Effect of the transversal-spacing of stirrup-legs on the behavior and strength of shallow concealed RC beams

Abstract

Purpose Shallow concealed reinforced concrete (RC) beams (wide beams) make parts of a structure and are used in the construction industry, especially in ribbed and waffle slab systems. They are designed based on the requirements and provisions of structural codes of practice, which are applicable for shallow dropped RC beams (narrow beams). The main concern in regard to the behavior of these shallow concealed RC beams is transversal-spacing of stirrup-legs across their width. This paper aims to investigate the transversal-spacing of stirrups-legs (Sw) for two shallow concealed RC beams, namely, WB-SC and WB-EC. Design/methodology/approach The beams are tested under a three point-loading system. Their design has been performed to the SBC304 for beam WB-SC (Saudi Building Code for concrete structures) and comparison to EC2 for beam WB-EC (Eurocode-2 for concrete structures) is addressed in terms of flexural and shear strength design requirements. Experimental behavior and results of both beams are analyzed and conclusions are provided; also, a comparison of these codes is performed. Both beams had dimensions of 3,400 mm length, 700 mm width and 350 mm height. Findings Experimentally, beam WB-SC failed in flexure while beam WB-EC failed shear. The investigation concludes in favor of a safer design for SBC304 Code compared to EC2 Code for designing shallow concealed RC beams. Originality/value This study recommends that the transversal-spacing of stirrups-legs of these beams has an influence on their strength and behavior and should not exceed the lesser of 0.56(d) or 170 mm (6.7 in.).