Effect of loading type in concrete deep beam with strut reinforcement

Abstract

Abstract This study examined eight specimens of two groups of deep beam (DB) with the same dimensions and reinforcement quantity, where the first group had four specimens tested under two-point loads and the second group had four specimens tested under one-point load (Ammash HK, AL-Mousawi MM. Experimental investigation of deep beam reinforced with different types of reinforcement. Eng Technol Appl Sci Res. 2021;11(2):7585–90.) where both groups have the same reinforcement and the dimensions and difference between the groups was only the type of load. Digital image correlation technology software was used to verify the results. Upon examining the results, each group had one reference specimen with conventional reinforcement and the other three specimens were with strut reinforcement. It was observed that the strut reinforcement technique was more effective than the conventional reinforcement. This study also found that the load capacity was decreased at two-point loads from one-point load. The results from the present study were compared to those from a prior study (Ammash HK, AL-Mousawi MM. Experimental investigation of deep beam reinforced with different types of reinforcement. Eng Technol Appl Sci Res. 2021;11(2):7585–90.) that only employed a one-point load. The concrete type, its dimensions, and its method of reinforcing were the same as Ammash and AL-Mousawi’s (Experimental investigation of deep beam reinforced with different types of reinforcement. Eng Technol Appl Sci Res. 2021;11(2):7585–90.) study. The maximum load capacity for SC (Reference DB specimen) and S10 (the deep strut beam employed a specimen with 100% reinforcement from the reinforced web) specimens for one-point load were more tolerant to stress than the two-point loads, with 15% for SC and 27% for S10 as both specimens had comparable amounts of reinforcement. When a force is applied that is less than the sum of the two load points, cracks occur in the shear and flexural zones at one load point. We have found that the use of two-point loads leads to a decrease in the maximum load capacity of specimens when compared with a one-point load. It was also noted that cracks are formed in the shear and flexural zones at one-point load when a load less than the two-point load is applied. It was also observed that when two-point loads were applied to a specimen, the displacement was less than half of what it was when tested under a one-point load, and the strain in specimens examined under two-point load was lower than in specimens examined under one point load.