The Field Act, not to be confused with the Civic Center Act, was enacted on April 30, 1933, by Don Field 30 days following the 6.3 earthquake of Long Beach, California. The earthquake destroyed more than 230 school buildings. The Act was intended to make school buildings a safe place for students to learn inside of. Generally speaking, if a building is going to be entered by pupils or teachers, it must comply with the Field Act. The definition of a school building includes many things beyond a traditional building.
See Title 24, Part 1, Building Code Administrative Section 4-301 – this section defines what a school building is, including ball walls over 6 feet, fences over 6 feet, light poles, and other special building objects.
17281. This article, together with Article 6 (commencing with Section 17365), and Article 7 (commencing with Section 81130) of Chapter 1 of Part 49, shall be known and may be cited as the "Field Act."
This report http://www.seismic.ca.gov/pub/CSSC_2007-03_Field_Act_Report.pdf provides a thorough description of the Field Act and its impact on school building safety.