Post-failure Analysis of plain Concrete Structures by a Plastic-Damage Model

Employing a plastic-damage model implemented for 3-D stress space in a special finite element program called SNACS, we examine the post-failure response of plain concrete structures. The plastic-damage model originally proposed by Lee and Fenves is based on a nonlinear fracture mechanics crack propagation criterion. Nonlinear structural problems in which material softening and localization occur constitute a severe challenge to solution algorithms which are based on using an incremental procedure with iterations and suitable constraints. First, the basic concepts of the model along with its computational procedure for stress updating are introduced. Then, the solution algorithms implemented for direct and indirect displacement controls as the two most common approaches in post-failure analyses are summarized. Finally, numerical solutions compared to the available experiment for two plain concrete beams are given to illustrate the ability of the model in capturing post-faluire responses of concrete structures.