S - Kam Ng PhD Dissertation Final.pdf - Digital Repository of CCEE ...

66WEAP analysis based on the Iowa Blue Book method uses the Iowa DOT pile designcharts found in the Iowa DOT LRFD Design Manual Section 6 under the website(URL://www.iowadot.gov/bridge/manuallrfd.htm) for determining the unit shaft (q s ) and unittoe (q t ) resistances. The Iowa Blue Book method initially applied the wave equationconcepts to develop the end bearing chart and applied the Meyerhoff’s semi empiricalmethod and Tomlinson method to develop the shaft resistance chart. The charts obtainedfrom the combination of these methods were adjusted to correlate with the static load testresults performed during the past 30 years in Iowa. The unit shaft resistance is determinedby dividing the friction value in kips per foot chosen from the design chart withcorresponding to the width of the steel H-pile, the soil description and the SPT N-value withthe perimeter of the boxed section of a steel H-pile. However, a coating perimeter for Hsection was assumed for calculating the unit shaft for sand or cohesionless soil. The total toeresistance in kips is determined by multiplying the unit end bearing value in ksi with thecross sectional area of the H-pile for any soil conditions, assuming soil plug does not occur incohesive or clay soil.Iowa DOT method uses the SPT N-values as the only soil parameter which is inputinto the WEAP’s variable resistance distribution table with respect to the depth where theSPT N-values are taken. Static geotechnical analysis and driveability analysis cannot beperformed because the SPT N-values are only served to define the relative and approximatestiffness of the soil profile. Nevertheless, the bearing graph analysis can be performed toestimate pile resistance.2.5.9. Output optionsThe three WEAP analysis output options are (1) bearing graph calculation; (2)driveability analysis; and (3) Inspector’s Chart. The first option is the most commonly usedWEAP analysis. In the bearing graph calculation, ultimate pile resistance, hammer stroke,pile stresses are plotted as a function of hammer blow count. Figure 2.14 shows the sampleoutput of the bearing graph analysis, which also lists the hammer type, dynamic soil