RELIABILITY ASSESSMENT OF CFRP-STRENGTHENED FLEXURALRC BEAMS DESIGNED BY NORTH AMERICAN GUIDELINES

摘要

The design provisions on flexural capacity of CFRP-strengthened RC beams in guidelinesrnACI 440.2R-02 (hereafter called ACI guideline) and ISIS design manual No.4 (hereafterrncalled ISIS guideline) were assessed from the probabilistic point of view by thernRackwitz–Fiessler method combined with the Monte Carlo sampling procedure. The effectsrnof some influencing factors, i.e. load effect ratio, design variables associated with flexuralrnresistance and reduction factors on reliability level were also studied. The assessmentrnindicates that the provisions in both guidelines are rather conservative, with averagernreliability indexes of 4.40 and 4.74 for ACI guideline and ISIS guidelines, respectively. Loadrneffect ratio has put most significant effect on reliability index in both guidelines,rnaccompanied by concrete strength, CFRP strength and CFRP reinforcement ratio. Concreternstrength plays a major role in the mean value and the standard deviation of sectionalrnresistance in both design guidelines. The relationships between reduction factors, i.e. thernresistance reduction factor in ACI guideline and the strength reduction factor of CFRP inrnISIS guideline, and average reliability index are basically linear. Those reduction factorsrnshow limited influence on reliability level.