悬臂施工过程中箱梁腹板斜裂缝成因分析

Analysis of Formation Causes of Diagonal Cracks in Box Girder Web During Cantilever Construction

结合某主跨为240m的大跨径预应力混凝土连续刚构桥工程实例,在悬臂浇筑施工过程中箱梁腹板出现的斜裂缝通过局部有限元数值模拟、裂缝成因理论、施工过程影响因素3个方面对其成因进行了分析。结果表明,有限元局部模拟分析没有产生裂缝,斜裂缝主要由腹板下弯束产生的径向力和腹板的横向拉应力产生,施工过程中材料原因、环境温度、混凝土拆模过早,临时堆载超载,预应力张拉过大等因素也可能导致腹板斜裂缝产生。针对分析结果提出裂缝处理和预防措施。

This paper investigates the formation causes of diagonal cracks in box girder web in cantilever cast process through finite element simulation, formation causes of diagonal cracks and influencing factors in construction process analysis. In the process, a prestressed concrete continuous rigid frame bridge, which has a main span of 240 meters and is under constructing is analyzed. The results show that partial simulation of finite element analysis has no cracks. Diagonal cracks in box girder web mainly caused by radial force generated by web＇ s bent-down tendon and web transverse tensile stress. The material reasons, ambient temperature, concrete form removal premature, temporary load overload, tendons tensile stress too large and other factors can also lead to web cracks. According the results of the analysis, the crack treatment and preventive measures were taken correspondingly.