Experimental investigation on the compressive behaviour of FRP-confined rectangular concrete columns

Abstract

This paper presents a comprehensive experimental study on the behaviour of FRP-confined concrete in square and rectangular columns and focuses on some issues that might be addressed with a view to improving the predictive models. For this purpose, 31 prismatic concrete specimens with a height of 600 mm and low- and medium-strength concrete (20–35 MPa) were tested under centred compression. The parameters studied were the aspect ratio between the sides of the section (1, 1.5 and 2), the radius of curvature of the corners (20, 25 and 30 mm) and the number of carbon FRP layers applied. The experimental results included stress–strain curves of specimens and detailed information about the confined concrete strength and the axial and lateral strain achieved on the FRP jacket during the tests. The stress–strain response and ultimate condition are analysed, showing that FRP jacketing is an efficient technique for increasing the strength and strain capacity, but that confinement efficiency decreases as the aspect ratio of the section increases. In spite of such decrease, significant strength improvement was achieved for low-strength concrete in rectangular sections with aspect ratios of 1.5 (strength gain up to 81%), and even 2 (up to 36%). The axial strength of the tests was compared with the design criteria of four international guidelines, resulting in predictions that did not properly fit for rectangular sections. A predictive equation is proposed to assess the axial compressive strength of the FRP-confined concrete, which includes a better adjustment for the strain efficiency factor and the shape factor for rectangular columns.

Experimental Studies and Application of Fiber-Reinforced Polymers (FRPs) in Civil Infrastructure Systems: A State-of-the-Art Review

“…However, in this study, WDC exposure was reached in 180 days fewer than in the study by Wang et al [24], while both studies reached the same conclusion: WDC exposure significantly reduces the stiffness and bond shear streets, with reductions of 50.1% and 39.7%, respectively, which permits the definition of CFRP fibers to be the best for use in marine exposure environments [21].…”

“…De Diego et al [ 21 ] affirmed that FRP jacketing is an effective technique to increase strength and strain capacity. Their investigation consisted of analyzing the behavior of FRP-confined concrete under an axial load.…”

Predicting Confinement Effect of Carbon Fiber Reinforced Polymers on Strength of Concrete using Metaheuristics-based Artificial Neural Networks

“…The FRP confinement enhances the strength and durability of the concrete [33], [34], [35], [36]. It increases the lateral pressure on the concrete, which reduces its lateral expansion and improves axial strength.…”

Strengthening Existing Concrete Structures with Fibre Reinforced Polymers (FRP) in the New Version of Eurocode 2

“…Failure mode of FRP confined concrete Current international design guidelines provide predictive design equations to calculate the ultimate strength and strain of FRP confined concrete columns subjected to pure axial load, as a function of the confining pressure applied by the FRP jacket. It is known that the confinement of non-circular columns is less efficient than the confinement of circular columns [33][34][35] (see Figure 7a). In a circular cross section, the jacket exerts a uniform confining pressure over the entire perimeter.…”