GFRP Plates for the seismic upgrading of reinforced concrete members with deficiencies in shear and rebar cut-off

摘要

In this study, a seismic assessment using traditional RC analytical model is proposed to provide a simple evaluation on the seismic performance of flanged beams with longitudinal rebar curtailment. The analytical model constructed adopts the skill of RC sectional analysis, shear strength evaluation by shear degradation model, and variable-angle truss model for prediction of angle of concrete diagonal cracks. Analytical results show that reinforced concrete beams in buildings built prior to the mid 1970s may have design deficiencies in rebar curtailment and require retrofitting if they are to survive a strong seismic event without collapse. The deficiency will cause a brittle failure occurred in the vicinity of the beam bar cut-off point instead of the desired plastic hinge developed at beam ends. According to the assessment on the retrofitted beam, the presence of FRP plates can successfully correct the bar curtailment deficiencies and achieve rotation levels greater than those expected to be imposed during an earthquake.