Providing a model for estimating the compressive strength of square and rectangular columns confined with a variety of fibre-reinforced polymer sheets

One of the most common ways of strengthening the columns is the confinement of the reinforced concrete columns. So far, several experiments have been conducted on concrete columns confined with fibre-reinforced polymer sheets and the results show that the use of fibre-reinforced polymer sheets increases the compressive strength of the concrete columns effectively. Different models in order to determine the compressive strength of the fibre-reinforced-polymer-confined concrete columns are provided in the previous researches. In this study, a wide range of experimental data for square and rectangular columns confined with a variety of fibre-reinforced polymer sheets has been collected. In order to increase the accuracy in the existing models, a modified model for predicting the compressive strength of square and rectangular columns confined with different fibre-reinforced sheets has been proposed by using the collected data. In the current study, the fibre-reinforced polymer strain efficiency factor and the section shape factor are composed and considered as a unique factor. Considering the fibre-reinforced polymer hoop strain concentration at the affected area including the corners area and the surrounding area of them, this factor has been adopted as a fibre-reinforced polymer averaged hoop strain factor for the whole circumference of the section. Based on the published experimental data, a comparison between the analytical results obtained with the present model and the results of the other models, shows considerably better results of the proposed model described in this study. Moreover, application of the proposed model for behaviour prediction of concrete-filled fibre-reinforced polymer tubes is evaluated in this study and the results show that the proposed model is more accurate than the other models.