重载PC连续刚构桥体外预应力加固及效果研究

Study on external prestressing reinforcement and effect of PC continuous rigid frame bridge

为探究预应力混凝土连续刚构桥的加固方法,首先用结构有限元计算软件对原桥结构进行复核验算,然后根据桥梁病害修正相关参数后对桥梁现状重新验算,修正相关参数后的中跨理论挠度值与实际下挠吻合度较好,同时抗裂验算结果与实际病害情况相符,故计算结果验证了修正参数后的理论计算模型与实桥吻合。依据修正参数后的模型验算结果,提出了体外预应力加固方案,并对该加固方案进行数值模拟验算。模拟结果表明:体外预应力张拉后,桥梁极限承载能力、主梁压应力储备均提升明显;在加固施工完成后,采用桥梁荷载试验验证了加固方案的有效性。最后得出在连续刚构桥抗裂性能及承载能力不足时,体外预应力加固为有效的加固措施。

In order to explore the reinforcement method of prestressed concrete continuous rigid frame bridge, firstly, the structural finite element software is used to recheck the bearing capacity of original bridge, and then the bridge is recalculated after modifying relevant parameters according to bridge diseases. The theoretical deflection of midspan after modifying relevant parameters is good agreement with the actual downward deflection, and the crack resistance calculation results are in comformity with the actual disease, therefore, the calculation results verify that the theoretical calculation model with modified parameters is consistent with the actual situation of bridge.According to the checking results, the external prestressing reinforcement scheme is proposed, and the numerical simulation checking calculation is carried out for the reinforcement scheme. The checking results show that: after the external prestressing tension, the ultimate bearing capacity of the bridge and the compressive stress reserve of the main beam are significantly improved;after the reinforcement construction is completed, the bridge load test verifies the effectiveness of the reinforcement scheme. Finally, it is concluded that external prestressing is an effective reinforcement measure when the crack resistance and bearing capacity of continuous rigid frame bridge are insufficient.