Experimental accuracy verification of the common practice analysis of doubly reinforced shallow concrete beams reinforced by steel grade 500

Abstract Beam designers typically use only tension reinforcement. A beam’s moment strength can be increased either by increasing the tension reinforcement area or by increasing the beam depth. However, when architectural or functional constraints limit the beam’s cross-section, a compression reinforcement is added to enhance moment strength. This study aims to assess the validity of the accuracy analysis and design methods for doubly reinforced sections as suggested by various provisions and codes. The study conducted an experimental investigation involving three beams, each with a compression steel to tension steel ratio of 0.2, 0.3, and 1. Furthermore, this study aims to develop a proposed analytical method for the design of doubly reinforced shallow beams utilizing grade 500 steel. The experimental results showed that all beams failed at a compression strain in concrete approximately equal to 0.0015, which is almost one-half of that recommended in most codes. It was clear that using steel grade 500 in doubly reinforced beams of shallow depths requires a high percentage of compression reinforcement to avoid compression-controlled failure, which is uneconomic compared with increasing concrete dimensions. The conventional analysis of such sections is not reasonable; therefore, the proposed analytical method effectively predicted the experimental values of the ultimate load and maximum bending moment of the beam with acceptable accuracy, exhibiting an error of approximately 11%.