Tag Archives: Drilled Shafts

TRB paper by andy boeckmann and erik loehr on Thermal requirements for drilled shafts

Andy Boeckmann, Ph.D., P.E. (DBA Senior Engineer) and Erik Loehr, Ph.D., P.E. (DBA Senior Principal Engineer) have published a paper on the topic of thermal testing of drilled shafts in the Transportation Research Board (TRB) journal Transportation Research Record.  Their co-author was  Zakaria El-tayash of Burns & McDonnell. 

As the drilled shaft diameters have increased in size over the years, designers and owners have had questions or concerns about the issues of temperature impacts to concrete durability similar to the issues with mass concrete placement for large structural elements.   Some transportation agencies have recently applied mass concrete provisions to drilled shafts, such as limits on maximum temperatures and maximum temperature differentials.  The temperatures commonly observed in large diameter drilled shafts have been observed to cause delayed ettringite formation (DEF) and thermal cracking in above-ground concrete elements.  This has led to the practice of applying to drilled shafts the control provisions that are based on dated practices for above-ground concrete. However, the reinforcement and confinement (embedded in soil and/or rock below grade) unique to drilled shafts should provide resistance to thermal cracking and possibly other effects of mass concrete temperatures.

Conceptual illustration of crack development in early age concrete with time from internal restraint. Adapted from Bamforth (2018) with permission from CIRIA

 

The paper reviews current requirements of several state DOTs  for addressing DEF and thermal cracking, then establishes a rational procedure for design of drilled shafts for durability requirements in response to hydration temperatures.  DEF is addressed through maximum temperature differential limitations while thermal cracking is addressed through calculations that explicitly consider the thermo-mechanical response of concrete for predicted temperatures.  The recommended procedure includes a detailed five step evaluation process.   Additional alternate steps for mitigation techniques and/or monitoring temperature are detailed as well.   The procedures allow for explicit account of project-specific characteristics, including ground conditions, concrete mix design characteristics, drilled shaft geometry, and the quantity of steel reinforcement.

 

Temperature differential between center and edge of shaft versus time from thermal model and from temperature measurements

 

The methodology was developed from guidance established by ACI and CIRIA and provides a rational means for designing drilled shafts for durability without imposing unnecessary constraints that may exacerbate challenges with effective construction of drilled shafts.  Results from application of the procedure indicate consideration of DEF and thermal cracking potential for drilled shafts is prudent, but provisions that have been applied to date are overly restrictive in many circumstances, particularly the commonly adopted 35 ?F maximum temperature differential provision.

You can get the paper from The Transportation Research Record at the link below.

Boeckmann, A.Z., El-tayash, Z., and Loehr, J.E. (2021). “Establishing and Satsifying Thermal Requirements for Drilled Shaft Concrete Based on Durability Considerations”, Transportation Research Record, March 2021.

NEW PUBLICATIONS ADDED AND UPDATES TO THE WEBSITE

It’s been a while since we have updated everyone on some of the various publications we have added to our website, so I wanted to provide a few links to some of the newer additions to our Publications tab.  One magazine that members of DBA contribute to fairly regularly is Geostrata Magazine.  The Geostrata Magazine is a bi-monthly publication of the Geo-Institute.  You can join the Geo-Institute and gain access to the magazine by following this link:  https://www.geoinstitute.org/publications/geostrata.  Dr. Dan Brown published an article in the May-June 2020 edition about lessons learned from failures during pile installation with regards to driving stresses.  In the January-February 2021 edition, Dr. Erik Loehr contributed an article about recognizing the inherent value in site characterization.  Links for the articles are below.

Brown, D., E. (2020). “Learning from Pile Driving Failures,” Geostrata, May-June 2020.

Loehr, J. E. (2021). “Recognizing Value in Site Characterization – How Cool Would That Be?”, Geostrata, January-February 2021.

Speaking of the Geo Institute, Dan Ding and Erik Loehr recently co-authored a paper in the Journal of Geotechnical and Geoenvironmental Engineering (see link below).

Ding, D., Loehr, J. E. (2019). “Variability and Bias in Undrained Shear Strength from Different Sampling and Testing Methods,”Journal of Geotechnical and Geoenvironmental Engineering Volume 145, Issue 10, October 2019.

