Evaluating Shear Capacity of Concrete Girders with Deficient Shear Reinforcement

Abstract

This study assesses the suitability of four sectional shear methods for predicting the shear capacity of reinforced concrete members which do not comply with S6-06 Section 14 stirrup spacing and area requirements. The results of the evaluations indicate that the sectional shear provisions in S6-06, AASHTO LRFD-05 and software Response 2000 appropriately account for variations in stirrup spacing and area detailing, and present with good agreement between predicted and tested shear capacities for member with deficient shear reinforcement. However, shear capacities calculated using ACI 318-08 do not agree well with tested capacities for members with less than minimum stirrups. Two modified shear methods are proposed, which revise the diagonal crack spacing and concrete contribution area assumed by S6-06. The modified shear methods improve predictions of shear capacity relative to predictions calculated using S6-06 and eliminate the issue of non-convergent shear capacity predictions which can result from evaluation using S6-06.