Approximate analyses of reinforced concrete slabs

Procedures are investigated by which nonlinear finite element shell analysi s algorithms can be simplified to provide more cost effective approximate a nalyses of orthogonally-reinforced concrete flat plate structures. Two alte rnative effective stiffness formulations, and an unbalanced force formulati on, are described. These are then implemented into a nonlinear shell analys is algorithm. Nonlinear geometry, three-dimensional layered stress analyses , and other general formulations are bypassed to reduce the computational b urden. In application to standard patch test problems, these simplified app roximate analysis procedures are shown to provide reasonable accuracy while significantly reducing the computational effort. Corroboration studies usi ng various simple and complex test specimens provide an indication of the r elative accuracy of the constitutive models utilized. The studies also poin t to the limitations of the approximate formulations, and identify situatio ns where one should revert back to full nonlinear shell analyses.