Abstract:With the development of the times, the entire society has put forward higher and higher requirements for the construction of bridge structures. In order to alleviate the traffic pressure, promote the economic development, reduce the engineering costs and reduce the social impact, more and more existing bridges will be widened and rebuilt continuously to bear the social responsibilities. In the reconstruction and expansion project of Jiajin Section in G15 Highway, there are a large number of existing bridges to be reconstructed, in which the hollow slab beams are widened by the method of connecting the superstructure and not connecting the substructure. Three widening schemes for its hollow slab beams are compared and selected, and the impact of the settlement of the newly built structure on the existing hollow slab beams and joints is calculated and analyzed, which provides a certain reference for the design of bridge reconstruction and extension projects.