Research Abstract
This paper discusses the flexural strengthening of continuously reinforced concrete (RC) beam constructions in
hogging or sagging regions using near-surface mounted (NSM) technique. The main difficulties in strengthening
RC continuous beams in hogging are the vertical middle column which prevents continuity of the NSM reinforcement
bars and end anchorage of the NSM reinforcement. A test program consisted of seven two-span Tbeams
was used; one control beam, which was used for comparison, four beams were strengthened at the
hogging region, and two beams were strengthened at the sagging regions. Two types of strengthening material
were adopted in this study, carbon fiber reinforced polymers (CFRP) rebars, and high tensile steel bars. An RC
column loaded with a constant load (120 kN) was used as the middle support. The main test parameters were the
type of the reinforcement bars, continuous NSM bars beside the middle column, or NSM bars anchored inside the
middle column, as well as the strengthened region. Besides, the impact of using embedded through-section (ETS)
end anchorage of NSM CFRP bars was investigated as well. The experimental results were evaluated for the
effects of strengthening technique and materials on the load-carrying capacity of beams, deformation, ductility
index, and moment redistribution. The experimental results showed that strengthening with NSM steel bars
could improve the service load carrying capacity by 23–40%, whereas the NSM CFRP rebars improved the
service loads by 33–36%. The ETS end anchorage at the hogging region and the NSM steel bars at the sagging
region helped to achieve the flexural rigidity by a very significant amount relative to the other strengthened
beams and control beam by 270%. The moment redistribution achieved after the beam cracking load until the
failure load varies in accordance with the strengthening region and the strengthening material type.
