Design and Load Testing of Large Diameter Open-Ended Driven Piles (2015)

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102 APPENDIX C Interview Notes of Selected States Using LDOEPs

103 NCHRP 45-05 Interview Notes – Alaska Department of Transportation Page 1 of 3 Agency: Alaska Department of Transportaon and Public Facilies Participants: Dave Hemstreet, P.E. Interview Date: April 22, 2014 Primary interview was with Mr. Helmstreet. A follow-up phone call was made to Mr. Elmer Marx, P.E. in Bridge Design to supplement two points. Mr. Marx’s comments are in italics below. Design Piles are steel pipe, 48in diameter is largest used to date. Typically granular, cohesionless soils. Use FHWA Beta method with modified beta factors. o Modificaons are based on recent research report “CAPWAP-Based Correlaons for Esmating the Static Axial Capacity of Open-Ended Steel Pipe Piles in Alaska, December 26, 2012.” o Study based on 20 years of driving records and PDA data. o Use an equivalent plug to esmate base resistance. o Have applied the results of the research to a couple of recent projects and found that the dynamic tests matched well with the modified static analysis calculations. Previous design method was to use unmodified FHWA methods in the computer programs DRIVEN and Allpile. Shortcomings of this approach believed by ADOTPF: o The plug was not being modeled correctly. o The calculations did not properly “scale up” to larger sized piles. o Idaho DOT did a study and determined that if the SPT N value was scaled down, the Nordlund method gave reasonable results. Piles are concrete filled (with rebar) at least down to point of fixity required for seismic response. Notes from Mr. Elmer Marx, P.E., Bridge Design Use of LDOEPs began in the 1970s during and after Alaskan Pipeline project. Steel pipe piles 48in in diameter were used on that project. ADOTPF saw many of the benefits and adopted them for transportaon, using the piles for pile bents to replace large pile footings. o Less environmental impact – pile bents remove need for excavaon and cofferdams for large pile footings containing numerous H-piles or small pipe piles. o Quick installaon. ADOTPF is utilizing accelerated bridge construcon due to the very short construcon season in Alaska. Also restrictions for fish, wildlife, etc. Fewer large piles can be installed quickly and superstructure work started sooner.

104 NCHRP 45-05 Interview Notes – Alaska Department of Transportation Page 2 of 3 o To help reduce environmental issues with impact hammers, piles are vibrated in to extent possible, and then completed with impact hammer. o Benefit of adopng 48in pipe piles has been seen with changes in seismic design codes. No major changes needed to meet updated codes since the pipe piles were suitable for the updated loadings. Due to supply issues and seismic design issues, ADOT has stopped using ASTM A252 steel pipe and adopted three types of pipe: o ASTM A53 for small diameter piles o API5L PSL2 (pipeline pipe) – very detailed specifications for chemistry and tolerances on manufacture; designed for seismic applications. o Spiral weld pipe – worked with Skyline Steel to develop and transioning to this for more projects. Plug Formation Evaluate plug formation for each site, looking also at previous work nearby No set procedure or depth of plugging Drivability Analysis Typically do not do full drivability analysis for most loading condions. Will check driving stresses with low penetration as well as with penetration at esmated p, but don’t typically do a full driveability analysis showing expected blowcount and stresses for the entire depth. If a project has very high loads, or high driving stresses are ancipated, will do wave equaon analyses to verify the designed piles can be installed with typical hammers used. Contractors are required to submit wave equaon analysis with equipment submittal. Dynamic Testing Frequently used, especially for fricon piles Take advantage of increased resistance factors for higher load demands. No static load tests No pre-producon testing. Dynamic test at least one pile per bent/substructure. Bridges over 100 feet wide may get two tests. If capacies are not coming up, will do either a restrike or test more piles within that bent (in order to use a higher resistance factor), or combination of the two. Pile Damage Not frequent, but somemes have toe damage for piles driving into rock, particularly sloping bedrock.

