Probabilistic evaluation of concrete beams strengthened with full carbon polymer fiber strip

The probabilistic evaluation of torsional concrete beams retrofitted with full strip carbon fiber reinforced polymer (CFRP) laminate is investigated. The first order-second moment reliability method (FORM) was applied to make a probabilistic assessment on the torsional capacity design by technical guideline in Iran. MPO 345 2006 is the first technical code in Iran for design of concrete members strengthened with CFRP laminate. A parametric study on the effects of influencing factors on average reliability level shows that Load effect ratio and yield strength stirrups are the first two main influencing factors among all design variables. A reliability strengthening ratio is introduced to assess the variation in average reliability index before and after strengthening with different resistance factors. A parametric study on this factor reveals that if the reliability level in strengthened reinforced concrete beams is kept to be consistency with their similar unstrengthened beams, a value of 0.81 could be applied.

Keywords:

probabilistic , reliability indexes , torsion , concrete beams , CFRP laminate