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ADaPT EnAineerieY, lnc. <br />Tablc 1 <br />Allowable End Bcaring Capacity <br />Depth (fcet) Allowable Bearing Capacity (ts� Limitlng Pofet Resistance (taQ <br />15-28.5 6.0 D/I3 30 TSF <br />Notcs: D= the embzdmcnt depth (in feet) into the bearing laycr. <br />B = pier diameter (feet). <br />Priciional Capacities: For Gictional resistance of the drillcd piers, acting both downward and in uplift, we <br />recommend using the allowabte skin friation value listed in Table 2. Wc recommend that frictional <br />resistance be neglected in the uppermost 2 feet bclow the ground surface. The allo:vable skin friction <br />value presented includes a safety factor of' 1.5. The friction valucs for the glacially consolidated soils <br />may bc applicd for the soils bclow the maximum depth of the test boring. <br />Tabte 2 <br />Allowablc Skin Friction Capacitics <br />Depth (fect) Allowable Skin Friction (tsQ <br />0-2 0.0 <br />2-12 0.15 <br />12-28.5 0.70 <br />Latcral Capacities: �or design against lateral forces acling a�ains: the drilled pier, two methods are <br />typically used. Thc parametcr used to select ihe appropriate dcsign melhod is the lenglh lo picr stif ��-ss <br />ratio L/I', whcre L is the pier length in inchcs, and T is the relative stiffness factor. Thc rclative stiffncss <br />factor (T) shauld bc computed by: <br />T_/GI\o.z <br />llth � <br />where G = modulus oCelasticity (psi) <br />I = moment of incrtia (in°) <br />nh = constant of horizontal subgrade rcaction (pci) <br />The factors B and 1 arc governed by �he intcrnal matcrial strength characterislics of the picc A <br />representative value of nh for thc soil typcs encountered at this sitc is presented bclow in Tablc 4. Picrs <br />with a L/T ratio of less than 2 may be assumed to be relativcly r'gid and acting as a pole. The passive <br />pressure approach m�y be used Cor this condition. Por piers with a L!I' ratio greater than 2, the modulus <br />of suUgrade rcaction mcthod is typically used. IIoth of thesc methods arc discussed below: <br />VoiccStrcam \4'ircicss May 13,:00(1 <br />ADaPT Projccl No. N'A00-40)4 PaEc n <br />