Size effect tests on shear failure of interior RC beam-to-column joints under monotonic and cyclic loadings

Abstract

The main objectives of this study are, on one hand to present an experimental campaign on the shear failure behavior of reinforced concrete (RC) beam-to-column joints having different structural sizes, especially full-scale joints, and on the other hand to evaluate the possibility of the existence of size effect on the corresponding nominal shear strength of the RC joints. The test results of geometrically similar interior RC beam-to-column joints with the joint width ranging from 300 mm to 900 mm under both monotonic and cyclic vertical loadings are reported in this study. The effects of stirrup ratio and loading type on the seismic shear failure behavior at the core region of the joints are studied. Moreover, the size effect of the corresponding nominal shear strength of the RC beam-to-column joints is also explored. The experiment results demonstrate that the failure modes of RC beam-to-column joints with different structural sizes are similar. There is a significant size effect, namely, the larger the structural size of the joint is, the smaller the nominal shear strength at the core region of the joint is. Increasing the structural size causes poor ductility capacity, fast degradation of stiffness and more dissipation energy. Moreover, cyclic loading makes the size effect on shear strength of RC joints stronger. The stirrups weaken the size effect on shear failure since the tested shear bearing capacity is mostly carried by the concrete part.