Shells for Standard Floor and Roof Elements

On reviewing the state of technology of the design, analysis, and construction of shallow funicular reinforced concrete shells, it is apparent that: (1) the possible modes of failure are known and understood; (2) approximate relations are available that permit reasonable designs; (3) simple methods are available for their construction; (4) at this time they are economical only for spans greater than 50 ft (15.10 m); (5) they should not be used for applications involving dynamic loading until further research is conducted; (6) the finite element method provides an ideal analysis tool for assuring adequate design of shallow shells, although improvement of existing codes is needed to permit accurate definition of all potential failure modes.