.MECHANICS AND STRUCTURES fundamental
Safety Factor In applying Equation 10-1, a safety factor or factor of safety is often introduced. A factor of safety makes an allowance for many unknowns related to materials, assembly, or use. Unknowns may be inaccurate estimates of real loads or differences between actual materials and those tested in laboratories. They may be changes in area resulting from corrosion, wear, manufacturing, assembly, or use. They may be irregularities or nonhomogeneity in materials. The unknowns may include suddenly applied, dynamic loads. Technically, a safety factor (SF) refers to the ratio of a failure-producing load to the maximum safe stress a material may carry. The maximum safe stress is often called the allowable stress. Failure may not be by rupture or fracture. A failure could be a change in area or properties of the material that affect the load-carrying capacity and its safety. For structural steel, the allowable stress is derived at the yield point in a stress-strain (load per unit ar...