What Does Factor of Safety Mean?
The factor of safety, or safety factor, describes the load-carrying capacity of a system which exceeds the expected or actual loads. The question the safety factor asks is, "How much more robust is the system than is necessary for the load?"
Safety factors may use detailed analysis since comprehensive testing may be impractical on many projects, such as bridges and buildings.
Trenchlesspedia Explains Factor of Safety
Some safety factors, such as the load on a rope, have been reduced to rules of thumb, informal guidelines for use in the field. These rules of thumb tend to not be as accurate as a detailed situational analysis but may use a larger factor of safety because they are based on experience rather than such an analysis.
The factor of safety equals the yield stress divided by the working stress; that is, the system’s actual strength which, if exceeded, leads to immediate system failure, divided by the stress – or the loads – which the system encounters while working.