Grid Size Effects With Smeared Cracking in Finite Element Analysis of Reinforced Concrete

Abstract

The effects of modeling parameters on the response of finite element representations of reinforced concrete members are examined. Convergence of load-deflection curves and cracking patterns is studied. Nonlinear behavior is limited to cracking of the concrete and yielding of the reinforcement. The ''smeared" crack representation is governed by a limiting tensile stress criterion. Concrete is treated as linear elastic in compression. Reinforcement has a bilinear stress-strain curve. Constant strain bar elements and rectangular isoparametric elements model the steel and the concrete, respectively. Analyses are performed for flexural members with span-to-depth ratios of 12-1, 5-l and 2-1, under both a uniformly distributed load and a concentrated load at midspan, using a minimum of three variations in grid refinement. Load-deflection curves exhibit convergence with grid refinement. Concrete tensile s tr eng th has a negligible influence on response for the members studied. Load increment size affects the response only in unstable regions of the load deflection curve and does not affect the stiff ness or the post-yield response.