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24 I Port of Everett—South Terminal Wharf& Electrical Upgrades— Phase 2 <br /> Hammer Type. We performed our analyses for an APE D50-52 open-ended, diesel impact hammer.This <br /> hammer was chosen since the APE D50-52 hammer is the very similar to the APE D50-42 hammer that was <br /> used for recent wharf upgrade pile driving at the north end of the site.This hammer is manufactured with <br /> an 11.03 kip piston (ram)and has a stroke of 11.25 feet at the maximum rated energy of about 124 kip- <br /> feet. We used the recommended parameters in WEAP for hammer efficiency, pressure, and stroke. <br /> We also analyzed an APE D100-52 as a hammer capable of mobilizing the allowable resistance of 660-kips <br /> necessary to achieve specified allowable compressive resistance for pile rows F and G. This hammer is <br /> manufactured with an 27.56 kip piston (ram) and has a stroke of 11.42 feet at the maximum rated energy <br /> of about 310 kip-feet. It is a considerably larger hammer than the APE D50-42. We used the recommended <br /> parameters in WEAP for hammer efficiency, pressure, and stroke. <br /> Pile Type. We used 18- and 24-inch-diameter close-ended steel pipe piles for the analysis,taking into <br /> account pile stick-up above the mudline. Our previous pile-driving experience suggests that it is often <br /> difficult to drive thin-walled pipe piles. Based on this, we used a minimum wall thickness of 1/2 inch. <br /> WEAP Results.The maximum predicted blowcount and compressive stresses during steel pipe pile <br /> driving for each of our analyses are shown in Tables 20 and 21.The compressive stresses remain below <br /> 45 ksi (0.9*Fy),which is the maximum allowable driving stress, assuming grade 50 steel.The results of the <br /> WEAP analyses indicate that the APE D50-42 hammer is likely sufficient to the achieve allowable <br /> resistances show in Table 20 with relatively low driving resistances.To mobilize the allowable resistances <br /> provided in Table 21, particularly for Rows F and G, an APE D100-52 hammer may be more appropriate. <br /> However,with the larger hammer size comes a greater risk of pile damage.The contractor's analyses <br /> should assess their entire proposed pile system to assess drivability independent of our preliminary <br /> analyses. <br /> Table 20 — WEAP Analysis Results for APE D50-52 Hammer <br /> Allow. APE D50-42 Hammer <br /> Pile <br /> Compressive <br /> Pile Rows Diameter Max Compressive Max Blows per <br /> Resistance <br /> (in) (kip) Stress (ksi) Foot <br /> A,B,C 18 250 32.1 21 <br /> A' 24 300 33.4 29 <br /> D,E 18 275 32.6 25 <br /> F,G,G' 24 350 31.0 39 <br /> 19232-01 <br /> December 6,2017 <br /> W%RTCROWSER <br />