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� <br />individual spread footings should have minimum widths of twelve <br />(12) and eighteen (18) inches, respectively. <br />Footings bearing on structural fill can be sized for a maximum <br />bearing pressure of three thousand (3000) psf. A maximum <br />allowable load of five thousand (5000) psf is recommended for <br />footi:�gs founded directly on the dense till soils. For the <br />recommended design criteria, it is anticipated that total <br />settlements of footin3s founded on the dense till soils will be <br />about one-half inch, with differential settlements of one-quarter <br />inch. Total settlement estimates of column footings in the <br />Mervyn's store range from less than 0.5 inches at the west side to <br />slightly more than 2.0 inches at the east side for the maximum <br />known depth of existing fill. Radial deflection for differential <br />settlement consideration in this area is about 0.01 inches per <br />foot. Settlement amounts can be reduced, if necessary, by <br />removing greater depths of existing fill or by supporting the <br />structure on deep foundations penetrating to the dense till. <br />Almost all settlements should occur during construction. <br />Continuous footings located in cut-fill transition zones should be <br />considered for additional reinforcement to reduce the risk and <br />magnitude of structural damage resulting from differential settie- <br />ment. The recommended bearing pressure may be increased by <br />one-third when considering short term wind or seismic loads. <br />Lateral loads due to wind or seismic forces may be resisted by <br />friction between the foundations and the supporting structural <br />fill or by passive earth pressure on the foundations. F�r the <br />latter, foundations must be poured "neat" against the existing <br />soil or backfilled around their perimeter with a compacted fill <br />meeting the requirements of structural fill. The passive <br />resistance of undisturbed natural soils and well compacted fill <br />may be taken as equal to the pressure of a fluid having a density <br />of three hundred (300) pounds per cubic foot (pcf). A coefficient <br />of �r.iction of 0.35 may be used between the structural foundation <br />concrete and the supporting subgrade. <br />- 7 - <br />-.� <br />