Working Stress Method

Working Stress Design

• Traditional method of design

• It is assumed that concrete is elastic

• Steel and Concrete together behaves elastically

• The basis of this method is that the permissible stress for concrete and steel are not 

exceeded in any worst combination of working load

• The sections are designed assuming the materials obey Hooke’s law

Assumptions in Working Stress Method:

• A section which is plane before bending remains plane after bending

• Bond between steel and concrete is perfect within elastic limit of steel

• Tensile strength of concrete is ignored

• Concrete is elastic, i.e. stress in concrete varies linearly from zero at neutral axis 

to a maximum at the extreme fiber

Drawbacks of Working Stress Method:

• Concrete is not elastic

• Difficult to account for shrinkage and creep in WSM