Chapter 19 - Yield Line Analysis of Slabs

Abstract

This chapter presents a theory that extends the ultimate load analysis of structures for beams and frames to reinforced concrete slabs. There are two approaches to the calculation of the ultimate load-carrying capacity of a reinforced concrete slab involving yield line theory. One is the energy method, which uses the principle of virtual work, and the other is the equilibrium method, which studies the equilibrium of the various parts of the slab formed by the yield lines. A slab is assumed to collapse at its ultimate load through a system of nearly straight lines that are called yield lines. These yield lines divide the slab into a number of panels, and this pattern of yield lines and panels is termed the collapse mechanism. The panels formed by the supports and yield lines are assumed to be at plane and therefore must possess a geometric compatibility. It is further assumed that the bending moment along all yield lines is constant and equal to the value corresponding to the yielding of the steel reinforcement.