Prestressed lightweight concrete slabs strengthened with carbon-fibre-reinforced polymer

The effect of applying carbon-fibre-reinforced polymer sheets together with a prestress force to strengthen lightweight reinforced concrete slabs was investigated experimentally and numerically. As reported in this paper, load–deflection curves, stiffness, energy-absorption capacity and crack width of the prestressed slabs were examined and a detailed numerical model is presented. Strengthening with polymer layers resulted in a larger lever arm, while prestressing slightly reduced the lever arm of the section. The maximum deflection of prestressed slabs was smaller than that of the control specimen due to a small reduction in energy absorption. Using polymer sheets increased both the strength and maximum ultimate deflection simultaneously due to a higher energy-absorption capacity. The formation and propagation of cracks was postponed due to prestressing, so the ultimate crack width was reduced. Owing to the increase in stiffness, the polymer strengthening reduced crack spacing, crack width and crack growth for all strengthened specimens. In addition, a parametric study revealed that the variations in tendon eccentricity had a significant influence on the force–displacement response of slabs, whereas variations in characteristic strength and dilation angle only had a slight effec/t.