Analysis of reinforced concrete beams without shear reinforcement using non-local microplane model

Abstract

The shear resistance of reinforced concrete beams without shear reinforcement is studied using the non-local microplane model and plane stress finite elements. The main objective of the present work is the study of the size effect. Calculated failure loads for geometrically similar specimens of four different sizes are compared with test data and the recently proposed size effect law. Results of the analysis as well as test results exhibit significant size effect. Observed failure is of the brittle type and is due to failure in tension-compression. Further studies with variations of the mesh size and load path demonstrated that results of the calculations using a non-local continuum are not influenced by the above parameters. However, the calculated failure loads depend on the characteristic length over which the strains are measured. In contrast to that, the calculated failure loads are inobjective when a local continuum is used and depend on mesh size, load path and convergence criteria. This is due to the stability of the numerical analysis, which may lead to an overriding of the critical failure mode and activating to a more stable one. In order to correctly predict failure load using local analysis and crack band approach it is necessary to check the stability of the numerical procedure.