105 NCHRP 45-05 Interview Notes – Alaska Department of Transportation Page 3 of 3 Lessons Learned Do not use static analysis methods alone to predict resistance. They are too conserva ve due to not scaling up to larger diameters. Have observed piles reaching a maximum resistance and then not gain addi onal resistance with increased depth. One idea is that the soil is liquefying close to the pile as it is being driven, causing reduc on or loss of side resistance. Some gain occurs after driving has completed, but not to level expected. Interested in comparing other agencies experiences with dynamic testing in granular materials to see how they compare with ADOTPF.

106 NCHRP 45-05 Interview Notes – California Department of Transportation Page 1 of 1 Agency: California Department of Transportaon Participants: Sharid K. Amiri, Ph.D., P.E. Interview Date: May 6, 2014 Dr. Amiri shared experiences in design oversight capacity, specific to the projects in his region of Caltrans and are not for the enƒre Caltrans. A geotechnical manual for the department is currently being developed, with some modules available on-line. The deep foundations module is still in development. Design LRFD was used per AASHTO (4th edition) guidelines and Caltrans Amendment dated 2008 in geotechnical design of the deep foundaon for these projects. Two types of LDOEPs o “Pipe Piles” – does not include concrete infill (with or without reinforcement) o “Cast in Steel Shell Piles” (CISS) – includes concrete and reinforcement steel. CISS piles were 48 inch in diameter with Shell thickness of ¾ inch. These piles are typically designed to withstand significant seismic and lateral loading. They also contributed to a reducon in the footprint during construcon. Issues How to demonstrate/verify nominal axial resistance o PDA alone for large diameter piles does not appear to adequately measure axial loading. o Pile driving formulas or large diameter piles are not sufficient o Pile load testing (PLT) in conjuncon with PDA is needed. ( Ref: Caltrans LRFD Amendment) o Load tests need to be taken to failure to be˜er calibrate resistance factors, but this is difficult Vibrations from installaon o Installaons in highly urbanized areas impacting nearby residences o Need more monitoring data for LDOEP installaons since most information is for small diameter piles. o Pile vibration monitoring was performed for these projects including specific data for these large diameter CISS piles. This information is being gathered at the present me.

107 NCHRP 45-05 Interview Notes – Florida Department of Transportation Page 1 of 2 Agency: Florida Department of Transportaon Participants: Larry Jones, P.E. Rodrigo Herrera, P.E. Interview Date: May 2, 2014 General FDOT has had three recent bridges built using concrete LDOEPs: o Hathaway Bridge Replacement (Bay County) o St. George Island Bridge Replacement (Franklin County) o Trout River Bridge (Duvall County) Many details of the contractors’ experience summarized in the following papers: o Muchard, M. (2006). “Statnamic Load Testing of High Capacity Marine Foundaons”, 54th Annual Geotechnical Engineering Conference, University of Minnesota. o Kemp, J.J. and Muchard, M. (2007). “Recent Experiences with Concrete Cylinder Piles in Florida”, GSP 158 Contemporary Issues in Deep Foundaons, Geo-Denver 2007, Geo-institute of ASCE. Design and Construcon Two standard concrete pile types: o 54 inch diameter spun-cast post-tensioned. Piles are cast in 16-foot segments. o 60 inch diameter full-length pre-tensioned. Steel pipe piles (42in diameter) only used once on minor bridge on state land. Pile p elevations and pile resistance are esmated during design using FBDEEP so›ware. Dynamic testing used to verify resistance, set p elevations, and establish final order lengths. No significant issues with dynamic testing. Load test programs did indicate that pile resistance determined by CAPWAP was conservave compared to static/Statnamic testing. FDOT has standard pile design detail drawings for both pile types. Have also had static and Statnamic load testing as detailed in the papers by Muchard. Do not assume plug formation during driving and did not observe it on the first two projects, in fact the opposite was observed, with a column of soil and water raising inside the void. Je£ng is allowed if sufficient measures are in place to prevent turbidity and the project locaon is not in a sensitive waterway. Lessons Learned Proper quantity, size and locaon of vent holes in the sides of the piles is very important.

