Development of P-M interaction chart for rectangular shear walls as per fundamental principles

Abstract

Shear walls can act as excellent lateral load resisting system in multi-storeyed buildings, because of their high in-plane stiffness and strength. As per IS 13920:2016 reinforced concrete walls which carry lateral forces are termed as special shear wall and should be design accordingly. IS 13920:2016 proposes two closed form equations to calculate moment capacity of slender rectangular RC shear walls, which do not satisfy all the requirements IS456:2000. Equations provided in IS 13920:2016 are based on bilinear stress strain relation of HYSD steel bars. Vertical reinforcements which are distributed along the entire cross section of the wall are considered equivalent to a steel plate having the length of the wall and whose thickness is to be calculated so that the area of the plate is equal to the total area of the vertical reinforcement. Hence, stress blocks of steel along with stress block of concrete have been used to calculate force and moment capacities of the section. Shear wall sections are simultaneously subject to flexure along with axial forces and need to be design by using interaction charts. unfortunately, in our standard some shortcut design methodology has been provided in lieu of interaction charts, and these equations suffer from a number of limitations. In the present paper, a humble effort has been made to propose interaction charts to design using limit state philosophy as per IS 456–2000.