New Strength Model and Experimental Investigation of FRP Confined Concrete Columns Using CFRP and GFRP Materials

Covering a fiber-reinforced fiber reinforced concrete column (FRP) improves the performance of the column primarily. This paper is intended to investigate the behavior of small FRP concrete columns that are subject to axial pressure loading, in order to study the effect of many parameters on the effectiveness of FRP couplings on circular and square concrete columns. These parameters include the shape of the browser (circular and square), whole core and cavity, square radius of square columns, concrete strength (low strength, normal and high), type of FRP (carbon and glass) and number of FRP (1, 2 and 3) layers. The effective fibrillation failure strain was investigated and the effect of effective lateral occlusion pressure. The results of the test showed that the FRP-coated columns improved significantly the final conditions of both the circular and square samples compared to the unrestricted columns; however, improvement of square samples was not as prominent as improvement in circular samples. The results indicated that many parameters significantly affected the behavior of FRP confined columns. A new model for predicting compressive force and the corresponding strain of FRP is presented. A good relationship is obtained between the proposed equations and the current experimental results.