现浇预应力混凝土连续箱梁开裂分析及其影响因素

Cracking Analysis and Influencing Factors of Cast-in-Situ Prestressed Concrete Continuous Box Girder

以某互通立交桥连续箱梁为研究对象,针对箱梁边跨梁端腹板开裂的现象,采用经过验证的3D实体有限元仿真模型,对代表联4×30 m连续箱梁进行从施工到成桥的全过程受力状态分析,对箱梁混凝土进行开裂模拟。结果表明,腹板预应力钢束锚固位置的变更导致在施工短暂工况下腹板主拉应力过大是箱梁开裂的主要原因。进一步对箱梁开裂的影响因素分析表明,腹板预应力钢束锚固位置及锚固槽口间距是控制梁端腹板主拉应力的关键因素,在今后设计中应予以重视。

Taking the continuous box girder of an interchange as the research object,aiming at the cracking phenomenon of the end web of the side span girder of the box girder,this paper adopts the verified 3D solid finite element simulation model to analyze the stress state of the representative 4×30m continuous box girder from construction to completion,and simulates the cracking of the concrete of the box girder.The results show that the main reason for the cracking of box girder is that the main tensile stress of webs is too large under short construction conditions due to the change of anchorage position of web prestressed steel.Further analysis of the factors affecting the cracking of box girders shows that the distance between the anchorage position of web prestressed steel and anchorage grooves is the key factor to control the main tensile stress of the beam-end web,which should be paid more attention to in the future design.