Accuracy and Improvements for Variable and Constant Confinement Concrete Models

Abstract

A series of experiments were conducted on the performance of concrete under varying levels of passive confinement. Glass and carbon fiber reinforced polymers, and steel plate were used to provide confinement. The research presented compares the measured performance of the jacketed systems with current predictor models and finite element estimations. Two categories of predictor models are examined: Constant Confinement (CC) and Variable Confinement (VC). The CC model assumes that the confining pressure provided by the jacket is active and constant over the load history. VC model assumes that the confinement passively increases as lateral dilation occurs. The research shows that VC models provide improved accuracy over CC models in predicting the stress strain response of confined concrete. Use of multi-linear relationships between axial and transverse strain combined with stress-strain relationships previously developed provide a comprehensive method of estimation. The limitations of these methods are clearly illustrated through examples.