Probabilistic assessment on flexural capacity of GFRP-reinforced concrete beams designed by guideline ACI 440.1R-06

The provisions in the guideline ACI 440.1R-06 (call ACI guideline thereafter) on the flexural design of concrete beams reinforced with glass fiber reinforced polymer (GFRP) rods are assessed from the probabilistic point of view by using the Rackwitz–Fiessler method. The assessment reveals that the design provisions in ACI guideline are really conservative. Among all resistance-related random variables, sectional width and height-to-width ratio have put significant influence on average reliability level in either failure mode. GFRP strength does not have any effect on reliability level in concrete crushing mode. Concrete strength shows a negligible effect in the failure mode of GFRP rupture. In the case of GFRP rupture, as the mean-to-nominal ratio of GFRP strength increases, the average reliability index at first increases and then decreases. Design of GFRP-reinforced concrete components subject to aggressive exposure conditions would achieve higher reliability level. As a result of the investigation on the relation between average reliability index and resistance reduction factor, a modified value of 0.81 for the factor is suggested.

Research highlights
► The design provisions in ACI guideline are really conservative.
► Sectional width and height-to-width ratio have significant effects on average reliability level.
► Design of GFRP-reinforced concrete components with aggressive exposures would achieve higher reliability level.
► A modified value of 0.81 for the resistance reduction factor is suggested.