Behavior of reinforced concrete stair slabs strengthened with steel plates and near surface mounted steel bars

The bends in Reinforced Concrete Stair Slabs (RCSS) subjected to opening moments may be damaged due to improper detailing of tensile reinforcement or construction errors. The damaged bends in RCSS need to be strengthened to restore their flexural strengths. However, there are very limited investigations into the behavior of strengthened RCSS. This paper reports experimental and simulation works on the structural behavior of RCSS strengthened with externally bonded steel plates and near surface mounted steel bars. The test program and results of six full-scale strengthened RCSS loaded to failure are described in detail. A finite element model is developed using ABAQUS to simulate the experimentally measured responses of strengthened RCSS. It is shown that the utilized strengthening techniques significantly improve the cracking load, ultimate load, and energy absorption capacity of RCSS. There is a good agreement between computer simulations and experimental results, suggesting that the model of nonlinear inelastic analysis can be used with confidence to conduct further parametric studies.