Abstract:

One of the most effective methods to reduce the story height is to use reinforced concrete （RC） beam with opening. However, there is a lack of systematic multi-parameter experimental investigations of such beams. In this paper, 20 simply-supported reinforced concrete beams with rectangular openings were tested under concentrated load. Experimental results show that （ 1 ） the beam with rectangular opening is of a reduced shear capacity and special deflection deformation characteristics different from those of common beams; （2） both the strengthening stirrups and the bent-up steel bars at the opening sides improve the shear capacity of the beam; （3） the shear-compression failure can be avoided if the transverse reinforcements and the stirrups of chords are large enough; and （4） the concretes above and below the opening can be considered as an eccentric compressive component and an eccentric tensile one with anti-bending point, respectively. A prediction method of bear capacity of the RC beam with rectangular opening is also proposed in this paper.

Key words: reinforced concrete beam, rectangular opening, mechanical behavior, shear capacity