108 NCHRP 45-05 Interview Notes – Florida Department of Transportation Page 2 of 2 o Insufficient venting led to longitudinal cracking in several piles. o As the pile is driven, the pile experiences axial shortening during a hammer blow. The column of water within the void section is incompressible, applying excessive uniform stress against the pile cylinder, resulting in longitudinal cracking. o Contractor used an airlift to remove water/soil from inside the upper portion of the pile void to reduce the potential for excessive stress, and driving connued thereaer. o Addional vents and larger vents added to the piles reduced/eliminated the cracking issues related to poor venting. When driving concrete cylinder piles, the pile cushion needs to have a void with the same size as the void of the pile. Using a solid pile cushion may result in it being pushed into the void, generang radial stresses that initiate longitudinal cracking or spalling at the pile head. This has also been found to be true by FDOT for square piles with voids extending through the top of the pile. Have also had experience where contractor welded a steel ring inside the helmet to help hold and align the pile cushion. This ring apparently ended up contributing cracking due to misalignment and/or radial stresses at the top of the pile. Research University of South Florida (USF) “Corrosion Performance of Concrete Cylinder Pile” Final report submi‹ed to FDOT on 2005. USF inspected the piles at various bridge sites that experienced vertical cracking and found the piles to be performing very well with regards to resisting corrosion. University of Florida “Determinaon of Axial Pile Capacity of Pre-Stressed Concrete Cylinder Piles” Final report submi‹ed to FDOT on 2004. The research was used as the basis for updates to FBDEEP soware. University of Florida “Development of Modified P-y Curves for Large Diameter Piles/Drilled Shafts in Limestone for FBPIER” Final report submi‹ed to FDOT on 2004. The research was used to develop a lateral resistance model for Limestone, and implementaon in design soware (currently known as) FB-Mulpier.

109 NCHRP 45-05 Interview Notes – Kentucky Transportation Cabinet Page 1 of 3 Agency: Kentucky Transportaon Cabinet (KYTC) Participants: Darrin Becke, P.E. – KYTC Transportaon Engineer Specialist Ron Ebelhar, P.E. – Terracon, Inc. (Consultant to KYTC) Jeff Dunlap, P.E. – Terracon, Inc. (Consultant to KYTC) Interview Date: April 21, 2014 KYTC has had very liƒle recent experience with LDOEPs. The experience that is the subject of the interview is from a test pile program conducted for the project US 68 / KY 80 over Kentucky Lake, report dated January 23, 2014. Items in italics are excerpted from the report. Design issues that led to considering LDOEPs and having a test pile program Seismic loading due to proximity of New Madrid fault Barge impact loads Difficult soil/geologic condions for drilled shafts o Residuum of Fort Payne Formation – chert residuum that behaves as a dense gravel, some silt and clay layers. o Concern about potential difficulties with keeping drilled holes open, and that full depth temporary casing would be required. o Not confident that a clean shaft boom could be achieved. o Chert formation hard on drilling tools, driving up costs for contractors Transion to LRFD provided opportunity to evaluate resistance factors with load tests Experience of geotechnical consultant (Terracon) with LDOEPs for marine structures Concern of small diameter open-end piles plugging and not reaching the bearing strata Concern with closed-end piles not reaching the bearing strata Efficiency of fewer, larger piles providing stiffness for seismic and impact loads Design Process and Methods Mr. Ebelhar’s experience with offshore structures supported on LDOEPs includes use of API RP 2A method for design. His experience, and that of industry, indicates very good agreement with load test data. He has designed several projects around the world in similar soil/rock condions. Significant differences between API and FHWA methods that are beneficial when using API: o API evaluates fricon inside of pile plug formation, rather than a more arbitrary selection by FHWA o API limits side resistance to a maximum mobilized value whereas FHWA (Nordlund) does not include an upper limit. The soil properes and limiting values of pile resistance recommended/determined by API method were adjusted based on KYTC and Terracon experience and the CPT data collected for the project. CPT data were especially helpful in evaluang limits on mobilized pile resistance.

