McCormac 2008, p. 50. "The term limit state is used to describe a condition at which a structure or part of a structure ceases to perform its intended function. There are two categories of limit states: strength and serviceability." McCormac, Jack C. (2008). Structural Steel Design (4thed.). Upper Saddle River, NJ: Pearson Prentice Hall. ISBN978-0-13-221816-0– via Google Books (preview).