大悬臂构造主梁翼缘施工阶段裂缝成因分析

Analysis on crack causes in the construction stage of the main girder flange of large cantilever structure

为防止大悬臂构造主梁翼缘施工阶段裂缝的产生,对某大悬臂构造矮塔斜拉桥主梁翼缘施工过程中产生的裂缝成因进行分析。结果表明:节段间混凝土收缩差异较大是翼缘开裂的主要原因;主梁由于采用大悬臂构造,使翼缘产生了较大的温度收缩与干缩;相比于降温引起的温度收缩,混凝土的干缩更为显著。采取缩短节段间浇筑时间间隔、加强主梁翼缘养护,添加适量膨胀剂等手段进行防治,以期可为类似工程提供借鉴与参考。

In order to prevent the occurrence of cracks in the construction stage of the main girder flange of large cantilever structure,the causes of cracks of the main girder flange in construction stage of an extradosed ca b lestayed bridge with large cantilever structure are analyzed.The results show that the huge difference of concrete shrinkage between segments is the main cause of flange cracking;because the main girder adopts a large cantilever structure,the flange has a larger temperature contraction and air shrinkage;compared with the temperature shrinkage caused by temperature reduction,the air shrinkage of concrete is more significant.Such measures are taken as shortening the pouring interval of segments,enhancing the maintenance of the main girder flange and adding proper amount of swelling agent,which is expected to provide references for similar projects.