某重载铁路连续刚构桥底板崩裂加固设计

某重载铁路桥为(96+132+96)m预应力混凝土箱形变截面连续刚构桥,主梁采用挂篮悬臂浇注法施工,在合龙后张拉合龙束期间发现大面积的底板混凝土崩裂,主要病害还有混凝土质量缺陷及混凝土强度不足。分析桥梁病害原因后,根据维修功能、外形及使用寿命不变的原则,提出了更换底板、重新布设预应力钢束的恢复结构完整性方案,以及增加体外预应力和箱梁腹板粘贴钢板的补强加固方案。该桥加固后,通过荷载试验对桥梁承载能力进行综合评估。结果表明,桥梁结构强度、刚度均满足原设计荷载要求,加固后桥梁安全可靠。

Reinforcement Design for Bursting Cracks in Bottom Slab of a Heavy-Duty Railway Continuous Rigid Frame Bridge

A heavy-duty railway bridge is a prestressed concrete continuous rigid frame bridge with spans of(96+132+96)m,of which the main girder is variable cross-section box girder and the main beam is constructed by a hanging-basket cantilever pouring method;when the girder is closed,cracks in a large area of concrete floor are found during tension prestressed reinforcement,moreover,the defects and insufficient strength of concrete can also be detected.After analyzing the causes that are harmful to bridge,according to the principles of invariability of maintenance function,appearance,life,we put forward a scheme of resuming the structural integrity through replacing the bottom plate and rearranging prestressed steel bundles,and put forward a scheme of reinforcing the structure through increasing external prestress and box girder web paste steel plates.After bridge is reinforced,the bearing capacity of the bridge is comprehensively evaluated through load tests.The results show that the strength and stiffness of the bridge structure meet the requirements of the original design load,and the bridge is safe and reliable after reinforcement.