Strength design and the design of allowable stress use a combination of many dead or live loads so as to engineer a very safe structure. It additionally uses a variety of resistance factors for each individual structural element so as to calculate precisely, the factor of safety. The values of materials cannot always be repeated. For example, one steel beam will always have a different value of resistance from the other. Though Whittow is a strong proponent for traditional stress design, he prefers using newer methods when required. Allowable stress design was prominent until American Institute of Steel Construction started to update their codes so as to include strength design.
The advantage of Load Resistance Factor Design or strength design is that it returns to the idea of factor of safety according to Tom Whittow, a vice president of computerized structural design in Milwaukee, Wisconsin. He explains that one can adjust the factor of safety simply by varying the materials used, failure types and the mixture of dead and live loads. Calculations in strength design give the engineer the flexibility of adjusting for axial compression, bending, shear and other similar impact loads at a much higher level than required. This gives a higher degree of factor of safety. Fallah Shaikh, a professor of engineering at the University of Wisconsin-Milwaukee, says that to be able to use material values in complete absolute terms is a great advantage in strength design.

Shaikh says that when he uses the strength of materials on its known values, the factor of safety is determinate and very explicit. He adds that the method also considers resistance factors and factored loads together and hence engineers can precisely make combinations on an individual basis and target strength where required. This method also requires detailed calculations which are specific to the factor of each design and construction. These specific numbers provide the design engineer with more flexibility in choices and changes of materials. There is the opportunity for cost saving too if the materials are used economically. Strength design also offers a much better assessment of the structural behavior that can improve safety.