态应力幅值约是静载应力幅值的1.15-1.25倍,预应力钢筋约为1.05-1.15倍;跨中最大挠度在初始阶段动态挠度幅值约是静态挠度幅值的1.05-1.10倍,试验后期约为1.10-1.25倍;4.在临近破坏时各试验梁的混凝土应变、钢筋应力、跨中挠度和最大裂缝宽度都基本相同;5.根据试验所得数据拟合出试验梁中非预应力钢筋的疲劳寿命曲线;6.经过200万次疲劳荷载循环后没有疲劳破坏的梁其抗弯刚度只损失了约20%左右,而经过200万次循环后破坏的梁其抗弯刚度还有一定的存留,损失都约50%左右,只是在不同应力幅下的损失速度不同,宏观上表现为试验梁的疲劳寿命不同。
[Abstract]:In recent decades, highway transportation has developed rapidly in China, and more and more heavy-haul vehicles have been used. The damage of bridge structure caused by this phenomenon is becoming more and more serious. The existing bridges designed according to the previous codes can not withstand the rolling of heavy-duty vehicles, which results in obvious fatigue failure and even collapse of some bridges. At present, there are not many researches on the fatigue characteristics of bridge structure under heavy traffic. Therefore, it is particularly necessary to study this aspect, and the research results can also provide the necessary reference for the future design. It has very important practical and theoretical significance. The test beams in this paper are all from a practical highway beam, which consists of four beams, one of which is subjected to static load tests and the other three to fatigue tests under the same amplitude of fatigue load. By analyzing the results of the experiment, we can get the following main conclusion: 1. The stress amplitude ratio of prestressed steel bar to ordinary steel bar is 0.595m2 when fatigue failure of test bridge occurs under different stress amplitudes. The strain of concrete in compression zone, the strain of ordinary steel bar and prestressed steel bar and the maximum deflection of span with the development of fatigue loading times basically accord with the "three-stage" rule. When the beam is near failure, the amplitude of dynamic stress is 1.15-1.25 times of that of static stress, and the amplitude of prestressed steel bar is 1.05-1.15 times of that of prestressed concrete. The amplitude of dynamic deflection is 1.05-1.10 times of that of static deflection in the initial stage and 1.10-1.25 times of that of static deflection in the later stage of the experiment. The concrete strain, reinforcement stress, mid-span deflection and maximum crack width of the test beams are almost the same as those of the test beams near failure. According to the test data, the fatigue life curve of non-prestressed steel bar of test beam is fitted. After 2 million cycles of fatigue load, the flexural stiffness of the beams without fatigue failure has only lost about 20%, but after 2 million cycles, the flexural stiffness of the beams destroyed after 2 million cycles still remains, and the loss is about 50%. The fatigue life of the test beam is different macroscopically, but the loss velocity is different under different stress amplitude.
【学位授予单位】：河北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441.4;U446

【共引文献】