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7.7 SHALLOW FOUNDATIONS <br />Following the site and foundation preparation recommended above. foundation for load bearing <br />walls and interior columns may be designed as discussed below. <br />7 .7.1 Bearing Capaci(v and Settlement <br />Load bearing walls and interior columns may be supponed on continuous spread footings and <br />isolated spread footings. respectively. and should bear entirely upon properly engineered fill or <br />competent native soils. Continuous and isolated footings should have a minimum width of l4 <br />inches and 24 inches. respectively. All footings should be embedded a minimum depth of 24 <br />inches measured liom the lowest adjacent finish grade. Continuous and isolated footings <br />placed on such materials may be designed using an allowable (net) bearing capacity of 2,000 <br />and 2000 pounds per square foot (psf), respectively. Allowable increases of 250 psf tbr each <br />additional I foot in width and 250 psf for each additional 6 inches in depth may be utilized, if <br />desired. The maximum allowable bearing pressure should be 3,000 psf. The maximum <br />bearing value applies to combined dead and sustained live loads. The allowable bearing <br />pressure may be increased by one-third when considering transient live loads. including seismic <br />and wind forces. <br />Based on the allowable bearing value recommended above, total settlement of the shallow <br />footings are anticipated to be less than one inch. provided foundation preparations conform to <br />the recommendations described in this report. Differential settlement is anticipated to be <br />approximately halfthe total settlement for similarly loaded footings spaced up to approximately <br />30 feet apart. <br />7.7.2 Lateral Load Rcsistance <br />Dennis- l -01 <br />Lateral load resistance for the spread footings will be developed b1- passive soil pressure <br />against sides of footings below grade and by friction acting at the base of the concrete footings <br />bearing on compacted fill. An allowable passive pressure of 250 psfper foot ofdepth may be <br />used for design purposes. An allowable coefficient of friction 0.35 may be used for dead and <br />sustained live load forces to compute the frictional resistance of the footings constructed <br />directly on compacted fill. Safety factors of 2.0 and 1.5 have been incorporated in development <br />of allowable passive and frictional resistance values, respectively. lJnder seismic and wind <br />loading conditions, the passive pressure and frictional resislance may be increased by one-third. <br />I