Effect of cross-section size on the flexural failure behavior of RC cantilever beams under low cyclic and monotonic lateral loadings

The objectives of this study are, on one hand, to present an experimental campaign on the flexural failure behavior of RC beams under both low cyclic and monotonic lateral loadings, and on the other hand, to discover the effect of cross-section size on the global mechanical properties of RC beams. Five groups of geometrically similar RC cantilever beams, with cross-section sizes range from 200 mm to 1000 mm and a shear-span ratio of 4 (length to shear span) were experimentally tested. Moreover, a 3D meso-scale numerical method, which could consider both the heterogeneity of concrete material and the nonlinear interaction between reinforcing bars and surrounding concretes, for the simulation of failure of RC members was developed, and some numerical tests were established based on the experimental campaign. The tested results demonstrate the presence of size effect in flexural failure of RC beams under both low cyclic and monotonic lateral loadings. Specifically, the effects of structural size on the seismic performances of the RC beams, involving the failure pattern, the ductility, the stiffness degradation and the load carrying capacity, were extensively investigated based on the combined experimental and numerical tests. Under cyclic loading, due to the low cyclic fatigue damage behavior and for the fact that failure always takes place in concrete which is a quasi-brittle engineering material, all the tested beams could exhibit a more quasi-brittle failure pattern, and consequently the flexural failure of the beams presents a stronger size effect compared with that under monotonic loading.