YIELD LINE THEORY OF R. C. SLABS

Abstract

It is a well known fact that behaviour of concrete at early stages of loading may be more or less approximated to be elastic but it does not remain elastic upto failure. The present , esign procedures for the design of T1,,C. Slabs are based on elastic analysis of the slab# The elastic analysis fails to give the collapse load of R.C. Slabs because near the failure concrete and steel both are more near to plastic phase than elastic one. Thus elastic theory cannot give us a true idea of the factor of safety of the structure. Therefore it is more rations . to base the design on ultimate strength of the structure# In this work a review is presented of the method of plastic design for E,C. Slabs as developed by Ingerslev and Johansen; known as "Yield line theory", which deals with the reinforced concrete slabs failing in flexure. The application of theory has been elucidated by analysing various cases with various fracture patterns, Chapter IV also deals with practical design method. A simply supported two way rectangular slab, being of common ocvuurance (since fixed or continuous slab may be transformed to the simply supported one for the purpose of calculations as in section 444 - Case V) is studied in greater details; with special reference to the extent of negative reinforcement. An example has also been solved for the same.