【作者】 张骏；

【导师】 胡大琳； 叶征伟；

【作者基本信息】 长安大学 ， 建筑与土木工程（专业学位）， 2019， 硕士

【摘要】 预应力混凝土连续梁桥是我国交通路网中的主要桥型,该桥型数量逐年增加,部分大跨径PC连续梁桥在建成运营数年后经检测发现存在下挠与开裂等病害,严重影响桥梁正常使用,需通过加固恢复其使用功能,体外预应力加固是一项适用于该桥型的有效加固方法。本文针对一座跨径为62m+100m+62m的PC连续梁桥进行结构现状分析与体外预应力加固方法研究。首先基于桥梁病害与荷载试验结果进行病害成因分析,为评定桥梁现状提供研究方向;然后采用有限元软件建立桥梁整体模型进行腹板与底板病害成因定量分析,重点分析有效预应力不足与重载车辆对结构的影响,进而结合桥梁病害与荷载试验结果评定桥梁现状并进行结构检算;接着建立局部有限元模型分析箱梁顶板裂缝成因并判断箱梁现状,重点分析温度梯度与重载车辆对箱梁顶板受力的影响;然后基于桥梁现状进行体外预应力加固方案设计,重点进行体外预应力束设计研究与锚固齿块设计研究,最终对加固后桥梁进行结构验算。实例桥研究表明有效预应力低于设计值与超载车辆共同作用是梁体下挠与开裂的主要原因,竖向温度梯度与超载车辆共同作用是造成箱梁顶板纵向裂缝的主要原因;建议当采用减小桥面铺装层厚度改善结构受力时应严格验算改造后桥面板抗裂性能;本文在进行体外预应力加固方案设计时改进了体外预应力束面积估算公式,提高了体外预应力束设计效率;同时通过对独立锚固齿块与角隅锚固齿块进行专门研究,并参考公路桥规提出了角隅锚固齿块配筋设计计算公式,方便桥梁设计人员进行角隅锚固齿块设计;加固后桥梁结构验算结果表明体外预应力加固方法能有效提高桥梁抗裂性能,恢复桥梁正常使用功能;最后建议加强加固后桥梁的运营管理,严禁超载车辆过桥。更多还原

【Abstract】 Prestressed concrete continuous girder bridge is the main bridge type in China’s traffic network.The number of this type of bridges is increasing year by year.Some long-span PC continuous girder bridges were found to have deflection and cracking after several years of operation,which affected the normal using function of the bridges seriously.It is necessary to restore its using function by reinforcement.External prestress reinforcement is an effective method suitable for reinforcing this type of bridges.In this paper,the analysis of present condition and external prestress reinforcement method of a PC continuous beam bridge with a span of 62m+100m+62m are studied.Firstly,the causes of the diseases are analyzed based on the results of the bridge diseases and load test,which provides the research direction for assessing the bridge condition.Then,quantitative analysis of the causes of web disease and bottom plate disease is carried out by using the finite element software to establish the integral model of the bridge,focusing on analyzing the impact of the insufficient effective prestress and heavy vehicles on the structure.Assessing the bridge condition and carrying out the structure check based on the results of the bridge diseases and load test.After that,the causes of cracks of box girder roof are analyzed and the box girder condition is judged by establishing local finite element mode.Focusing on analyzing the impact of the temperature gradient and heavy vehicles on the stress of the top plate of the box girder.Then,external prestress reinforcement scheme is designed based on the bridge condition,focusing on the study of the external prestressing design and the anchor block design.Finally,the structure check is carried out on the reinforced bridge.The study of the example bridge shows that the combined effect of insufficient effective prestress and overload vehicles is the main reason for the deflection and cracking of the girder,the combined effect of vertical temperature gradient and overload vehicles is the main reason for the longitudinal cracks in top plate of the box girder;It is recommended that the crack resistance of the reconstructed bridge deck should be checked strictly when reducing the thickness of the bridge deck pavement to improve the structure stress;In this paper,the formula of estimating external cable area is modified and the efficiency of designing reinforcement scheme is improved;At the same time,the method of designing corner anchor block is proposed,by specializing the independent anchor block and the corner anchor block,and referring to the code for highway bridges,which is convenient for bridge designers to design corner anchor block;The check result of the reinforced bridge shows that the external prestress reinforcement scheme can effectively improve the crack resistance and restore the normal using function of the bridge;Finally,it is commended to strengthen the management of the reinforced bridge,and it is forbidden for overloaded vehicles to cross the bridge.更多还原