非对称高墩连续刚构桥跨中合龙顶推力研究

A Study on the Thrust Force of Middle-span Closing of Continuous Rigid Frame Bridge with Asymmetric High Piers

为改善非对称高墩预应力混凝土变截面连续刚构桥成桥后墩顶产生较大偏位带来的不利影响,常在中跨合龙前实施合龙口顶推施工。以安家山河预应力连续刚构桥中跨跨中合龙口施工为研究背景,考虑边、中跨不平衡荷载、收缩徐变、合龙温差等因素确定顶推位移,基于结构力学推导了合龙口顶推力解析式,验证合龙口顶推力解析式的正确性。对比施加非对称顶推力、对称顶推力和未施加顶推力对刚构桥主梁线型、桥墩受力和主梁受力的影响。结果表明:施加对称顶推力比施加非对称顶推力对主梁控制下挠作用更加明显,使得顶推后主梁和桥墩应力水平处于合理的范围内。该研究对大跨度预应力混凝土连续刚构桥合龙施工提供理论与实践依据。

In order to improve the unfavorable effect of the large deviation of the top of the asymmetric high-pier prestressed concrete variable-section continuous rigid frame bridge after the bridge is formed,it is often implemented before the mid-span is closed.Taking the construction of Anjiashan River prestressed continuous rigid frame bridge mid-span and mid-shutter construction as the research background,considering the unbalanced load of side and mid-span,shrinkage and creep,and closing temperature difference,etc.,the pushing displacement was determined.The thrust analytical formula verifies the correctness of the closed-port thrust analytical formula.Comparing the effects of applied asymmetric thrust,symmetrical thrust and unapplied thrust on the rigid girder bridge main beam line shape,bridge pier force and main beam force.The results show that the application of symmetrical thrust is more effective than the application of asymmetrical thrust on the main beam under deflection,so that the stress level of the main beam and the pier is within a reasonable range after the thrust.The research provides theoretical and practical basis for the construction of large-span prestressed concrete continuous rigid frame bridges.