The comparison of working stress design, ultimate strength design and limit design theories of reinforced concrete

Reinforced concrete structures were originally designed on the elastic behavior of the materials by the "Working Stress Design Theory". As reinforced concrete structures became more widely used, another theory based on the inelastic behavior of materials was developed and is commonly known as the “Ultimate Strength Design Theory.” Recently, the attention has been focused on another design theory known as “Limit Design Theory.” This theory is based on the redistribution of moments at high loads.

This thesis presents the comparison of these three theories of reinforced concrete. The members of an interior panel of a continuous framed structure are designed by the working stress design method and then a few members are analyzed by the above three design methods. The comparison has been made on the basis of the live load as a common denominator. The results of the analyses show that the overall increase in live load is 13 percent by ultimate strength analysis and 52 percent by limit design analysis.

This further shows that limit design is a more efficient method for statically indeterminate structures.