A new approach to the yield criterion for isotropically reinforced concrete slabs

An expression based upon strain compatibility considerations is formulated for the normal moment of resistance across a yield line. Experiments are described which were designed to test this theory, and the results are shown to be consistent with its requirements. A method of incorporating the expression for normal moment into a generalized yield criterion is presented. The square yield criterion is found to be a lower bound on the yield criterion obtained and is approached as the ratio of crack width to bar diameter increases.