Experimental Study on the Response Characteristics of Typical Beam Bridges to Near-Fault Ground Motions

The design response spectrum in the current bridge seismic design specifications is mainly based on far-fault observation records and cannot accurately reflect the ground motion characteristics and structural seismic response characteristics in the near-fault area. Therefore, the seismic design of bridges in the near-fault area may be unsafe. An experimental study was conducted based on shaking table, in order to study and verify the response characteristics and rules of typical beam bridges under near-field vibrations with the input of both horizontal and vertical ground motion accelerations. The result shows that for a simply supported beam bridge, the biggest feature of the horizontal effect of near-field vibrations is to amplify the displacement of the superstructure and the shear deformation of the supports. The impact on the stress at the pier bottom and the acceleration of the superstructure is less than the impact on the displacement. The main mode of beam bridge and the peak ground motion acceleration range when the bearing enters into stretch state under vertical ground motions are also figured out in the experiment.