跨海大桥U-RC组合桥墩设计

发布时间：2018-03-09 02:26

本文选题：桥梁工程　切入点：跨海大桥　出处：《交通运输工程学报》2017年04期 　论文类型：期刊论文

【摘要】：为解决跨海桥梁桥墩施工与防腐问题,提出了超高性能混凝土(UHPC)-钢筋混凝土(RC)组合桥墩新结构,简称U-RC组合桥墩,以UHPC外筒作为永久模柱,现浇内核钢筋混凝土;以平潭海峡大桥为工程背景,开展了U-RC组合桥墩的结构设计与计算,并与原设计方案的工程量和造价进行了比较;进行了3根内核RC柱、3根UHPC模柱、3根U-RC组合桥墩的极限承载力试验,测量了试件的混凝土纵向应变与横向应变,研究了试件的破坏形态与裂缝发展过程,得到了试件的极限承载力试验值,分析了U-RC组合桥墩的受力性能。研究结果表明:U-RC组合桥墩的承载力大于设计内力,满足现行规范要求;采用UHPC模柱取代钢模板的桥墩设计方案,可节约钢材约2 410t,工程造价节省约30%;3根UHPC圆筒的极限荷载均值为1 342kN,3根RC柱的极限荷载均值为1 370kN,二者之和小于3根U-RC组合桥墩极限荷载均值3 033kN,说明UHPC模柱对核心混凝土有一定的套箍作用,采用简单迭加方法计算U-RC组合桥墩的轴压极限承载力是可行且偏保守的;在轴压试验中,U-RC组合桥墩的破坏模式为核心混凝土的横向变形导致UHPC模柱出现竖向裂缝,并与核心混凝土在界面处分离;达到极限荷载破坏时,外包UHPC层出现纵向裂缝,荷载增大,裂缝增长,并有混凝土剥落现象,但U-RC组合桥墩破坏时其外包UHPC层纵向应变未达到极限压应变。
[Abstract]:In order to solve the problem of bridge pier construction and anticorrosion of cross-sea bridge, a new structure of UHPC-RC composite pier is put forward, which is referred to as U-RC composite pier. UHPC outer cylinder is used as permanent mould column and in-situ core reinforced concrete is put forward. Taking the Pingtan Strait Bridge as the engineering background, the structural design and calculation of U-RC composite pier are carried out, and the engineering quantity and cost of the original design are compared. In this paper, the ultimate bearing capacity of three RC columns with three core RC columns and three UHPC formwork columns and three U-RC composite piers are tested. The longitudinal and transverse strain of concrete is measured, and the failure mode and crack development process of the specimens are studied. The ultimate bearing capacity test value of the specimen is obtained and the mechanical performance of U-RC composite pier is analyzed. The results show that the bearing capacity of the U-RC composite pier is larger than the design internal force and meets the requirements of the current code. The design scheme of bridge pier using UHPC die column instead of steel formwork, Steel can be saved about 2 410 t, and construction cost can be saved about 30 ~ 3 UHPC cylinders. The average limit load of 3 RC columns is 1370 KN, and the sum of the two is less than 3 U-RC composite piers with a mean limit load of 3 033 KN. The core concrete has the function of hoop, It is feasible and conservative to calculate the ultimate bearing capacity of U-RC composite piers by using simple superposition method, and the failure mode of U-RC composite piers is the transverse deformation of the core concrete, which leads to vertical cracks of UHPC formwork columns. And separated from the core concrete at the interface, when the ultimate load is reached, the outer UHPC layer appears longitudinal cracks, the load increases, the cracks increase, and the concrete spalling occurs. However, the longitudinal strain of the UHPC layer is not up to the ultimate compressive strain when the U-RC composite pier is destroyed.
【作者单位】：福建工程学院福建省土木工程新技术与信息化重点实验室;福州大学土木工程学院;
【基金】：国家自然科学基金项目(U1305245)
【分类号】：U443.22

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