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Chapter VI: General Design Practices Elevation "t#' Step 5: Design the new fOlmdation walls, For wet f1oodproofing applica- tions, where openings in founda- tion walls are necessary, refer to the section on Wet Floodproofing in this chapter, The design of a new foundation, whether it be a solid or open foundation, is usually governed by the local building codes, These codes will have minimum requirements for foundation wall sizes and reinforcing schemes, including seismic zone considerations, The designer should consult the appropriate code document tables for minimum require- ments for vertical wall or open foundation reinforcement. For new slab applications where the lower level is allowed to flood and the slab is not subj ect to buoyancy pressures, the designer can utilize the Portland Cement Association document Concrete Floors on Ground as a source of information to select appropriate thicknesses and reinforc- ing schemes based upon expected loadings. The slab loadings will vary based upon the overall foundation design and the use of the lower floor, Step 6: Design top-of-wall connections, Top-of-wall connections are critical to avoid pullout of the sole plate, floor diaphragm, andlor sill plate from the ma- sonry foundation. A preliminary size and spacing of anchor bolts is assumed, and uplift, shear, and tension forces are computed and compared against the allowable loads for the selected bolts. Where necessary, adjustments are made to the size and spacing of the anchor bolts to keep the calcu- lated forces below the allowable forces, It is usual to include a factor of safety of 1.3 to respond to flood, wind, and seismic forces, VI - E.42 Engineering Principles and Practices of Retrofitting Flood-Prone Residential Structures January 1995 I I