An organization that we actively publish papers with is the Deep Foundations Institute (DFI).  We have added papers from the last three years for the DFI Annual Conference as well as the The Journal of the Deep Foundations Institute.  Links to the papers are below.  To join DFI or learn more , click the DFI logo located in the left sidebar.

T.C. Siegel, T. J. Day, B. Turner & P. Faust (2019) “Measured end resistance of CFA and drilled displacement piles in San Francisco Area alluvial clay”,DFI Journal – The Journal of the Deep Foundations Institute, 12:3, pp 186-189.

Graham, D.S. and Axtell, P.J. (2019). “Case History: Comparison of CSL Results to Physical Observations,” Proceedings: Deep Foundations Institute 44th Annual Conference, Chicago, IL, USA, pp 420-427.

Axtell, P.J., Graham, D.S., and Jackson, J. (2018). “Drilled Shaft Difficulties and a Micropile Solution,” Proceedings: Deep Foundations Institute 43rd Annual Conference, Anaheim, CA, USA, pp 93-103.

Graham, D.S., Axtell, P.J., and Iverson, N. W. (2017). “Case History: Large Diameter Micropiles for the Highway 53 Relocation Project,” Proceedings: Deep Foundations Institute 42nd Annual Conference, New Orleans, LA, USA.

Dr. Dan Brown has also recently submitted an article to Pile Driver Magazine, which is a bi-monthly publication of the Pile Driving Contractors Association (PDCA).  To learn more about the PDCA or become a member, click on logo on the left sidebar. The magazine is free to access and can be found by clicking here while the link for Dr. Brown’s article can be found below.

Brown, D. (2020). “A comparison of factors affecting the static axial resistance of drilled and driven piles”, Pile Driver Issue 4 2020, Volume 17 No. 4, pp 60-78.

We have also added a few older papers that David Graham and Paul Axtell have published.  One, a case history for a micropile project, was for the International Society of Micropiles.  The other was for the 34th annual International Bridge Conference.  The links for  the papers are found below.

Axtell, P.J., Graham, D.S., and Bailey, J. D. (2017). “Statnamic Load Testing on a 406mm (16 in) Diameter Micropile,” International Society of Micropiles, Chicago, IL, USA.

Graham, D.S., Hasbrouck, G.T., Axtell, P.J., and Turner, J.P. (2017). “Reducing Longitudinal Demands on Tall Bridge Piers with an Anchored Abutment”, Proceedings of the 34th International Bridge Conference, 2017, National Harbor, MD, USA, pp 668-672.

Finally, we have also updated our About Us tab to reflect the change in leadership announced back in April of 2020 and provide an updated view of our current staff here at DBA.  The names of each individual are links to their respective resume. 

FHWA GEC 10 Update for 2018 Released!

UPDATE!  Posting of the PDF to the FHWA Resource page has been delayed while the formatting issues noted below are worked out. 

CLICK HERE for a Final DRAFT for use until FINAL document is posted by FHWA.

The long anticipated update to FHWA GEC 10 Drilled Shafts: Construction Procedures and Design Methods has finally been released by FHWA, The same team that authored the major update in 2010 that shifted design from ASD to LRFD also completed this update: Dr. Dan Brown, P.E., D.GE, and Dr. John Turner, P.E., D.GE of DBA, Dr. Erik Loehr, P.E. of the University of Missouri and DBA, and Mr. Ray Castelli, P.E. of WSP.

This version is an update of the 2010 publication.  A complete list of changes made since 2010 is in the opening chapter.  Some of the revisions include:

  • streamlining materials covered in other GEC publications (for example, site investigation and lateral loading) to focus on aspects particular or unique to drilled shafts;
  • updates to reflect the evolution of construction procedures, tooling, materials, drilling fluids, and concrete placement;
  • updated design equations for axial loading, particularly for earthquake loading;
  • updated group design to reflect recent changes to AASHTO design guidelines;
  • updates on integrity testing (including use of Thermal Integrity Profiling, or TIP); and,
  • an outline for a process for assessment and acceptance of drilled shafts based on inspection records and integrity tests.

You can download the new PDF here.  The PDF posted is “preliminary” with some minor formatting and other items to be cleaned up by the fall.

