Nonlinear Flexural Response of Continuous Concrete Slab Strips Strengthened with Near Surface-Mounted Composites

This paper aims to study the nonlinear flexural response of continuous RC slab strips strengthened with near surface-mounted (NSM) composite reinforcement in either the sagging or the hogging region. The study comprised experimental testing and three-dimensional finite-element (FE) modeling of eight two-span RC slab strips, 400×125×3,800 mm each. The amount of internal steel in the strengthened regions was approximately 30% of that of the unstrengthened regions. Flexural strengthening with NSM composites improved the stiffness and load capacity of continuous RC slab strips with no or insignificant reduction in the deflection at ultimate load. The gain in the load capacity due to strengthening was more pronounced for the slab strips strengthened in the sagging regions. Flexural strengthening reduced the moment redistribution ratio of the slab strips. The ratio further decreased by increasing the axial stiffness of the NSM composite reinforcement in the strengthened regions. The developed FE models provided more than reasonable prediction of the ultimate load by simulating the nonlinear structural behavior of the tested slab strips with good accuracy and predicting strain data not captured experimentally in some specimens. The validated FE models are considered a valuable and reliable alternative to the laboratory testing, which is costly, labor-intensive, and time-consuming.