Analysis performance of Confined Concrete Models

Material models play a key role in a realistic prediction of the performance of a structure. Accuracy of various stress-strain relationship models for concrete confined by lateral steel reinforcement in prediction of the moment – curvature response of a section under various loading patterns was investigated. Each confined concrete model was used in the analysis for several loading cases on a circular section keeping all other parameters fixed. Results were compared to each other and also validated against experimental data tested under the analyzed loading cases. In general , the response was controlled more by the steel behavior than concrete , for low axial load levels. The moment was underestimated and the curvature overestimated under a high level of axial load regardless of the model used and there was a better agreement between analysis and test for low level or no axial load cases. For a monotonic curvature with non-proportionally variable axial load, predictions by some recent models had a better agreement with experimental data. Evidently the level of axial load, and in turn the depth of compression zone , is related to the degree of confinement – utilization , and affects the confined concrete behavior . This is rarely addressed by the models.

Keywords:

axial load , confined concrete , material models , moment - curvature