110 NCHRP 45-05 Interview Notes – Kentucky Transportation Cabinet Page 2 of 3 Key question was development of the plug – if the plug is being relied upon to either achieve penetration into the chert or to achieve the nominal pile resistance, how could the certainty of the plug developing and its locaon be determined? o Wanted to keep the pile open to get it down relavely easily, but needed it to plug to get the pile to drive the minimum distance into the chert required for fixity. o Experimented with where to create the plug, designing insert plates to form the plug at a fixed locaon. Design evaluaons included discussions with Dr. Sam Paikowsky, P.E. and his work on the Sakonnet River bridge in Rhode Island. o A significant concern was related to piling quantity – be able to reliable esmate where the plug would form to get the needed penetration of pile and nominal resistance. o Also concerned with schedule impacts if piles did not achieve required resistance and need to be driven deeper. Drivability and Plug Development Started with the API method internal and external skin fricon, compared to plug forming to determine best point to set the plate to engage the plug. For the test piles, the plate was set higher to have the piles penetrate further into the chert than determined for the design. Wanted to be sure that the piles were bearing in the chert. The test pile results indicated a silty sand with gravel layer that helped to increase the pile resistance if the plug could be engaged at this stratum. Fine sands and silt/lean clay zones were not adequate to develop end bearing on the plate. Axial pile load testing indicated that the 48-inch-diameter piles were more likely to achieve a plugged condition with the steel constrictor plates located 98 feet above the design pile „p than the 72-inch-diameter piles at the test loca„ons. When the piles were driven to or near the design pile „p elevation at the test loca„ons, the 72-inch-diameter piles did not achieve a fully plugged condi„on with the steel constrictor plates located 98 feet above the pile „p. Dynamic Testing and Wave Equaon Analysis Selected dynamic pile testing records were reviewed by a sub-consultant to Terracon with extensive pile testing experience to consider other methods of improving the match quality and the es„ma„on of static pile resistance. These analyses used a single-toe pile model, and while the initial analyses performed by the contractor’s testing consultant used a double-toe model. o Radial or radiation damping models were applied to the signal matching analysis. The radiation model assumes some energy is radiated away from the pile „p instead of being completely confined to static and dynamic responses of the soil shear along the pile and at the pile toe. o For the dynamic records where radiation damping was applied, the model generally resulted in a significantly be‘er signal match quality, indica„ng the

111 NCHRP 45-05 Interview Notes – Kentucky Transportation Cabinet Page 3 of 3 radiation damping allows CAPWAP to be­er model the signals recorded by the dynamic pile testing equipment. o The pile resistances calculated with CAPWAP using the radiation damping model also generally produced higher end bearing resistance values than the CAPWAP models without the radiation damping. It appears that the radiation damping model is be­er suited for es„ma„ng the end bearing component of the piles when less pile set is experienced per hammer blow. This is the case when the constrictor plates are engaged on the dense granular soils. Wave equaon analyses indicated that plugged piles would have high stresses. Addionally there was concern that localized high stresses might be encountered due to the presense of the chert. Testing on the piles typically did not approach as high values as expected. Experimented with wall thickness (tw ) during wave equaon analysis and the testing program 48” dia. pile – tw = 1.5” and 1”(48” piles were not selected for final design of the bridge) 72” dia. pile – tw = 2” and 1.5” (selected 2” for final design of the bridge) Lessons Learned It is important to be certain that the plug forms where it is counted on. Using plates can reduce risk of plug not forming as intended.

