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Port of Everett—South Terminal Wharf& Electrical Upgrades—Phase 2 121 <br /> The equation for q-z springs is: <br /> S e <br /> F = qt *rtrg <br /> * —,c *At <br /> utrg <br /> Where: <br /> F= Nominal tip Resistance in kips, <br /> qt = Nominal unit tip resistance in ksf, <br /> rtrg =target resistance= 100%(decimal), <br /> 6= incremental movement variable, <br /> Strg = movement at rtrg, <br /> 0= an exponent,0<<0<_ 1,and <br /> At=Area of pile tip in square feet. <br /> We determined the nominal unit shaft and tip resistance from the static analysis results mentioned <br /> previously and the resistance charts are provided in Figures 25 through 27.Additional parameters for use <br /> in the above equations are provided in Table 19. It should be noted that toe springs provide resistance only <br /> in compression, and the spring equations do not include elastic compression of the pile. <br /> Table 19 — Parameters for Use in Spring Equations <br /> Spring Case St,, 9 <br /> t-z(shaft) 0.2 0.3 <br /> q-z(tip) 1.0 0.6 <br /> Field Verification of Axial Resistance <br /> We recommend that the axial resistance of each pile be field-verified based on a dynamic pile driving <br /> formula used in conjunction with the results of monitoring while driving the final few feet of pile.The <br /> results of the dynamic pile driving formula should be calibrated to load test or CAPWAP results on a limited <br /> number of piles. <br /> The So equation (Danish Formula) presented below provides a method of estimating capacity from the <br /> hammer energy and blow count. It is a simplification of the rational pile formula and is based on the <br /> impulse-momentum principles of the hammer/pile system. <br /> The So equation is: <br /> ( aEr <br /> Q= S+So, <br /> NV <br /> V 19232-01 <br /> HARTCROWSER December 6,2017 <br />