Behavior of Deep Beams using Different Concrete Grades

This paper presents the experimental results of the investigation of behavior of simply supported deep beams having layers of concrete of different grades (25 MPa and 50 MPa). The tested beams were loaded with one vertical load at mid span up to failure. All specimens were fabricated and tested at the laboratory of reinforced concrete of Faculty of Engineering, Ain Shams University. The experimental program is carried out using five simply supported deep beams having the same dimensions; specimens with an effective span of 1100 mm, width of 200 mm and a height of 1000 mm, specimens also have the same top, bottom, vertical, and horizontal reinforcement. The experimental studies showed that the failure of tested deep beams was mainly due to diagonal cracks. Casting concrete on different layers causes the first cracks appeared at earlier load than in beam with one grade of concrete. It was also found that the best flexural behavior of deep beams is obtained when the bottom layer is casted using high concrete compressive strength and gives results (deflection, and failure load) close to results of deep beam casted with high compressive strength.