112 NCHRP 45-05 Interview Notes – Louisiana Department of Transportaon and Development Page 1 of 2 Agency: Louisiana Department of Transportaon and Development Participants: Ching Tsai, P.E. Chris Nickel, P.E. Interview Date: April 21, 2014 General Typically use concrete cylinder piles rather than steel pipe. Concrete are less costly. Piles used mostly in coastal areas. 54in diameter spun cast is very common. Had some issues with pile cracking, especially near the top of the pile. Adjustments to the detail for strands and number of turns reduced cracking. Design Use FHWA methods for design, but no set “standard” for assumpons with regard to plug formation. For LA 1 project, started by assuming pile will plug 50% for static analysis, but always look at each case separately. One project with 54in diameter, 160ft long piles had test piles instrumented with strain gauges near the boŒom. Using Davisson’s method, the end bearing is 55% of fully plugged capacity. If plunging is the criterion, then 83% plug efficiency. Try to balance size of pile, capacity, and quantity of piles. Available driving equipment and barge access (dra˜) tent to limit the pile size that can be used on a particular project. Setup is accounted for in design. Typically do a restrike program up to 14 days after initial drive. A paper was published in the proceedings of the 2014 GeoCongress (Geo- Institute of ASCE) including LA 1 test program and investigation of size effect on setup. Load Tests Very few static tests, relying on statnamic and dynamic testing Pre-producon test piles will be specific to a project and not always included. Test piles driven during producon, including restrikes to develop setup curves and establish driving criteria. Number of piles tested depends on site variability, not a minimum number per bent, etc. For LA 1, barge access dictated test pile locaons. Drivability Assessment Not usually evaluated during design. Wave equaon analyses performed based on contractor equipment submittals. Test piles are monitored and adjustments made to WEAP models based on field results.

113 NCHRP 45-05 Interview Notes – Louisiana Department of Transportaon and Development Page 2 of 2 Driving Aides Evaluated on a case by case basis Je ng is somemes allowed, usually no more than through the scour zone where no side resistance is counted on for design. Lessons Learned Comfortable with spun cast concrete piles, paying aention to details such as reinforcement at the top (for driving stresses) and vent hole placement to relive pressure inside the pile during driving. At LA 1 project, comparing the cylinder piles to other test piles at the same locaon, the unit skin fricon appears to be slightly smaller for the cylinder piles. When combining the effects of larger than calculated p resistance, the results are good total resistance predicon, but not as good for individual components.

114 NCHRP 45-05 Interview Notes – Minnesota Department of Transportation Page 1 of 2 Agency: Minnesota Department of Transportaon Participants: Gary Person, P.E. Derrick Dasenbrock, P.E. Interview Date: April 24, 2014 MnDOT began using LDOEPS about 10 years ago. Their experience to date is with 42in diameter steel pipe piles. Design Steel pipe piles, 42in diameter on all projects to date; though have one project tout for bid with 30in diameter piles and an upcoming river crossing that may have piles larger than 42in diameter Use FHWA design methods (Meyerhoff, Nordlund) and CPT based methods when designing for non-rock bearing with no modificaons. Some checks were conducted with A-Pile (but not principal design). Hastings Crossing was Design-Build procurement with analysis by consultant. Most projects have been to rock, as rock has been ‘reasonably close’ and therefore cost effective. Believe that the static resistance methods are reasonable esmates of the long term resistance of the pile, but not always easily demonstrated with dynamic testing methods. Also: lack of reliability and repeatability. Due to infrequency of use, there is also concern with the PDA expertise and appropriate modelling of the pile and proper selection of associated damping/quake needed for analysis. Most piles have been driven to refusal on rock, so side calculating static side resistance not as important as the limiting structural resistance of the pile. Plug Formation So far have not experienced significant plug formation. Large piles have thus far exclusively been used at ‘sandy’ fluvial sites (river crossings). Currently believe that could be that the large velocies generated by driving result in the pile “cookie cuœng” through the soils at the project sites. Also have granular materials so could be some local liquefaction of the sands at the pile- soil interface allowing free movement of the pile relave to the soil inside. Drivability Analysis Perform initial check during design for larger diameters and special condions (such as needing to penetrate a hard layer to get to minimum p) where high driving stresses are ancipated to verify the designed piles can be installed with typical hammers used. Contractors are required to submit wave equaon analysis with equipment submittal.

