Research About The Static And Dynamic Mechanics Characteristics Of An Extended Long-span Prestressed Concrete Rigid-frame Bridge

Widening of the existing bridge is an important part of highway extended projects. How to determine the type of longitudinal joints between the existing bridges and the new ones, and its influence on the structure are critical technologies. Based on the widening project of a PC continuous rigid-frame bridge over the Puyang river which is located between Yuanpu Hangzhou and Wangjiajing Zhuji, this paper calculates the forced state of the structure under the effect of concrete shrinkage and creep, differential settlement of foundation and vehicle loading with establishment of a FEM model, and analyzes the different performance of the extended bridge using in two kinds of connection form, rigid connection and hinged connection; it also compares the dynamic performance of the extended continuous rigid-frame bridge with the unextended one, and considers the seismic performance of the bridge structure with different longitudinal connections. The main conclusions can be drawn as follows:(1)Under the effect of concrete shrinkage and creep, tensile and compressive stresses of connections occurred in longitudinal direction. The maximum lateral tensile stress is gradually increasing while the maximum longitudinal tensile stress shows a trend of decrease over time. Compared with that of hinged connections, the maximum tensile stress of rigid connections is less and its change rate larger.(2)The differential settlement of foundation influences the structure’s loaded performance mainly in lateral direction, and sections of the pier top have the most impact. For the lateral tensile stress of rigid connections is larger than that of hinged connections, controlling its reasonable settlement to prevent longitudinal cracks is necessary.(3)Under the effect of the vehicle loading, hinged connections have less stresses so the stresses curve is more smooth. Rigid connections cause larger tensile stress under wheel loading, so in order to ensure traffic safety, some measures to strengthen the construction need to be taken.(4)The analysis of the dynamic characteristics shows that the whole stiffness of the rigid-connection model is larger than that of hinged-connection model, and it accords with the design demands in that the connection parts have no deformation mutation. The types of connections have a significant impact on the lateral stiffness of the structure, and the lateral displacement of rigid connections is relatively less and the lateral stresses are relatively larger under the seismic action.The above research conclusions have some guidance significances to the design and construction of the extended long-span bridge’s connections.