Influence of bend fracture distribution of stirrup on shear behavior of slender RC beams
[Objective]Investigating the influence of alkali-aggregate reaction(AAR)induced fracture at bends of stirrups on the shear performance of reinforced concrete(RC)long beams.[Methods]This study used an artificial method to reproduce the fracture at the bend of stirrup,and investigated the shear behavior of such defected beams through three-point loading.In addition,this study also analytically investigated the shear performance of these test beams by a simulation study using a commercial finite element software Diana.[Results]The results indicated that compared to intact beams,the shear capacity of defective beams with the fracture at lower bends of the stirrup near the supports and complete fracture at lower bends of the stirrup decreased by 10％and 12.6％,respectively.Defective beams with the fracture only at the lower bends of the stirrup near the loading positions experienced a decrease of 0.1％.However,the defective beam,in which stirrups fractured at the bottom bends near the supports and the upper bend near the loading positons decreased by 18.6％.[Conclusions]The fracture at lower bends of the stirrup near the supports weakened the"arch action"and thus reduced the concrete contribution to the shear strength.The fracture at upper bends near the loading points reduced the tensile force of the cross point of stirrup side-legs with the critical shear cracks,and thus reduces the shear contribution from the stirrups through"truss action",while in comparison,the fracture at lower bends of the stirrups near the loading positions has little impact.When the stirrups fractured at the bottom bends near the supports and the upper bend near the loading positons,both the"arch action"and"truss action"were weakened,and thus the shear capacity decreased most significantly.
slender RC beamalkali-aggregate reaction(AAR)finite element analysisshear performanceload-carrying mechanism
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