Multidirectional Membrane Reinforcement

Abstract

A method for analyzing local strength of reinforced concrete membranes reinforced with a multidirectional mesh and subjected to known in-plane internal forces is presented. Such structures occur often in practice, and include shear walls, floor diaphragms, folded plates, and shells. The effect of concrete cracking on the response of the shell under proportionately increasing loads is examined. The governing system of equations is derived, and a numerical, iterative procedure is developed to calculate local response at any load stage through ultimate. Gupta's conclusion that up to first yield crack direction remains constant and then rotates is confirmed. It is shown that at yield all bars are in tension, an ultimate ductile strength can be calculated from a simple relation; to obtain a time-history response, the method presented here has to be used. The procedure is illustrated with two numerical examples.