Design and Load Testing of Large Diameter Open-Ended Driven Piles (2015) / Chapter Skim
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From page 23... ...
24 chapter three AGENCY STATE OF PRACTICE FOR LARGE DIAMETER OPEN-ENDED PILES This chapter provides detailed findings on how transportation agencies view and use LDOEPS based on the survey results and follow-up interviews. Some information from the literature review is also included.
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25 prediction methods to larger pile sizes. Specific design issues and questions include: – Prediction and extent of plugging, – Determination of pile capacity/resistance, – Length of concrete infill, – Structural design of concrete–steel section, and – Resistance factor selection.
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26 Common themes in the interviews were the ability to resist large lateral loads and the potential to avoid cofferdams and excavations for pile footings. By taking advantage of the efficient bending resistance of LDOEPs, a few larger piles can be used in a pile bent, eliminating the need for a pile footing and the associated cofferdam when using a large number of smaller piles.
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27 types of concrete LDOEP: a 54-in.-diameter spun-cast posttensioned pile and a 60-in.-diameter full-length pre-tensioned bed-cast pile. NYSDOT also has a standard specification for concrete cylinder piles that can be modified, if necessary, for each project.
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From page 27... ...
28 has been to drive pile to bear on rock, so that calculations of side resistance are not a significant issue for static resistance. NYSDOT noted that they temper the FHWA methods with their dynamic test experiences at other sites.
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29 KYTC noted that the soil properties and limiting values of pile resistance recommended or determined by the API method were adjusted based on KYTC and Terracon experience and the CPT data collected for the project. The CPT data were especially helpful in evaluating limits on mobilized pile resistance.
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30 Setup and Relaxation Twelve of the 16 agencies (75%) evaluate setup and relaxation for each project, although most assume that relaxation will not occur.
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31 FDOT relies heavily on dynamic testing to verify resistance, set tip elevations, and establish final order lengths. The agency has had no significant issues with dynamic testing; however, load test programs did indicate that pile resistance determined by CAPWAP® was conservative compared with static/ Statnamic® testing (Muchard 2005; Kemp and Muchard 2007)
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From page 31... ...
32 – Pile driving formulas for large diameter piles are not sufficient. – Static pile load testing in conjunction with PDA® is needed according to the Caltrans LRFD Amendment to the AASHTO design code (California Department of Transportation 2012)
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