Evaluation of structural-concrete design-concepts based on finite-element analysis

Finite element analysis incorporating a brittle constitutive model of concrete is used to investigate the validity of the concepts which underlie structural concrete design. It is shown that ignoring fundamental concepts forming the basis of current code provisions – such as, for example, the concepts of “aggregate interlock” and “dowel action” through which cracked concrete is considered to contribute significantly to shear resistance – does not impair the ability of the analysis to yield predictions of structural behaviour which correlates closely with experimental values. For the structural forms investigated, it is found that designing to current codes leads to unsafe solutions, since the analysis predicts premature brittle shear, instead of the intended ductile flexural, failure. On the other hand, designing to the concept of the “compressive force path” which allows for the brittle nature of concrete was found to achieve the design objectives for safety and adequate ductility.