Vertical seismic response of a box bridge strengthened with posttensioned, prestressed CFRP sheets

Abstract

ABSTRACTIn this paper, a finite element model is developed to analyse the responses of a box bridge to different seismic waves before and after strengthening using posttensioned, prestressed carbon fibre reinforced polymer (CFRP) sheets. The box beam and pier of a four-span continuous box bridge in Tianshui City were strengthened, and the seismic performance was studied. Based on the vertical seismic loads, the dynamic time-history of the entire bridge was calculated, and the effect of the posttensioned prestressed CFRP sheet on the seismic performance of the bridge was examined. The dynamic responses of the box bridge to three waves show that the vertical displacement and acceleration of the sections under the Tianjin wave decreased after their peaks; however, the vertical displacements and accelerations for the El Centro and Lanzhou waves slowly stabilised. Consequently, the Tianjin wave caused more damage to the bridge structure than did the other two waves. The seismic responses of the bridge under the actions of the three waves can be effectively reduced after reinforcement with a posttensioned prestressed CFRP sheet.