Shear strengthening of reinforced concrete beams with near surface mounted steel bars

Abstract

This paper reports on an experimental study examining reinforced concrete beams without stirrups strengthened with Near Surface Mounted (NSM) steel bars. The beams were simply supported and were subjected to four point bending load. Three beams tested were designed as control specimens and the other six beams were strengthened with NSM steel bars. Three ratios of longitudinal reinforcement (1%, 1.4%, and 2.4%) and two types of installation angle (45 and 90 degree) were used as test variables. The test results in terms of graphs of deflection due to shear forces are presented to demonstrate the ability of different longitudinal reinforcement ratios and installation angle to withstand shear forces. The influence of the test variables on the crack patterns was also observed. It was found that NSM steel bars increase the shear strength of reinforced concrete beams without stirrups significantly. However, in the case of higher longitudinal reinforcement ratios the beams failed in brittle mode as indicated by a sudden drop in the shear force-deflection graphs.