Shear behavior of RC beams reinforced with internal trussed steel strips at shear span zone

This paper presents an experimental study on the shear performance of reinforced concrete (RC) beams provided with pre-prepared steel trusses in the shear span zone. Those steel trusses were assembled using electrical welding for steel strips of 2 mm thickness. For comparison purpose, corresponding steel trusses were assembled from equivalent rounded steel bars and used to reinforce the shear span zone of corresponding reinforced concrete beams, and then the shear behavior of beams reinforced with either trussed strips or trussed bars was compared. Accordingly, an experimental program consisted of fifteen reinforced concrete beams included one control beam have been prepared where the shear span-to-depth ratio was the same for all beams (2.3). Experimental test results showed that the beams reinforced with trussed steel strips showed better shear performance from the viewpoint of both the ultimate capacity and the developed major shear crack width compared with those of the beams reinforced with equivalent trussed bars. That is because the internal trussed strips have higher surface area than that of the equivalent rounded bars, which enabled the reinforced beam to maintain the confinement of the concrete core inside the section thus decreased the major shear crack width and increased the ultimate strength of reinforced concrete beam. Consequently, the ultimate capacity for reinforced concrete beams reinforced with internal trussed strips was higher than the corresponding capacity of beams reinforced with equivalent trussed bars by an average value of about 16%. Besides, the internal steel strips hindered the appearance of shear cracks and decreased the major shear crack width compared to the case of using equivalent rounded bars. Moreover, the experimental findings showed comparable results against the available analytical models from the viewpoints of ultimate shear capacity and maximum shear crack width.