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6 I 777X Static Test Building <br /> Table 3 - Passive Resistance to Lateral Loads for Spread Footings <br /> Allowable Passive Allowable Coefficient of <br /> Soil Unit <br /> Equivalent Fluid Density Friction <br /> Very dense,very silty sand(Glacial Till) 375 pcf 0.30 <br /> Imported Granular Structural Fill 300 pcf 0.30 <br /> Pavement Considerations <br /> We understand that 13-inch-thick Portland cement concrete pavement overlying a granular base <br /> course will be used. We recommend the granular base course be installed in accordance with our <br /> Structural Fill recommendations with the exception that it be "free draining," defined by having less <br /> than 3 percent by weight passing the No. 200 US Sieve. Similar to our building foundations <br /> recommendations, loose, wet, or organic soils must be overexcavated and replaced to achieve a <br /> suitable subgrade conditions. <br /> Building Slab-On-Grade Considerations <br /> The site soils are suitable for support of a typical building slab-on-grade. We recommend a <br /> minimum 6-inch-thick capillary break material directly below the slab-on-grades. Similar to <br /> pavements,this should be "free draining." Selection and design of an appropriate vapor barrier, if <br /> needed, should be based on discussions among members of the design team. <br /> Modulus of Subgrade Reaction <br /> Modeling building or pavement slab behavior under vertical loads requires a modulus of subgrade <br /> reaction applicable to the soils on which the foundation or pavement section bears. Loading type, <br /> such as static or dynamic loading, has a dramatic effect on the stiffness of the springs. Determining <br /> the subgrade modulus value to be used depends on: <br /> ■ The structural and geotechnical engineer's experience designing similar foundations in similar <br /> soil conditions; <br /> ■ The bearing pressure and area of the foundation; and <br /> ■ Back-checking settlement predicted from structural modeling with geotechnical settlement <br /> estimates forgiven foundation geometries. <br /> For static loading conditions,we recommend the vertical modulus of subgrade reaction (Ks)values <br /> in Table 4. We consider these values a reasonable starting point for an iterative design process. <br /> Hart Crowser should review the displacement estimates from the structural model and perform <br /> settlement evaluations of the specific geometry and loading for compatibility. Based on these <br /> settlement evaluations, modifications to the subgrade modulus used in the structural model may <br /> be required. <br /> r� <br /> 19106-01 <br /> May 29,2015 HARTGROWSME <br />