BEHAVIOR OF R.C. DEEP BEAMS UNDER TORSION LOADS

Abstract

Deep beams exist in many reinforced concrete structures as tanks,dewellings and office building...etc. Most codes study deep beams under flexural and shear loads only but do not say anything about deep beams under , torsion load,however behavior of deep beams differ than that of shallow beams. The thesis deals with the study of the general deformational behavior of R. C. deep beams with different ratio of vertical stirrups , longitudinal steel , and concrete strength, under torsion load , from zero up to failure load. The experimental phase , contains the results of the tests conducted on six scaled direct models of R.C. deep beams under pure torsion load. All beams have the same dimensions . The difference among the six specimens were the ratio of, vertical stirrups, longitudinal steel and, concrete strength. In the theoretical phase ,these six R.C. deep beams were analyzed using the finite elements method , taking into consideration the nonlinear stress-strain curve of concrete and steel ,as well as, bond slippage between steel and concrete. The results of the experimental work and theoretical analysis showed that, the concrete strength has a significant effect on both cracking and ultimate torques, but the value of longitudinal steel and vertical stirrups have a slight effect on cracking torque, and have a significant effect on ultimate torque. Moreover the effect of the vertical stirrups is more than the effect of longitudinal steel on the ultimate torque. Key" Words : Deep beams. Vertical stirrups. Longitudinal steel. Concrete strength. Torsion load. Finite element. Material nonlinearity. Bond slippage.