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<br />
<br />Consequently, they are more dependent on
<br />surface soil conditions than posts or piles and their
<br />performance is greatly affected by erosion and
<br />scour which undermines their stability upon which
<br />the elevated manufactured home is dependent.
<br />The use of a pier system should, therefore, not
<br />be considered in areas where any flood velocity
<br />is anticipated.
<br />Piers can be used in backwater (no-flow) flood
<br />areas to elevate the manufactured home above
<br />the anticipated flood level. Where the required
<br />elevation is less than three feet to the bottom of
<br />the chassis I-beam, a conventional installation can
<br />be used as previously discussed.
<br />Based on an analysis of anticipated loads and
<br />the capacity of various pier designs, Table 4.11
<br />provides pier designs acceptable for elevating a
<br />manufactured home.
<br />
<br />"-min.
<br />
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<br />........
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<br />#5 Dowels
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<br />
<br />UMmin.
<br />
<br />1'-6"
<br />
<br />
<br />3-#4 Reinf.
<br />each woy
<br />
<br />Figure 4.26 Pier Design A
<br />
<br />Based on the pier spacing along the length of
<br />the manufactured home and height of the pier, one
<br />or more acceptable pier designs is available. For
<br />other pier designs or conditions not addressed
<br />herein, Appendix D on design calculations can be
<br />consulted.
<br />Pier Design A, as shown in Figure 4.26, consists
<br />of eight inch by eight inch cast-in-place concrete
<br />with four No. 4 steel reinforcement bars. Pier
<br />Design A is acceptable for the conditions labeled
<br />A as shown in Table 4.11, based on a minimum
<br />concrete strength of 2500 psi.
<br />Pier Design, B, as shown in Figure 4.27, consists
<br />of eight inch by 12 inch concrete masonry units
<br />(CMU) with four NO.4 steel reinforcement bars.
<br />Pier Design B is acceptable for the conditions
<br />labeled A or B as shown in Table 4.11 based on
<br />a minimum CMU strength of 1500 psi.
<br />
<br />12- 4Mmin
<br />
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<br />
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<br />each way
<br />
<br />~ "" '4 l"~ l"j.6. t>
<br />'V' ~... ~, t> .
<br />.0. 4 ('j rj..to. 4
<br />v r;.r;iF"?-l 0 ~'::-b.f.,,"t> v
<br />'6:::::~::::i::~
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<br />
<br />Figure 4.27 Pier Design B
<br />
<br />49
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