Seismic Behavior of Continuous Rigid-Frame Box Girder Bridges: A Comparative Study of Different Web Configurations

To support the seismic optimization of long-span bridges in regions of high seismicity, this study evaluates the seismic performance of continuous rigid-frame box-girder bridges with different web configurations. A continuous box-girder bridge with corrugated steel webs (CSWBGB) having a main span of 105 m was analyzed and compared with two control models: a continuous box-girder bridge with flat steel webs (FSWBGB) and a conventional prestressed concrete box-girder bridge (PCBGB). Finite element models of the three web types were developed using MIDAS/Civil, and seismic responses were evaluated using the response spectrum method with geometric nonlinearity incorporated; the analyses were conducted under E1 and E2 ground motion intensities (corresponding to a 63% probability of exceedance in 100 years and a 2% probability in 50 years, respectively, as specified in the Chinese seismic design code). Displacement, axial force, and shear force responses were systematically compared among the three configurations. The results show markedly different seismic responses despite the bridges having similar fundamental frequencies. In the longitudinal direction under seismic excitation, the CSWBGB exhibited larger axial displacement than the FSWBGB, yet its peak axial force and shear force decreased by 13% and 18%, respectively, indicating that the greater axial deformation helps relieve internal force demands. Under transverse E1 seismic action, the CSWBGB displayed smaller lateral displacements than both the FSWBGB and the PCBGB. Compared with the CSWBGB, the PCBGB experienced an 11% larger longitudinal displacement and a 43% higher peak axial force, reflecting its relatively limited seismic performance. These findings demonstrate that the CSWBGB not only provides lighter self-weight than the PCBGB but also offers enhanced transverse stiffness, which results in smaller lateral displacements and lower peak shear forces—thus achieving an optimal balance between lightweight design and structural strength. Although the CSWBGB shows strong potential for practical application, its longitudinal displacement response should be carefully controlled in design.