钢-混组合连续梁桥负弯矩区桥面板抗裂措施

Crack Resistance Measure for Steel-concrete Composite Continuous Girder Bridge in Negative Bending Area

大广高速某跨线桥为40+43m两跨组合连续箱梁桥,支点负弯矩区桥面板容易开裂,采用支点顶升回落的施工工艺使桥面板获得足够的压应力储备,以提高桥面板的抗裂性能。支点顶升合理高度的确定是施工中面临的重要问题。采用Midas/Civil有限元软件,通过建立全桥空间有限元模型,模拟支点顶升与回落施工过程,在保证施工安全的同时,获得合理支点顶升高度。结果表明:合理顶升高度为28cm,负弯矩区桥面板最大压应力储备为-7.9 MPa,满足桥面板的抗裂要求。

A flyover bridge on the Daguang Line Expressway is designed as a 40＋43 msteel-concrete composite continuous beam of which the concrete slab is easily cracked in the negative moment area.Obviously,the bridge deck can obtain sufficient compressive stress reserves through the fulcrum lifting up and down,and then the crack resistance of the bridge deck has been improved.However,how to determine the reasonable height of fulcrum lifting has become a significant issue in bridge construction.In this paper,a finite element software Midas/Civil is used to establish a space model of steel-concrete composite continuous beam bridge for analyzing the construction process of the fulcrum lifting up and down.Secondly,while ensuring the safety of construction,a reasonable elevation of the fulcrum will be acquired.The results show that the maximum compressive stress reserves of the negative moment area in the bridge deck was7.9 MPa in the case of a lift-down height of 28 cm.In addition,it will be able to meet the crack resistance requirements of the deck.