Elastoplastic Confinement Model for Circular Concrete Columns

This paper presents relatively simple, analytically derived curves to model the axial and the lateral stress-strain relations of circular concrete columns. The analytical curves describe the full elastoplastic behavior of the confined concrete column. The solution to the partially confined reinforced concrete column in the elastoplastic range is derived by replacing the discrete lateral reinforcement with an equivalent tube and the Drucker–Prager (DP) yield criterion is applied to represent the concrete behavior in the plastic range. Application of the DP model does not require an iterative procedure in order to solve the problem and thus an explicit solution is obtained. It is shown that the proposed model properly simulates the behavior of reinforced concrete columns partially confined by steel ties and of columns that are fully confined by fiber-reinforced polymer sheets.