Abstract
The use of carbon fiber reinforced polymer (CFRP) as an externally bonded reinforcement (EBR) for the strengthening of reinforced concrete (RC) structures loaded by a blast wave is confirmed as an efficient solution. This observation is complementary to other advantages of CFRP such as high tensile strength, light weight and durability. This paper discusses the behavior of CFRP as EBR in the event that two successive independent blast loads are applied on the same target. The main problems are the lack of knowledge regarding the failure modes of the CFRP strips under high strain rate and the blast response of the retrofitted structures when total debonding of the CFRP strips occurs. Four simply supported slabs with different EBR but with the same bond contact surface are tested using an explosive driven shock tube (EDST) to generate the blast wave. Digital image correlation (DIC) is used to measure the strain evolution in the concrete and the CFRP strips during the first explosion. The results show that for the first explosion, EBR increases the flexural strength and stiffness of the RC slabs. In the second explosion, total debonding of the CFRP strips occurs which initiates from the midspan of the slabs towards the supports. When the total debonding of the CFRP strips occurs, the strain distribution in the steel rebars are the same for all slabs regardless of the quantity of applied EBR.
Highlights
Carbon fiber reinforced polymer (CFRP) is used in diverse strengthening applications such as flexural and shear retrofitting of reinforced concrete (RC) beams, slabs, walls and columns
This paper presents an experimental analysis of four supported RC slabs strengthened with carbon fiber reinforced polymer (CFRP) strips under two independent explosions applied to the same target and where total debonding of the CFRP strips occurs
The recorded images show that the total debonding of the CFRP strips occurs at 5 ms after the explosion for all the retrofitted RC slabs and the RC slabs reach the maximum deflection after 27 ms
Summary
Carbon fiber reinforced polymer (CFRP) is used in diverse strengthening applications such as flexural and shear retrofitting of reinforced concrete (RC) beams, slabs, walls and columns. The blast response of CFRP strengthened RC slabs under two independent explosions has not yet been investigated because of the lack of knowledge regarding the failure modes of the CFRP under high strain rate and the blast response of the retrofitted structures when the debonding of the CFRP strips occurs. This paper presents an experimental analysis of four supported RC slabs strengthened with CFRP strips under two independent explosions applied to the same target and where total debonding of the CFRP strips occurs. The primary objectives of this paper are to study the evolution of the strain in the steel reinforcement and CFRP strips during the first explosion and to investigate the effect of the blast wave on the debonding of the CFRP strips due to the propagation of the stresses through the materials during the second explosion. The reflected pressures, maximum deflection and the residual deflection are measured at Proceedings. 2018, 2, 436; doi:10.3390/ICEM18-05317 www.mdpi.com/journal/proceedings
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