Experimental and analytical investigation on the use of NSM-BFRP and NSM-GFRP bars in strengthening corrosion-damaged RC slabs

Abstract

This paper presents the results of an experimental and analytical study on the flexural behavior of corrosion–damaged reinforced concrete (RC) slabs strengthened with different near–surface mounted fiber–reinforced polymer (NSM–FRP) bars. An accelerated corrosion technique was used to induce corrosion in the steel reinforcing bars of the tested slabs. The investigated parameters comprised the number of NSM–FRP bars (two and four bars), the type of the NSM–FRP reinforcement (basalt B and glass G bars), and the mass loss in the steel rebars due to corrosion (10 and 20%). The yielding and ultimate capacity of the strengthened slabs was not only restored but surpassed those of the virgin control slab. Slabs strengthened with two and four NSM–BFRP bars showed 32–42% increase in their yielding load and 45–50% in their ultimate loads, respectively, as compared to the unstrengthened corroded slab. Similarly, the strengthened slabs showed 5–50% increase in their ductility index as compared to the virgin slab. The strengthened slabs failed due to the yielding of the steel reinforcing bars followed by compression concrete crushing. ACI–440 formulations reasonably predicted the performance of the strengthened slabs with conservative capacities when ACI strain limit of 0.7 εfu was considered.