某刚构桥悬浇施工过程中腹板裂缝成因分析及处置措施

The Cause Analysis and Treatment Measures of Web Cracks in the Process of Cantilever Casting Construction for a Rigid Frame Bridge

某刚构桥采用悬臂浇筑法施工,当施工至1号块并张拉腹板束时,在多个T构的腹板上发现了裂缝,该裂缝均位于腹板内侧槽口下方。通过建立实体有限元模型对其成因进行分析,发现腹板束下弯角度过大,导致槽口下方出现较大拉应力是裂缝形成的主要原因,而之所以仅出现在内侧,是由于顶底板和腹板组成框架结构,使得腹板内侧拉应力大于外侧。通过对竖向预应力效应进行分析发现:如果竖向预应力先于纵向预应力张拉,则此裂缝就不会出现。

The cantilever casting construction was employed for a rig frame bridge. When the construction was done to No.1 block and the web bundle was tensioned, cracks were found on various T-shaped webs. with the locations below notch of web inside. This paper analyzed its causes by establishing solid finite element model and discovered that the bending angle under web bundle was oversized, which resulted in larger tensile stress below notch that was the main reason for crack formation. However, the reason why the crack only occurred inwardly was due to frame structure formed by bottom and top beds and web, which made the tensile stress of web inside bigger than that of outside. It was found by analyzing vertical prestressing effect that the crack did not occur if vertical prestress tensioned prior to longitudinal prestress.