Torsional strength and deformation characteristics of HSC deep beams reinforced with cross-inclined stirrups

Abstract

Abstract The findings of this paper provide essential knowledge for the effective and economical design of deep beams subjected to pure torsion. As a result, this paper studies the torsional behavior of nine high-strength concrete (HSC) deep beams reinforced by cross-inclined stirrups. The test parameters comprised stirrup type (conventional stirrups and cross-inclined stirrups), inclination angle (45 and 60 degrees), stirrup spacing (100, 150, and 200 mm), the main longitudinal bars (4∅12 and 4∅18), and the side longitudinal bars (without and 4∅12). Torsional moment capacity, crack pattern, twisting angle, strain on longitudinal and transverse reinforcement, and torsional deformation characteristics in terms of stiffness and ductility were used to evaluate the tested beams’ torsional response. Test results clearly indicated that using the cross-inclined stirrup reinforcement improved the evaluated deep beams with conventional stirrups’ torsional capacity, stiffness, ductility, and overall performance. Reducing stirrup spacing from 200 to 100 mm increased torsional capacity by 49% for conventional stirrups and 65% for cross-inclined stirrups. An ABAQUS three-dimensional finite element model was built to evaluate the model’s ability to replicate the experimental beams’ torsional behavior. A theoretical model for ultimate torque calculation was also created. Compared to experimental findings, numerical and theoretical investigations were satisfactory.