Shaking table test of curved bridge under ground motion under different site conditions

To study the effects of different site ground motions on curved bridges, a scale model of a curved bridge with the scale ratio of 1:10 was designed by taking a curved bridge with 5% longitudinal slopes as the research object. Ground motions in different site conditions were selected for shaking table test. The results show that the influence of site conditions on the response of the curved bridge was significant. The structural response increased gradually with the site classification changing from I to IV. Compared to unidirectional input, the structural response under bidirectional input was obviously large. The structural response of the main girder was affected the directions of the excitation. When the bridge was excited by the ground motion in the longitudinal direction, the main girder moved horizontally androtated along the fixed pier simultaneously. When the bridge was excited by the ground motion in the transverse direction, the movement of main girder was mainly translational. The structural response of the curved bridge was related to the bridge arrangement and the direction of the principal seismic. When the curved bridge was parallel to the direction of the principal seismic, the tangential displacement response was remarkable. The radial displacement was more significant when it was perpendicular to the direction of the principal seismic. The smaller the angle between the displacement direction of the pier and the direction of the ground motion excitation was, the greater the displacement response of the pier became. The higher the pier height was, the more obvious the magnification of the displacement of the pier was, and the more sensitive the tangential displacement of the fixed pier was to the seismic response. When the curved bridge was parallel to the direction of the principal seismic in unidirectional input, the bearing of the low pier was easy to fall off. When bidirectional input and the curved bridge were perpendicular to the direction of the principal seismic, the high pier was easy to fall off. Therefore, much attention should be paid to the seismic design and analysis of curved bridges. © 2019, Editorial Board of Journal of Harbin Institute of Technology. All right reserved.