This Digest provides procedures for the selection of steel joists and Joist Girders that are required to meet the stability requirements resulting from the accumulation of water on a roof system, i.e., ponding. The digest provides background information and discussion of the requirements for ponding calculations contained in ASCE 7, IBC and FM Global, and identifies the main factors influencing the ponding stability of open-web steel joist roofs. The limitations of the method of ponding analysis given in Appendix 2 of the AISC Specification are also discussed. The theory and assumptions used in the SJI ponding tool are provided along with several examples checking the stability of roof systems using the SJI ponding tool and the AISC ponding provisions. The benefits of camber and pitch of joists in reducing the effects of ponding are also discussed.
The hardcopy version of this publication will be available for purchase February 20, 2018.
Published February 2018