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<br />Cross Bracing <br />Cross bracing will improve the stability of the elevated foundation against lateral wind loading. The <br />required number and size of cross bracing members is determined as follows: <br />AT/ = [(h)(L)(Wf)]/Cos-): <br />Ft <br /> <br />Where: <br />AT/ = Total net area of cross bracing required (in2) <br /> <br />h = Manufactured home height (ft) <br /> <br />L = Manufactured home length (ft) <br /> <br />Wf = Design wind load (psi) <br /> <br />Cos -}: = Cosine of angle between cross bracing and horizontal beam. <br /> <br />Ft = Allowable working stress in tension of wood (psi) <br /> <br />Subsequent to calculating the minimum net area, the number of vertical members cross braced is <br />divided into AT/ for each member and a size member chosen having at least that cross sectional area. <br />The following design values were used in developing the criteria for Tables 4.18 and 4.19. <br /> <br />h = 9.75 ft. <br /> <br />L = 32, 40, 48, 52, 56, 60, 66, and 72 ft. <br /> <br />Wf = 15 and 25 psf. <br /> <br />-Cos -}: = Vertical member height above grade at 3, 4, 5, 6, 7, 8, and 10 ft. with a 17 ft. <br />space between vertical members under the manufactured home <br /> <br />Ft = 531.3 psi. <br /> <br />End Bracing <br />There is a need to improve the lateral stability of the elevated foundation against lateral wind loading <br />on the end of the manufactured home. Each end is required to be braced and the size of end bracing <br />is determined as follows: <br /> <br />AT/ = [(h)(W)(Wf)]/Cos-): <br />Ft <br /> <br />Where: <br />AT/ = Total net area of end bracing required (in2) <br /> <br />h = Manufactured home height (ft) <br /> <br />W = Manufactured home length (ft) <br /> <br />Wf = Design wind load (psi) <br /> <br />Cos 1: = Cosine of angle between end bracing and the horizontal <br /> <br />Ft = Allowable working stress in tension of wood (psi) <br /> <br />Subsequent to calculating the minimum net area, the value is divided by two to represent the two <br />members under tensile load at the loaded end of the manufactured home and a member size chosen <br />having at least that cross sectional area. <br />The following design values were used in developing the criteria for Table 4.20. <br /> <br />h = 9.75 ft. <br /> <br />W = 12 and 14 ft. <br /> <br />Wi = 15 and 25 psf. <br /> <br />Cos -}: = Vertical member height above grade at 3, 4, 5, 6, 7, 8, and 10 ft. and vertical <br />support spacings of 5, 6, 7, 8, 9, and 10ft. <br /> <br />Ft = 531.3 psi. <br /> <br />94 <br />