Shear performance of reinforced concrete beams containing stirrups with lower bend defects

Abstract

The reactive expansion caused by alkali-aggregate reactions and severe corrosion in a saline environment may both lead to fracture or complete section loss at the lower bends of stirrups and localized debonding of side-legs nearby. The effects of such bend fracture and the debonded length on the shear performance of a reinforced concrete beam were explored in laboratory experiments and through a finite element simulation. Bend-defects in the stirrups reduced the beam’s shear strength, and the reduction increased with the debonded length. And a parametric analysis indicated that the nominal shear stress carried by the stirrups with a given defect severity increased with section size, and the size effect of shear strength became less significant with increasing defect severity. An approach for predicting the shear strength of such defective beams was proposed based on a transparent and well-understood mechanical and physical model, and published test data confirm its accuracy and safety was confirmed by published test data on 35 beams of various sizes.