shear capacity of reinforced concrete (RC) members can be successfully
increased using near-surface mounted (NSM) fiber-reinforced polymer (FRP)
reinforcement. Tests on NSM-strengthened beams have shown that failure is
controlled by diagonal tension associated to debonding between the NSM
reinforcement and the concrete substrate. In absence of steel stirrups and/or
when the spacing of the NSM reinforcement is large, debonding involves
separately each of the bars crossed by the critical shear crack (type-I
failure). The presence of steel stirrups, combined with a relatively small
spacing of the reinforcement, may originate a debonding failure mechanism
involving the lateral concrete covers of the steel stirrups (type-II failure).
Thus, an analytical model able to encompass both failure modes must be
developed. This paper extends a previous simplified model to predict the FRP
contribution to the shear capacity when type-I failure occurs. The model,
suitable for immediate design use, assumes a complete redistribution of the
bond stresses along the failure interface at ultimate. Experimental results
from previous test programs are compared to the model predictions.