Influence of the Boundary Conditions of Simply Supported Beam Bridge with Different Spans on the Seismic Design of Continuous Beam Bridge System

The boundary conditions of simply supported beam bridges with different spans affect the calculation accuracy of continuous beam bridges. A (48 + 80 + 48) m prestressed concrete continuous beam bridge is selected as the analysis object to improve efficiency while ensuring accuracy. The influence of the different boundary conditions on the seismic response of the continuous beam bridge system is studied. Firstly, SAP2000 software is used to establish the finite element analysis model of the system with different boundary conditions. Then, dynamic characteristic calculations and nonlinear time-history calculations are carried out. Finally, the results obtained under the different boundary conditions are compared. The results show that the system’s natural period under different boundary conditions is the same and other periods increase with an increase in the span number of boundary conditions. The different boundary conditions change the order of vibration modes of the system. The system’s track irregularity is mainly longwave irregularities. The results tend to be stable with the increase of the span number of boundary conditions. When the span number reaches 3, the results are stable, and the errors are less than 5%. We suggest taking the three spans simply supported beam bridge as the boundary condition of the continuous beam bridge system in the finite element model to ensure accuracy and efficiency.