钢-混凝土连续组合梁负弯矩区抗裂设计优化研究

Research on the Optimal Design of Negative Bending Moment Zone of Continuous Steel-Concrete Composite Girder Bridge

虽然钢-混凝土连续组合梁桥在支座处负弯矩区混凝土桥面板处施加了预应力,但仍然存在桥面板拉应力过大导致混凝土开裂的问题。为解决这一难题,以山东省广饶县小清河特大桥2号主桥为例,在对钢-混凝土连续组合梁桥的设计难点及其相关技术措施进行评价的基础上,基于部分组合技术及桥面板混凝土分步浇筑技术,对钢-混凝土连续组合梁桥的支座处负弯矩区的受力性能进行优化设计。基于Midas Civil有限元模型,重点对该组合梁桥负弯矩区的抗裂性、支点反力及全桥刚度进行研究。研究结果表明:同时使用部分组合技术和桥面板混凝土分步浇筑技术,桥梁营运期内负弯矩区混凝土桥面板始终受压;仅采用部分组合技术或桥面板混凝土分步浇筑技术,桥梁营运期内负弯矩区混凝土桥面板受到拉应力作用,且拉应力较大。由此可知,综合使用部分组合技术和桥面板混凝土分步浇筑技术,可以有效降低钢-混凝土连续组合梁桥负弯矩区混凝土桥面板的拉应力,防止混凝土桥面板开裂,改善桥梁耐久性。

Although prestress is applied to the concrete bridge deck in the negative moment zone at the support of the steelconcrete continuous box girder bridge,the problem of concrete cracking caused by excessive tensile stress still exists.Taking the Xiaoqinghe Bridge in Shandong Province as example,partial composite technology and step-by-step concrete pouring technology are applied to optimize the mechanical performance of negative moment zone at the support of steel-concrete continuous box girder bridge.Using Midas Civil finite element model,the crack resistance,fulcrum reaction and the stiffness of the bridge are analyzed in this paper.Results show that if the partial composite technology and step-by-step concrete pouring technology are applied together,the bridge deck will always be pressure.However,if only the partial composite technology or stepby-step concrete pouring technology is applied,the bridge deck is subjected to large tensile stress.Therefore,partial composite technology and step-by-step concrete pouring technology can significantly reduce the tensile stress of the concrete bridge slab of the steel-concrete continuous beam bridge,effectively avoiding the cracking of concrete bridge slab and improving the durability of the bridge.