Abstract
This report is concerned with a material nonlinear analysis of reinforced concrete slabs by the mixed finite element method as an application of the initial stress method, taking advantage of laminated elements. Introduced into this method are (1) the nonlinear stress-strain matrices proposed by Kupfer et al. for biaxial state of stresses and (2) an elasto-plastic stress-strain relationship assumed to hold only within biaxial compressive range. Herein discussions are made on the effects of failure conditions of concrete and on such process of transition of the resulting solution as is idealized by a stress intensity reduction curve taking account of the tension stiffening effect. Subsequently the adequacy of the adopted procedure is well substantiated by the comparison among the present solution, previous solutions by some other workers, and the test results obtained by them in a few and those by the authors in more varied cases of supporting conditions of slabs.
