ANALYTICAL STUDY ON LONG-TERM DEFLECTIONS OF BEAMS STRENGTHEND BY PRESTRESSED FRP SHEETS

摘要

External bonding of fiber reinforced polymer (FRP) sheets has been proven to be an effective method to strengthen and retrofit deteriorated or damage RC or PC structures. However, the long-term serviceability of such FRP-strengthened beams is still a concern due to lack of long-term performance data especially for prestressed FRP sheets. This study presents a manual method for predicting the short-term and time-dependent deflections for RC beams strengthened by prestressed or non-prestressed FRP sheets. The age-adjusted effective modulus method is used to model the creep behavior in concrete and the relaxation in FRP prestressing sheets. A tension-stiffening model is presented to evaluate the stiffness of the cracked section. The analytical values are compared to the results obtained from a finite element code, and to the experimental results from some existing papers. It is found that the analytical method is in a good agreement with finite element methods.