Study of Reaction Forces on Mobile Home Foundations Caused by Wind and Flood Loads

摘要

Forces acting on the foundations of mobile homes subjected to wind and flood loads were calculated and are presented in a series of computer - generated charts. The loading conditions considered are the two levels of wind loads presently stipulated in the Federal Mobile Home Construction and Safety Standard, a hurricane windload recommended by the National Bureau of Standards (NBSIR 77 - 1289), buoyancy forces, and drag forces resulting from flood water flow. The calculated forces are compared with present anchoring requirements in ANSI Standard 119.3 (NFPA No. 501 A). It is concluded that diagonal ties are instrumental in resisting wind forces, and that vertical ties are more effective than diagonal ties in resisting flood forces. In addition, the study found that tiedown systems designed for hurricane winds can resist buoyancy forces resulting from differential heads of 6 to 8 inches. If vertical ties are added so that there is an equal number of vertical and diagonal ties, resistance would be increased to 10 to 12 inches of differential head. The prescriptive provisions in the NFPA Standard give adequate resistance to the wind loads in the anchors provide the resistance required of the straps. Increase of the number of vertical ties to equal the number of diagonal ties would provide moderate resistance against flooding. The maximum pressures on pier footings caused by combined dead and wind loads are not likely to exceed the design pressures stipulated in the NFPA standard. List of symbols and conversion units, figures, footnotes, photographs, and six references are included. Calculated strap, anchor, and pier loads are appended. (Author abstract modified).