Effect of NSM Technique on Moment Redistribution in Top Strengthened RC Continuous Beams.

Abundant research has been presented addressing the strengthening of continuous reinforced concrete (RC) beams depending on the moment-redistribution (MR) effect. Most of the research was backed on either strengthening the bottom surface of the beam or both the top and bottom surfaces. As such, both techniques require full accessibility for the beam bottom surface, which may not be applicable. This paper presents a novel strengthening technique using near-surface mounted steel or fiber-reinforced polymer (FRP) laminates. The present study assesses experimentally/numerically the behavior of RC continuous beams top-strengthened at the hogging regions only. The experimental process includes testing five full-scale RC continuous beams strengthened with either steel plates or carbon-fiber-reinforced polymer (CFRP) laminates. Moreover, the numerical model is developed using a finite element (FE) program and used for parametric investigation to assess the strengthening efficiency under different parameters. Strengthening using glass fiber-reinforced polymer (GFRP) laminates was also investigated in the numerical analysis. Strengthening using steel plates caused up to fifty percent moment redistribution with a significant increase in the load-carrying capacity of the beams. On the other hand, CFRP- and GFRP-strengthened beams showed substantial amounts of moment redistribution without significantly affecting the load-carrying capacity. [ABSTRACT FROM AUTHOR]