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` SFGNET STL Project No. 0010771 <br /> v�sdng Labs Page 9 <br /> The total settlement is not expected to exceed one inch. Differential settlement should be less than one- <br /> half inch. Most of the settlement is expected to occur during construction as the loads are applied. <br /> However, additional post-construction settlement may occur if the foundation soils are flooded or <br /> saturated. <br /> The footing excavations should not be allowed to dry out any time prior to pouring concrete. It is <br /> recommended that footings be reinforced by at least one #4 reinforcing bar in both top and bottom. <br /> Resistance to lateral footing displacement can be computed using an allowable friction factor of 0.4 <br /> acting between the base of foundations and the supporting subgrade. Lateral resistance for footings can <br /> alternatively be developed using an allowable equivalent fluid passive pressure of 350 pounds per cubic <br /> foot acting against the appropriate vertical footing faces. The frictional and passive resistance of the <br /> soil may be combined without reduction in determining the total lateral resistance. A one-third increase <br /> in the above value may be used for short duration, wind or seismic loads. <br /> Site Coefficient <br /> The soil profile as identified in UBC Section 1636 that most closely resembles the site conditions is So. <br /> Accordingly, the following seismic coefficients and near source factors are presented for your <br /> consideration. <br /> So B 0.36 0.54 1.0 1 1.0 <br /> Floor Slabs and Exterior Flatwork <br /> Concrete slab-on-grade floors should be underlain by a capillary moisture barrier consisting of a 4-inch <br /> thick blanket of free draining granular material. Gradation of this material should conform to the <br /> following, as determined by ASTM Specification D422: <br /> Sieve Size Percent Passing <br /> '/o-inch 100 <br /> No. 4 0 <br /> In addition, a moisture vapor barrier consisting of a minimum 10 mil polyethylene sheeting should be <br /> placed above the granular blanket in interior floor slab areas where floor coverings are anticipated. A <br /> two-inch thick layer of damp clean sand (Unified Soil Classification: SW or SP) should be placed above <br /> the membrane. The membrane serves to reduce the migration of moisture vapor through the slab, <br /> while the sand promotes uniform curing of slab concrete and provides protection of the membrane to <br /> punctures during the construction process. Care should be taken to properly lap and seal the <br /> membrane, particularly around utilities, to provide a vapor tight barrier. <br /> 1417 No.Market Blvd.,Suite 1 . Sacramento,CA 95834 • (916)568-5856 • Fax: (916)568-5813 <br />