Which of the following design methods of reinforced cement concrete structures is based on the linear elastic theory?
A reinforced concrete structure should be so designed that it fulfills its intended purpose during its intended lifetime with :
(i) Adequate safety, in terms of strength and stability.
(ii) Adequate serviceability in terms of stiffness and durability
(iii) Reasonable economy
The following design methods are used for the design of reinforced concrete structures/elements are :
The Modular Ratio Method or the Working Stress Method (WSM)
The Load Factor Method or the Ultimate Load Method (ULM)
The Limit State Method (LSM)
WORKING STRESS METHOD (WSM):- This is the traditional method of design, used not only for reinforced concrete but also for structural steel and timber. Close to about a hundred years old, the method is based on linear elastic theory or the classical elastic theory.
This method of design was evolved around 1900 and was the first theoretical method accepted by the National Codes of Practice for the design of reinforced concrete sections.
This method ensures adequate safety by suitably restricting the stresses in the materials (i.e. concrete and steel) induced by the expected working loads on the structure. The assumption of linear elastic behavior is considered justifiable since the specified permissible (or allowable) stresses are kept well below the ultimate strength of the material.