115 NCHRP 45-05 Interview Notes – Minnesota Department of Transportation Page 2 of 2 Dynamic and Load Testing Wakota Bridge provides a good case history of early use and testing of LDOEPs by MnDOT. Main issue is demonstrating required resistance via dynamic testing methods. In MnDOT experience, initial drive PDA/CAPWAP appears to consistently under-predict capacity when compared with restrikes, static methods, and rapid load test methods. Having recognized this, rapid load testing has been required on all projects following to Wakota. Difficulty with dynamic testing is being able to provide larger enough hammer to move the pile to demonstrate the required resistance once pile firmly bearing on rock or any setup has occurred. Have adopted the approach to perform rapid load tests (Statnamic) to be‹er assess the static pile resistance and help correlate/calibrate PDA data to provide comfort level with results. Partly a design/construction process issue where bridge designer has criteria of demonstrating required resistance at end of drive. ConŒnued use of rapid load tests with PDA testing should increase confidence that end of drive resistance can be correlated with long term static resistance. Lessons Learned We have found the under-predicŒon of the dynamic formula at Œme-of-drive to be problematic as it ‘spooks’ the field engineers who are very worried that the measured capacity is someŒmes even below the factored capacity (and therefore well under the required nominal capacity). Restrikes should be included to assist in demonstrating that there are ‘driving effects.’ Statnamic or static load tests should be used to verify, particularly as an agency is beginning use of LDOEPs. ExisŒng FHWA design methods appear to provide reasonable esŒmates of static (long- term) pile resistance. Use of LDOEPs has been very successful and now the first driven piling opŒon considered for large river crossings.

116 NCHRP 45-05 Interview Notes – New York State DOT Page 1 of 3 Agency: New York State DOT Participants: Steve Borg, P.E. – Civil Engineer II (Geotechnical Engineer) Interview Date: April 17, 2014 Note: Items in italics are from previous interview for Synthesis Project 41-10 (Developing Produc†on Pile Driving Criteria from Test Pile Data) dated August 31, 2010 General Experience Typically use concrete cylinder piles with 36in to 54in diameter. Steel pipe is usually less than 36in, though have had a few projects with 36in pipe piles. Pile lengths of up to 160ft are common on Long Island. Soil condiŽons Upstate are typically sands, silts, gravels and clays, and other glacial deposits. Long Island is typically sands and some clay. Gave a summary of a few example projects. o Near Saratoga – 36in cylinder piles, could not get shaft resistance in the gravels, but achieved adequate setup in the clays. For piles in gravel that were not ge•ng capacity, ended up driving H-Piles through the void of the cylinder to rock. o Chautauqua Lake – 36in cylinder piles in lacustrine deposits and till o Pedestrian Bridge north of NYC – all precast bridge with single column piers. Drove 36in cylinder piles with no je•ng. o Jamaica Bay and others on Long Island – 54in cylinder piles using pre-je•ng LDOEPs usually selected to avoid cofferdams for pile footings while providing good bending resistance. Cylinder piles used for pile bents, all plumb piles. On Long Island, cylinder piles selected for corrosion resistance, Ždal scour considerations. Seismic forces someŽmes also play into the considerations. No problems with cylinder pile manufacturing. All piles come from Bayshore. Design Design approach is to use AASHTO/FHWA (methods listed in survey) tempered by experience and dynamic tests of previous projects. Lateral design by LPILE and GROUP . No uplift. For plug formation – use recommended GRL WEAP method for increasing mass of soil at Žp of pile, not increasing stiffness of pile. Will usually do a sensitivity analysis by varying plug length. For setup – NYSDOT has history of dynamic tests with restrikes documenting setup in areas where LDOEPs are typically used. Generally see 40% to 50% setup, even in the Long Island sands. Restrikes typically done 24 hours after driving. o The biggest challenge for NYSDOT is developing good es†mates of set up in the clays soils found in certain parts of the state. Experience indicates that setup †mes can range from 24 hours to one month. The project schedule is typically set such that there is not †me to allow a test program to fully investigate pile set up .

