Shortcomings of shear wall design as per IS:13920–2016

Abstract

Reinforced concrete shear walls are almost routinely used in multi-storeyed buildings due to their increased strength, stiffness, and ductility considerations. Shear walls are typically stiffer than regular frame elements. Hence, are subjected to more lateral forces during response to earthquakes. Reinforced concrete walls subjected to compression along with flexure are similar to columns and hence need similar methodology. For a section subjected to compression and flexure, two equilibrium conditions namely force and moment equilibrium equations needs to be solved for any specific load combination. This being a cumbersome and complex proposition, design charts, similar to columns should be used for shear wall design. However, IS 13920:2016 provides closed form expressions for estimation of moment capacity of rectangular RC walls without boundary elements combining these two equilibrium equations by using certain assumption and simplifications which are not conforming to the fundamental philosophies of limit state method as per IS 456–2000. These closed form expressions have several limitations and constraints and the equations are not valid for all the probable positions of neutral axis. In the present work the shortcomings of the codal methodology of shear wall design have been highlighted and method of development of proper design aids for shear wall design have been outlined.