NONLINEAR ISOPARAMETRIC FINITE-STRIP METHOD

Based on an extension of a previously reported technique regarding the linear elastic analysis employing isoparametric finite-strip elements , a nonlinear model for analysing certain plane-strain problems associ ated with concrete structural forms is proposed, The newly developed m odel employs a previously reported concrete failure criterion in conju nction with a newly developed set of constitutive equations for plane- strain state of stresses in plain concrete up to failure. The reported finite-strip elements are of isoparametric type with two or three cor ners, The new formulations can, unlike traditional finite-strip techni ques, cater for curved boundaries and enable one to analyse certain st ructures in which (although the geometry is still fairly simple) the g eometrical form need not necessarily be uniformly constant along, say, the longitudinal direction of the finite-strip elements, As discussed elsewhere, unlike the traditional finite-strip techniques, the propos ed formulations can handle various boundary conditions different from the simply supported case, with minimal effort. Numerical results are presented as regards the patterns of various stresses within the body of a simple gravity dam and the cylinder used in the classical Brazili an cylinder splitting test when subjected to external loads up to tota l failure, In particular, encouraging correlations are found between c ertain previously reported nonlinear results based on the finite-eleme nt technique and the data from the present formulations as regards the behaviour of the cylinder in the Brazilian indirect test for estimati ng concrete tensile strength.