117 NCHRP 45-05 Interview Notes – New York State DOT Page 2 of 3 Piles tend to be over driven (driven to higher resistance than necessary if setup in clay was beƒer defined) in order to meet the schedule. No relaxaon. (We somemes see relaxaon when H-piles are driven to shale bedrock) Load tests Used static + dynamic 25 to 30 years ago. Now only dynamic tests, both for measuring resistance/setup and for damage control (cracking and damage to concrete). Have not uses Statnamic. Dynamic tests are somemes done on pre-producon test piles to set order lengths, others on producon piles only. Some projects give contractor the opon to have sacrificial test pile or use producon pile. Have not performed lateral load tests. Dynamic tests always include signal match analysis using CAPWAP so‰ware. NYSDOT will use the base resistance from the end of initial drive with the side resistance from restrike blows to esˆmate the static pile resistance. For very long piles, the side resistance from several blows is superimposed to esˆmate the side shear resistance for the pile. Drivability Analysis Drivability analysis performed during design using an assumed driving system. Most contractors tend to use one of two hammers: Conmaco 5300 or Raymond 60X. (Diesel and hydraulic hammers have also been used on cylinder pile projects.) Wave equaon analysis also performed using contractor submi“al once received during construcon. Construcon and Quality Control Driving Criteria o Wave equation analysis is typically used to evaluate the contractor’s hammer system submiƒal and set the driving criteria. The inspectors are provided an acceptance blow count and minimum hammer energy or stroke criteria. Restrike blows are only used if piles do not achieve the desired resistance at the esˆmated drive length o For soils condiˆons or large projects where High Strain Dynamic Test (HSDT) are more suitable, the HSDT are used to set the driving criteria. One test pile (a producˆon pile) per substructure is tested at initial drive and with a 24-hour restrike. The inspector is provided the acceptance blow count and hammer performance criteria based on the HSDT results. o With pre-cast pre-stressed cylinder piles, pre –producˆon HSDT is performed to set pile lengths and determine the driving criteria. Evaluation of tensile and

118 NCHRP 45-05 Interview Notes – New York State DOT Page 3 of 3 compressive stresses in the piles during driving is also a major part of dynamic testing of these piles. Pre-Jeng o On Long Island, pre-jeing is typically used. No pre-jeng when LDOEPs used Upstate. o With pre-jeing on Long Island, temporary casing is also required to prevent debris falling into the pre-jet hole. The area has a lot of riprap and such for scour protec‚on. it often ends up in or near channels, etc. Had a project that debris kept falling in to the pre-jet holes, obstructing piles. Typical process is to vibrate casing, jet, drive pile, pull casing. Dynamic tests are done on produc‚on piles to monitor driving stresses, prevent damage, and check resistance. Can be one per bent or one every other bent (especially when construc‚ng bridge in two phases). On one project had a sacrificial pile that was intentionally overstressed to measure maximum compressive stress in the pile. The results showed that 4.5ksi was a good limit of concrete strength – started to fail/crumble beyond that. No pile points or other toe protec‚on used. NYSDOT has a special specification for concrete cylinder piles. It can be modified for a specific project or used as wrien. No experience with splicing cylinder piles – either pre-planned mechanical splices or unplanned field splices. Lessons Learned Pre-jeng with debris – learned to use temporary casing, include a contingency amount in the contract for debris removal. Measurement of 4.5ksi stress for concrete piles mentioned above. It was 36in diameter pile. It is crucial to take measurements early in the driving after jeng to measure and monitor tensile stresses. Experience that fine cracking will occur in the cylinder piles, but usually terminate at the horizontal joints between the pile segments. Need to have pile lengths ordered to have sacrificial length at top of pile to be cut off to provide sound pile at top for connection to bent cap. This avoids need for buildups. Have tried using wood plugs to plug the pile, but have not had any success with this technique. Obstructions are always an issue in loca‚ons NYSDOT uses these pile.