Abstract
Rubber isolation bearings have been proven to be effective in reducing the seismic damage of bridges. Due to the different characteristics of isolation bearings, the mechanical properties of bridges with different combinations of rubber bearings are complex under the action of earthquakes. This paper focuses on the application of combinations of rubber isolation bearings on seismic performance of continuous beam bridges with T‐beams. The seismic performances of continuous beam bridges with different combinations of rubber isolation bearings, pier height, and span length were studied by the dynamic time history analysis method. It was found that the bridges with natural rubber bearings (NRBs) have the largest seismic responses compared to the other types of bearings. The continuous beam bridge with isolation bearings, such as lead rubber bearings (LRBs) and high damping rubber bearings (HDRBs), has approximately 20%∼30% smaller seismic response than that with NRBs under the action of earthquakes due to the hysteretic energy of the bearings, indicating that the isolation bearings improve the seismic performance of the bridge. The continuous beam bridges with both NRBs and LRBs or NRBs and HDRBs have larger seismic response of the piers than those with a single type of isolation bearings (LRBs or HDRBs) but smaller seismic response of the piers than those with only NRBs. For a continuous beam bridge with shorter span and lower pier, it is not economical to use LRBs or HDRBs underneath every single girder, but it is more reasonable to use cheaper NRBs underneath some girders. The larger difference in stiffness of the bearings between the side and middle piers leads to the more unbalanced seismic response of each pier of the bridge structure. The results also show that with increasing pier height and span length, the difference in the seismic response value between the cases gradually increases.
Highlights
Among the seismic performance of a continuous beam bridge, traffic safety is of great concern [1, 2]
Numerous studies have proved the efficiency of rubber bearings in reducing the seismic-induced forces of bridge systems [9, 10]. e common types of rubber isolation bearings include low damping natural rubber bearings (LDRs) [1], natural rubber bearings (NRBs) [3, 6], lead rubber bearings (LRBs) [7], and high damping rubber bearings (HDRBs) [2, 8]
The seismic performance of different combinations of rubber isolation bearings for the continuous beam bridges with different pier heights and span lengths under the action of small and large earthquakes was studied. e seismic effects of the different combinations of rubber bearings on the displacement, bending moment of pier, and girder displacement of the bridge under the action of earthquakes were analyzed. e main conclusions are as follows: (1) Due to the nonlinear horizontal stiffness of LRBs and HDRBs, it was proved that the cases in which the bridge uses LRBs and HDRBs were more effective than cases with NRBs in reducing the seismic response of the continuous bridges with T-beams under the action of earthquakes
Summary
Among the seismic performance of a continuous beam bridge, traffic safety is of great concern [1, 2]. The continuous beam bridge with a combination of different bearings has more complicated response to earthquakes because (1) LRBs and HDRBs have nonlinear horizontal stiffness, quite different from NRBs especially at high shear strain amplitudes, and (2) some factors, such as pier height and span length, influence the seismic performance of the bridges [24,25,26]. The seismic performance of continuous beam bridges with combinations of different rubber bearings, such as a combination of NRBs, LRBs, HDRBs, NRBs, and LRBs, and a combination of NRBs and HDRBs, were studied; the bridges with such combinations were compared to the bridges without bearings; the influence of bearing combination, pier height, and span length on the seismic response, including the displacement and energy dissipation of bearings, the displacement of the girder, the displacement of the top of the piers, and the bending moment and shearing force of the bottom of the piers, were discussed. The seismic performance of continuous beam bridges with combinations of different rubber bearings, such as a combination of NRBs, LRBs, HDRBs, NRBs, and LRBs, and a combination of NRBs and HDRBs, were studied; the bridges with such combinations were compared to the bridges without bearings; the influence of bearing combination, pier height, and span length on the seismic response, including the displacement and energy dissipation of bearings, the displacement of the girder, the displacement of the top of the piers, and the bending moment and shearing force of the bottom of the piers, were discussed. e isolation design method for the continuous beam bridges with T-beams was provided; the effects of different combinations of rubber bearings on the mechanical performance of the bridges were studied in order to further understand the optimal configuration of different pier heights and span lengths and provide rational suggestions for selection of bearings for the continuous bridges with T-beams
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