2222 LOWER NORTON AVE 2018-01-01 MF Import

6.0 RECONIMENDATIOILTS 6.1 PILE FOUNDATION SUPPORT 6.1.1 A[lowable Axial Pile Capacities We recommend that 18-inch diameter augercast piles be designed based on the allowable axial compressive pile capacities presented in Figure 3. These axial capacities are based on a factor of safety cf about 3, applied to the combined ultimate skin and tip capacities and may Ue increased by about 1/3 for short-term loads, such as wind or seismic. Recommended allowable axial tension capacities of 18-inci� diameter augercast pile are presentcd in Figi!re 4. These capacities are based on a factor of safety of about 2, applied to the ultimate skin capacities, and include the weigtit of the pile. The above allowable axial capacities assun�e that augercast piles will be in installed at spacings no closer than about 3 diameters, center-to-center. 6.1.2 Pile Sett[ements �; i Our analyses indicate that 18-inch diameter augercast piles, designed and constructed in accordance with the recommendations presented in this report, will limit post-construction i foundation settlements to about 1/2-inch. The majority of this settlement is expected to result I: from elastic soil-pile response occuning almost immediately upon application of foundation loads. 6.1.3 Lateral Pile Capacities Lateral pile response curves, showing pile head deflection, bending moment, and shear for ? 8- inch diameter augercast piles are shown on Figure 5. T hese lateral response curves are for static lateral pile head loading, for the case of full fixity in the pile cap. These curves are appropriate for single piles or piles in small groups of about 10 or fewer. As discussed above in subsection 4.4, the surficial hydraulic sand fill layer covering the site may � be subject to a significant loss of strength during a severe earthquake. Our analyses indicates � that for a given deflection, in order to approximately account for loss of sapport during an � earthquake, the lateral capacities of 18-inch diameter augercast piles given in Pigure `i should k� be reduced by about 50 percent. tt I 6.1.4 Pile Installation Capacities Augercast piles should be installed using a continuous flight auge: capatle of developing a torque of at least 20,000 f'oot-pounds. To prevent excessive soil disturbance, reduction of the � 503289-01.01 i, 4 January 19, 1995 D,�n�es � MooaF