富力桃园大桥箱梁合龙区域裂缝成因分析及加固

广州市富力桃园大桥合龙区域箱梁底板预应力张拉时,较多纵向裂缝出现在箱梁底部。通过现场勘察和计算分析,发现钢束实际产生的向下拉力远大于理论值。实际荷载作用下箱梁底板横向承载力不足及过大的拉力拉断钢束孔道侧壁,导致裂缝的产生。采用粘贴钢板法和反力梁法局部加强该区域,大桥维修加固后状况良好。

Analysis and Strengthening of Cracks in Closure Zone of Box Girder of Fuli Taoyuan Bridge

A good number of longitudinal cracks occurred in the bottom part of box girder in the closure zone of Fuli Taoyuan Bridge in Guangzhou City at the time the prestress of the bottom slab of the girder was tensioned.Through observation in the field,calculation and analysis,it was found that the actual downward tensile force produced by the prestressing strands there was far greater that that of the theoretic values and the cracks were caused by the breaking of side wall concrete of prestressing ducts owing to the insufficient transverse bearing capacity of the bottom slab of the girder under the action of actual load and also owing to the excessive tensioning of the strands.The closure zone of the girder was retrofitted and locally strengthened by the steel plate binding and reaction beam methods.After the zone was strengthened,the operation conditions of the Bridge have been so far so good.