Abstract
Based on the seismic isolation design concept of functional separation, a seismic isolation system with bearings and braces combination for railway bridge was proposed. The sliding bearings afford the vertical loads, and the self-centering energy dissipation brace (SCED) and buckling restrained brace (BRB) control the horizontal displacement of the beam, so the functional separation was achieved under the combined action. Taking a long-span railway continuous beam-arch bridge as an example, the corresponding analysis model was established to study lateral seismic response and the girder’s displacement pattern of the continuous beam-arch bridge under the earthquake excitations. The seismic response of bridges with different seismic isolation schemes was studied. The result showed that the presence of arch rib in a continuous beam-arch bridge amplifies the transverse displacement response of the girder compared with that in a continuous beam bridge of equal mass. The seismic isolation system with sliding bearings and energy dissipation braces can control the relative displacement between the pier and beam greatly, and the SCED can reduce or even eliminate the residual displacement between pier and beam. Furthermore, under the strong ground motions, the combined use of SCED and BRB can achieve the seismic isolation to the maximum extent when the self-centering force ratio ζ, the ratio of self-centering force to superstructure weight, is 0.074.
Highlights
Based on the seismic isolation design concept of functional separation, a seismic isolation system with bearings and braces combination for railway bridge was proposed. e sliding bearings afford the vertical loads, and the self-centering energy dissipation brace (SCED) and buckling restrained brace (BRB) control the horizontal displacement of the beam, so the functional separation was achieved under the combined action
Taking a long-span railway continuous beam-arch bridge as an example, the corresponding analysis model was established to study lateral seismic response and the girder’s displacement pattern of the continuous beam-arch bridge under the earthquake excitations. e seismic response of bridges with different seismic isolation schemes was studied. e result showed that the presence of arch rib in a continuous beam-arch bridge amplifies the transverse displacement response of the girder compared with that in a continuous beam bridge of equal mass. e seismic isolation system with sliding bearings and energy dissipation braces can control the relative displacement between the pier and beam greatly, and the SCED can reduce or even eliminate the residual displacement between pier and beam
A railway continuous beam-arch bridge was regarded as the proto structure, and the influences of arch ribs on the lateral seismic response and displacement patterns were discussed
Summary
Of 28 mm (V28), and the stirrups have a nominal diameter of 12 mm (V12). e nominal tensile strength of the reinforcing bars is 335 MPa. Ree-dimensional finite element model of the continuous beam-arch bridge was developed in OpenSees (Figure 2). E elastic beam-column element was selected to simulate the girder. Flat Slider Bearing element was selected to simulate the sliding bearing, coulomb friction was adopted in the friction model, and the coulomb friction coefficient was set to 0.02 [40, 41]. Shear keys at the abutments can be simulated by using the simplified elastic-plastic model. Vc and Vs are the concrete and reinforcement contributions to the strength of the shear key, respectively. Fy, are the total area of steel and the yield strength of vertical shear reinforcement, respectively. Steel shear keys at the piers are I-shaped with a yield strength of 235 MPa. e nonlinear beam-column element with a fiber section was used to simulate the I-shaped steel.
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