Design for torsion and shear

1 Design for torsion and shear: Torsion is moment act along the longitudinal axis of the beams, two types of torsion exist in structures first primary or equilibrium torsion as shown inFig. (a) and secondary or comabatibilty torsion in Fig.(b) in which moment distribution will occure and reduce the torsion value, torque value depends on the rigidity of the beam shown in (c,d). The design for torsion is based on a thin walled tube (space truss analogy), the beam is idelealized as a thin waaled tube with core concrete cross section in a solid beam neglected as shown in figure below. The torsion resistance is provided primarily by closed stirrups and longitudinal bars located near the surface of the member. The resistance is assumed to be provided by outer skin of the cross section roughly centered on the closed strriups. Both hollow and solid sections are idealized as thin walled tubes both before and after cracking. The figure below shows the difference between shear stress distribution along the section produced from shear force and from the torsion, the critical case is that when addition of the shear stress in the same direction occurs.

Design for torsion and shear

Documents

torsion

beam

torsional strength

reinforced concrete

shear

equilibrium torsion