架桥机作用下的承台和盖梁应力状态研究

Researchon Stress States in Cushion Cap and Bent Cap Working with Bridge Erection Machine

在桥梁工业化、预制标准化施工中,架桥机是主要施工机械.常见的架桥机主要用于上部结构的整体吊装或拼装,预制桥墩则使用汽车吊或龙门吊进行拼装.中建八局依托绍兴市越东路智慧快速路工程研发了一种可以同时吊运桥墩和预制梁的新型架桥机,这种墩梁一体架桥机的支腿会立在承台和盖梁上,产生的压力、拉力均较大.国内外在架桥机施工方面的研究集中在架桥机和桥梁整体承载力,缺乏对支腿作用区的应力状态研究.为填补这一研究空白,文章提取5个最不利工况,采用拉压杆模型分析法和有限元软件Midas FEA,模拟桥墩受力状态.分析结果表明理论方法和软件方法均准确可行,集中力作用区的混凝土受压、钢筋应力均满足现行混凝土桥梁规范要求,而混凝土拉应力或裂缝超限.依据分析结果,文章建议在承台和盖梁的集中力作用区配置钢筋网片、螺旋筋抵抗拉应力.

In bridge industrialization and standardized precast construction,bridge erection machine is the main facility.Generally speaking,sup-structures can be assembled by bridge erection machine,while sub-structures are lifted by cranes.Based on Shaoxing Yuedong smart expressway,China Construction Eighth Engineering Division designs a new bridge erection machine called pier-girder-Erection machine.Feet of this machine which transfer huge press and pull force are laid on cushion caps and bent caps.Chinese and foreign researches mainly focus on machine and bridge girders,meanwhile ignore stress state under machine’s feet.To fill in gaps,paper extracts five load cases and builds force models of pier’s work states by strut-and-tie theory and finite element software Midas FEA.Analysis shows that both theoretical method and software model are accurate and effective.Compress stress and steel stress in focus district fit in with concrete bridge criteria,meanwhile tensile stress or crack exceed the upper limit.According to the analysis,paper proposes placing steel mesh or spiral rib in focus district to resist tensile stress.