This method is also called a modular ratio method where it is assumed that the steel and concrete act together elastically where their stresses are directly proportional to the strain. In working stress design, the design strength is calculated such that the stress in the material is restrained to its yield point, under which the material follows Hooke's law, and hence the term "elastic" is used. In this method stress in  steel and concrete are calculated on basis of the elastic behavioral of the composite section.