Unified strength model based on the Hoek-Brown failure criterion for fibre-reinforced polymer-confined pre-damaged concrete columns with circular and square cross sections

Abstract

Fibre-reinforced polymer (FRP) has the advantages of high strength, light weight, corrosion resistance and convenient construction and is widely used in repairing and strengthening damaged concrete columns. Most of the existing strength models were built by regression analysis of experimental data; however, in this article, a new unified strength model is proposed using the Hoek-Brown failure criterion. To study the strength of FRP-confined damaged and undamaged concrete columns, 900 test data were collected from the published literature and a large database that contains the cross-sectional shape of each specimen, the damage type, the damage level and the FRP-confined stiffness was established. A new strength model using the Hoek-Brown failure criterion was established and is suitable for both circular and square columns that are undamaged, load-damaged and fire-damaged. Based on the database, most of the existing strength models from the published literature and the model proposed in this paper were evaluated. The evaluation shows that the proposed model can predict the compressive strength for FRP-confined pre-damaged and undamaged concrete columns with good accuracy.