Impact behavior of CFRP-strengthened two-way RC slabs with openings: Experimental and numerical study

Reinforced concrete slabs containing openings often exhibit reduced load–displacement capacity, stiffness, energy dissipation, and overall performance under static, seismic, or wind loading. Despite research on composite strengthening techniques, no study has comprehensively examined slabs with openings of varying sizes, locations, and quantities under sudden impact loading, nor assessed the effectiveness of CFRP reinforcement in such scenarios. This study presents an experimental program in which reinforced concrete slabs featuring different opening configurations were retrofitted with carbon fiber–reinforced polymer (CFRP) strips and subjected to sudden dynamic impact using a free-fall drop-weight apparatus. Acceleration responses, impact forces, and maximum and residual displacement-time histories were recorded for the strengthened specimens. Complementary finite-element simulations in ABAQUS were conducted to evaluate the accuracy of the numerical models against the experimental data. Results indicate that CFRP strip reinforcement considerably mitigates the adverse effects of openings under impact loading. Specifically, reinforced slabs with openings achieved peak acceleration values comparable to those of solid slabs, with an average increase of 85% in peak acceleration for the initial drop and 210% for the final drop compared to unstrengthened reference specimen. These findings confirm the efficacy of CFRP retrofitting in restoring and enhancing the impact performance of reinforced concrete slabs containing openings.