The various shear-transfer actions due to: aggregate interlock effect, dowel action of the flexural
reinforcement, the uncracked concrete in the compressive zone and the direct strut action for the point
load close to the support, may provide different crack pattern in the shear span of the concrete beams
without stirrups. The aim of this paper is to investigate the shear failure mechanisms in T-shape, single
span and simply supported beams exclusively reinforced with longitudinal glass fiber reinforced polymer
(GFRP) bars. The research of concrete beams flexurally reinforced with GFRP bars without stirrups
indicated the possibility of occurring, besides the conventional shear-compression failure mode, another
type of failure governed by the loss of bond between the ordinary reinforcement and concrete. Usually
the critical shear crack in RC beams without stirrups develops through the theoretical compression strut
preventing a direct transfer of the shear force to the support. The main parameter affecting the crack
pattern and the shear strength of the beams is the shear span to depth ratio. However, the test results
presented in this paper showed the formation of an arching effect due to the bond losing between the
GFRP flexural reinforcement and concrete. This failure mode revealed unexpected critical crack pattern
and failure mode. Digital image correlation (DIC) technique was used to better capture and analyse the
cracking process up to the formation of the shear failure crac
