NONLINEAR FINITE ELEMEN ANALYSIS OF HIGH STREGTH REINFORCED CONCRETE SLABS

Abstract

This study describes a three-dimensional material nonlinear finite element model suitable forthe analysis of high strength reinforced concrete slabs under different states of loading. Thetwenty-node isoparametric brick element has been used to model the concrete while reinforcingsteel bars have been idealized as axial members embedded within the brick elements. Thebehavior of concrete in compression is simulated by an elasto-plastic work hardening modelfollowed by a perfectly plastic response, which is terminated at the onset of crushing. Intension, a smeared crack model with fixed orthogonal cracks has been used with the inclusionof models for the retained post-cracking tensile stress and for the reduced shear modulus. Threehigh strength reinforced concrete slabs and one normal strength concrete slab have beenanalyzed in the present study with different boundary conditions and loading arrangements.Parametric studies have been carried out to investigate the effect of some important finiteelement and material parameters. These parameters include the compressive strength ofconcrete, amount of reinforcement and slab thickness. The finite element analysis indicated thatwhen the concrete compressive strength of the slab is increased from (35 MPa) to (80 MPa) anincrease in the ultimate capacity of about (60%) has been achieved. In general good agreementbetween the finite element solutions and the available experimental results have been obtained