NATIONAL ACADEMY OF SCIENCES Washington, D.C. 1974
B. CRITERIA FOR DETERMINING THE NEED FOR EXPANSION JOINTS
The need for thermal expansion joints in buildings may bedetermined initially on an empirical basis. If results are deemed by the designer to be too conservative or if the empirical approach is not sufficiently comprehensive to be applicable to the type ofstructure being investigated, a more precise analysis should be undertaken. In either
case, the following criteria should be utilized in the absence of more rational approaches. 1. Empirical Approach a.For buildings having a beam-and-column or slab-and-column structural frame,* the maximum length of the building** without expansion joints should be determined in accordance with Figure 1 on thebasis of the design temperature change (∆t) in the locality of construction. b. For buildings supported by continuous exterior unreinforced masonry, expansion joints should be placed at intervals notexceeding 200 feet. In addition, ntermediate subjoints should be positioned and spaced in accordance with the recommendations of the Brick Institute of America (BIA) and the National Concrete MasonryAssociation (NCMA).*** *A building should be considered to have a beam-and-column or slab-and-column structural frame even if intermittent interior shear walls or other stiffening elements areincorporated in the frame and even if the frame is supported on an above-grade reinforced concrete continuous perimeter base wall. The provisions of this recommendation do not apply to buildings with fullyexposed exterior frames placed outside the cladding elements. **The maximum diameter or diagonal of a round, elliptical, or closed polygonic building should be considered its maximum dimension. ***At the...