Shake Table Test of a Concrete Cable stayed Bridge Subjected to Uniform Seismic Excitation

Abstract:

A 1∶20 scale model of a typical mid span concrete cable stayed bridge was designed, constructed and tested on 4 shake tables in longitudinal and transverse directions, respectively, first with minor excitations of Chi Chi wave and then with site specific artificial wave. The destructive behavior was observed with much severe transverse shaking of site specific artificial wave. The experimental results showed that the bridge responses which were excited by the long period Chi Chi wave were larger under longitudinal earthquake input, but the structure responses which were excited by Chi Chi wave and site specific artificial wave were similar under transverse earthquake input because the two wave spectrum characteristics concerned were basically identical. Under the transverse site specific artificial wave input with PGA approaching 1.3g, the upper beams of the tower were obviously damaged including the fracture of longitudinal reinforcement and concrete spalling in a large area, which formed the plastic hinges between the upper tower column and the tower upper beam, therefore the tower base were effectively protected owing to this weakened framing effect.