连续梁、连续刚构桥施工中腹板产生裂缝的机理及对策  

The mechanism and countermeasure of cracks in webs during continuous beam and continuous rigid frame bridge constructing

作　　者：胡庆安[1] 丛慧敏[1] 齐明芹[1] 

机构地区：[1]长安大学公路学院,陕西西安710064

出　　处：《西安建筑科技大学学报（自然科学版）》2011年第3期353-355,共3页Journal of Xi'an University of Architecture & Technology(Natural Science Edition)

摘　　要：随着连续梁和连续刚构桥的广泛应用,一些桥梁在施工过程中腹板出现裂缝.本文以弹性力学为依据,运用Ansys建立连续梁、连续刚构桥三维实体模型,计算混凝土腹板三向受力情况下的主拉应力,并对比腹板内最大主拉应力与混凝土抗拉强度的关系,由此说明腹板产生裂缝的原因.结合实际桥梁,计算悬臂现浇法施工时四种工况下混凝土腹板应力,得出最大主拉应力为:0.67 MPa、0.32 MPa2、.76 MPa和0.98 MPa.由此说明竖向预应力能有效控制腹板混凝土的主拉应力,即为了预防混凝土腹板内部主拉应力超过混凝土抗拉强度,应在施工时先张拉竖向预应力,再张拉纵向预应力钢筋.With the wide application of continuous beam and continuous rigid frame bridges,cracks in webs was found in some bridges during the construction.This essay is based on Elastic Mechanics,utilizing Ansys to establish the three-dimensional model of continuous beam and continuous rigid frame bridges,calculating the maximum principal tensile stress of concrete webs which is stressed from three directions,and comparing the relationship between the maximum principal tensile stress in webs and the tensile strength of concrete.Therefore,the reason of the cracks appear on webs can be concluded.Combined with an actual bridge,adopting the method of Cantilever cast-in-place during construction with master stress of concrete in four conditions,the maximum principal tensile stress can be calculated as 0.67 MPa、0.32 MPa、2.76 MPa and 0.98 MPa.Consequently,it is illustrated that vertical prestress could control tension stress of webs effectively.That is to say,in order to prevent internal tension stress in webs from exceeding the tensile strength of concrete,one should stretch the vertical prestress firstly and then stretch the vertical prestress.

关 键 词：连续梁 连续刚构 腹板裂缝 主拉应力 施工顺序 

分 类 号：U44[建筑科学—桥梁与隧道工程] U45[交通运输工程—道路与铁道工程]