General Prediction Model of Compressive Strength for Confined Concrete

Abstract

This paper presents the general prediction model of compressive strength which can be applied for concrete confined by any material. Prediction models of confined concrete have been developed at every appearance of new confining material. Confined concrete has steel tube, spiral or hoops and FRP jacket as external confining material. However, steel and FRP have deferent responses to tensile stress. Existing prediction models regard confining stress as a function of steel yielding strength for steel confinement and rupture stress/strain of FRP jacket and predict compressive strength by one variable function of confining stress. The main feature in this general model is the intersecting line between lateral stress and strain relationship of confining material and relationship between axial stress and lateral strain under constant lateral stress, in three-dimensional space among axial stress, lateral stress and lateral strain. Therefore, the prediction model is with lateral strain as the additional variable. Application to concrete which has low compressive strength is also considered. Agreement of predicted and experimental compression strength as well as predicted and experimental failure mode are examined.KeywordsFibre-reinforced polymerConfined concreteCompressive stressLateral confining pressurePrediction model