既有钢筋混凝土桥梁加固后承载能力评定方法研究

发布时间：2018-08-13 16:34

【摘要】：随着交通运输事业的不断发展,交通需求和桥梁实际承载能力之间矛盾日益凸显。当既有桥梁承载能力不能满足交通需求时,社会经济效益较好的办法是对桥梁进行加固改造,以提升其承载能力。因此加固后桥梁承载能力评定具有重要工程意义,而对于加固之后桥梁承载能力具体评定方法规范没有相关规定,相关研究也很少,亟待研究解决。本文在总结常见加固方法基础上,以某碳纤维布(CFRP)加固的20m预应力钢筋混凝土空心板梁桥为背景,首先对加固后承载能力计算方法进行研究,并利用ANSYS建立单片预应力空心板梁模型对计算方法进行验证。然后在《公路桥梁承载能力评定规程》(TJG/T J21-2011)(以下简称《评定规程》)基础上,针对CFRP加固后桥梁的特点,建立CFRP加固钢筋混凝土梁桥的技术状况评价指标,引入CFRP加固后空鼓、粘结状况等评价指标,建立CFRP黏结强度设计计算方法和试验测试方法,并给出各指标的推荐性评价标准。对检算系数、承载能力折减系数确定方法进行修正。最后利用荷载试验进行加固后承载能力评定,并提出加固后桥梁荷载试验的要求和CFRP加固桥梁荷载试验校验系数取值范围,建立ANSYS有限元模型与荷载试验实测结果进行对比分析,并对加固效果进行分析。根据论文的研究可以得出:本文建立的CFRP加固预应力空心板梁的承载能力计算方法能够满足计算要求;CFRP加固桥梁新增评价指标及评定标准、修正后的检算系数、承载能力折减系数确定方法对于加固后桥梁更加合理。CFRP粘结强度设计值计算方法及粘结强度评定标准合理;荷载试验综合评价表明该桥加固后承载能力满足要求,加固效果良好。CFRP加固能有效抑制梁体裂缝的开展,极限承载力大幅提高,受压区混凝土加固前后应力基本没有变化,梁底混凝土所受最大拉应力值减小,受拉区预应力钢绞线应力值减小,中和轴下移,说明CFRP加固能改善结构梁桥受力性能,提高结构承载能力。
[Abstract]:With the continuous development of transportation, the contradiction between traffic demand and actual bearing capacity of bridges is becoming increasingly prominent. When the bearing capacity of the existing bridge can not meet the traffic demand, the better method of social and economic benefit is to strengthen and transform the bridge in order to enhance its bearing capacity. Therefore, the evaluation of the bearing capacity of strengthened bridges is of great engineering significance, but there are no relevant rules and regulations for the concrete assessment methods of the bridge's bearing capacity after reinforcement, and there are few related studies, which need to be studied and solved urgently. On the basis of summing up the common reinforcement methods and taking a 20m prestressed reinforced concrete hollow slab girder bridge strengthened with carbon fiber sheet (CFRP) as the background, this paper first studies the calculation method of the bearing capacity after reinforcement. The calculation method is verified by using ANSYS to build a single prestressed hollow slab beam model. Then, based on TJG/T J21-2011 (TJG/T J21-2011), according to the characteristics of the bridge strengthened by CFRP, the evaluation index of the technical condition of reinforced concrete girder bridge strengthened by CFRP is established, and the hollow drum is introduced into the reinforced concrete bridge strengthened by CFRP. The calculation method of CFRP bond strength design and test method are established, and the recommended evaluation criteria of each index are given. The determination method of checking coefficient and load capacity reduction coefficient is modified. Finally, load test is used to evaluate the load capacity of strengthened bridge, and the requirements of load test of strengthened bridge and the range of check coefficient of load test for CFRP strengthened bridge are put forward. The ANSYS finite element model is established and the measured results of load test are compared and analyzed. According to the research of this paper, it can be concluded that the calculation method of bearing capacity of prestressed hollow slab beam strengthened by CFRP in this paper can meet the requirements of calculation, such as the new evaluation index and evaluation standard, and the revised checking coefficient. The calculation method of the design value of CFRP bond strength and the evaluation standard of bond strength are more reasonable, the comprehensive evaluation of load test shows that the bearing capacity of the bridge after strengthening meets the requirements. The reinforcement effect is good. CFRP can effectively restrain the crack development of beam body, the ultimate bearing capacity is greatly increased, the stress of concrete in compression zone before and after strengthening is basically unchanged, and the maximum tensile stress of concrete under beam decreases. The stress value of prestressed steel strands in tension zone is reduced and the axis is shifted down, which indicates that CFRP reinforcement can improve the mechanical performance of structural beam bridges and increase the bearing capacity of the structures.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U445.72

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