单向纵坡预应力混凝土斜拉桥施工监控

Construction Control on Prestressed Concrete Cable-stayed Bridge with Single-way Longitudinal Grade

闽江大桥由于采用单向纵坡,在桥梁施工过程中需要对桥梁的纵桥向位移进行监测。同时,大跨径预应力混凝土斜拉桥的施工监控,对于保证施工过程中结构的内力和变形始终处于规定范围内,以及成桥后的内力和线形符合设计要求,非常必要。通过对闽江大桥的施工过程进行理论分析、实桥测试,实现对桥梁施工过程的精细化控制。施工过程中两个最不利施工阶段的静力计算结果表明,施工过程中混凝土应力值满足要求。体系转换前后,主梁的纵桥向位移监测结果表明,阻尼器的设置可有效控制体系转换时主梁的纵桥向位移。施工监控结果表明,二期恒载完成后,桥面标高的实测值与设计院提出的计算值较为吻合;主塔偏位控制结果满足要求;全桥索力实测值与设计值一致,斜拉索索力控制结果满足要求;主梁和主塔的各应力控制截面应力没有出现拉应力,且最大压应力满足要求。

The single-way longitudinal grade was adopted in the Minjiang Bridge. Therefore,the longitudinal displacement of the bridge should be measured during the construction process of the bridge. Meanwhile,the construction control on the long-span prestreesed concrete cable-stayed bridge is of great necessity to make sure the internal force and the deformation of the structure to be within the prescribed limits during the construction process,and to make sure these after the completion of the construction to coincide with the demand of the design. The theoretical analysis and the field measurement of the construction process of the Minjiang Bridge were done in this paper,in order to control the construction process elaborately. The result of the statistic calculation on two most unfavorable construction stages indicated that,the stress of the concrete meets the requirements of the specification. The result of the longitudinal displacement measurement of the deck before and after the system transformation proved that,the installation of the damper can control the longitudinal displacement of the deck during the system transformation effectively. The result of the construction control proved that,the measured value of the deck level after the bridge deck pavement coincided with the designed value. The displacement of the main tower satisfied with the specification requirement. The measured value of the cable force coincided with the designed value. The result of the cable force control met the specification requirement. There were no tensile stress in the controlling sections of the girder and the tower,while the maximum compressive stress satisfied with the specification requirement.