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Manufactured Homes - Probability of Failure and the Need for Better Windstorm Protection Through Improved Anchoring Systems.


pdf icon Manufactured Homes - Probability of Failure and the Need for Better Windstorm Protection Through Improved Anchoring Systems. (2237 K)
Marshall, R. D.

NISTIR 5370; 54 p. November 1994.

Available from:

National Technical Information Service
Order number: PB95-143129

Keywords:

building technology; codes; standards; hurricanes; manufactured housing; mobile homes; natural disasters; soil anchors; structural engineering; wind damage; wind engineering; wind loads; windstorm protection

Abstract:

Probabilities of failure are estimated for structures designed in accordance with the wind load provisions of the Manufactured Home Construction and Safety Standards (MHCSS) that were in effect at the time of Hurricane Andrew (1992) and for structures designed in accordance with the wind load provisions of ASCE 7-88 (Minimum Design Loads for Buildings and Other Structures). It is concluded that for a 10-yr exposure the probability of structural failure in a hurricane-prone area such as Dade County, Florida, using the MHCSS wind load criteria is approximately 10 times that determined using the wind load requirements of ASCE 7-88. This same ratio holds for an extra-tropical wind climate such as that of Omaha, Nebraska. For Tucson, Arizona, this ratio is approximately 5. Test data for various components of traditional manufactured home anchoring systems are examined and it is concluded that the load capacity of these systems is substantially less than the load capacities implied by the MHCSS and by current standards covering the installation of manufactured homes. It is recommended that traditional anchoring systems that utilize allow soil anchors be designed on the basis of factored loads and that preloading be made an integral part of the installation process. A new approach to providing windstorm protection for manufactured homes located in hurricane-prone regions needs to be developed.