Failure stages in post-tensioned reinforced self-consolidating concrete slab strengthened with CFRP layers

In this study, the performance of prestressed reinforced self-consolidating concrete (SCC) slabs strengthened with carbon fiber-reinforced polymer (CFRP) sheets has been investigated experi-mentally and numerically. Effects of prestressing force and number of CFRP sheets on the force?deflection curve, cracking behavior, and energy absorption have been studied. The increase in the prestressing force increased the flexural strength and reduced the crack width; however, it led to a slight reduction in the energy absorption due to reduced deformation. The strengthening of the slab section with one layer of CFRP enhanced the flexural strength and energy absorption by about 30% and 71%, respectively, and reduced the crack width by 23% over that of the control specimen. Applying two layers of CFRP did not enhance the flexural capacity significantly; however, it prevented the CFRP rupture in the transverse direction. Prestressing force reduced the tensile strains in the whole section; however, CFRP-strengthening reduced the concrete tensile strain at the interface between concrete and CFRP sheet. The CFRP-strengthening technique was more effective than increasing the prestressing force in enhancing the performance of reinforced SCC slabs. Furthermore, the results of the parametric study performed on the numerical model of the slabs showed that increasing the eccentricity ratio increased the load bearing capacity by up to 80%, while the effect of concrete compressive strength and applying more than two CFRP layers was insignificant. The findings of the present research showed that combined application of prestressing and using one layer of CFRP sheet can increase the load bearing capacity and ductility of reinforced SCC slabs significantly. Also, combining the prestressing and CFRP-strengthening techniques delayed the debonding of the CFRP layer from the concrete due to reduced cracking and tensile strain.

Automated summary

The study found that the combined application of prestressing and CFRP sheets significantly increased the load bearing capacity and ductility of reinforced SCC slabs, while also delaying the debonding of the CFRP layer from the concrete.