Goethals Bridge – Up and out of the ground

(Post and photos provided by John Turner, Ph.D., P.E., D.GE of DBA.)

DBA has had the privilege to be the geotechnical/foundation engineer for the Goethals Bridge Replacement (GBR)Project, a design-build project for the Port Authority of New York & New Jersey (PANYNJ). The project will replace the existing Goethals Bridge that was built in the 1920s and carries I-278 over the Arthur Kill River between Elizabeth, New Jersey and Staten Island, New York.

Construction of drilled shafts continues as the superstructure begins to emerge over the skyline between Elizabeth, NJ and Staten Island, NY.  The new bridge will be a dual-span 1,983-ft long cable-stayed bridge with approach spans of over 2,500 ft on each side.  The bridge is supported on over 200 drilled shaft foundations ranging in diameter from 4.5 ft to 10 ft and socketed into Passaic Formation siltstone.

Goethals April 2016

The GBR is a Public-Private Partnership (P3) that represents a major milestone for the PANYNJ in its distinguished history of bridge building in the greater New York City metropolitan area.  The existing Goethals Bridge along with the Outerbridge Crossing and the Bayonne Bridge comprise the three Port Authority bridges connecting Staten Island with New Jersey.  The Goethals Bridge and the Outerbridge Crossing are cantilever truss structures and both opened on the same day in 1928. They were designed by J.A.L. Waddell under the supervision of the eminent engineer Othmar H. Ammann (1879-1965), who was the designer of many other iconic bridges in the NY City area including the Bayonne Bridge (1931), the George Washington Bridge (1931), and the Verrazano Narrows Bridge (1964).  The designer of record for the replacement Goethals Bridge is Parsons Corporation, which is the successor firm of Robinson & Steinman, whose principal David B. Steinman was also a notable NY area bridge designer and a contemporary and rival of O.H. Ammann.

Each main pylon tower of the GBR is supported on a group of six 9-ft diameter drilled shafts and each anchor pier is supported by two 10-ft diameter shafts.  Approach piers are two-column bents with each column supported on a rock-socketed drilled shaft.

Goethals shaft 1

DBA is the foundation design engineer of record and this project provides an example of how rock-socketed drilled shafts can provide a reliable and cost-effective means of supporting a major bridge by taking advantage of the high resistances that can be achieved.  Key factors involved in taking advantage of rock sockets for this project were:  (1) load testing to demonstrate high axial resistances (>30 ksf side resistance and  >300 ksf base resistance), (2) utilization of all relevant construction QC/QA tools to ensure that rock sockets are constructed in a manner that is consistent with construction of the load-tested shafts that provide the basis of the design, (3) close collaboration between all members of the design-build team, and (4) adequate subsurface characterization, especially a thorough characterization of rock characteristics and their effect on socket resistances. Load testing for this project demonstrates that side and base resistances can be used in combination to design rock socketed shafts for axial loading.  This approach avoids the use of unnecessarily deep sockets, thereby minimizing the associated construction risks and costs.

Goethals rendering

The GBR project developer is NYNJ Link Developer, LLC and construction is being performed by a joint venture of Kiewit-Weeks-Massman (KWM).  Parsons is the lead designer.  A construction web-cam and additional information on the GBR can be found at the Port Authority’s website: http://www.panynj.gov/bridges-tunnels/goethals-bridge-replacement.html

Kansas City Load Test Photos Added

BPU Load Test

Last spring, DBA conducted a construction phase load test program for a U.S. Army Corps of Engineers floodwall improvement project  along the Missouri River in Kansas City, Kansas.  Located on property owned and maintained by the Kansas City Board of Public Utilities (BPU), the BPU floodwall was slated for structural improvements including a series of buttresses founded on 24-in drilled shafts.  As part of the project contract a load test program performed under the direction of a qualified P.E. and D.GE was required.  General contractor L.G. Barcus & Sons, Inc., secured our Paul Axtell, P.E., D.GE as the qualified load test expert.  DBA teamed up with load testing subcontractor Applied Foundation Testing, Inc., to perform the static load tests.

The load test program requirements included three test shafts, a statically loaded axial test shaft, a statically loaded lateral test shaft, and a combined statically loaded axial and lateral test shaft.  The required combined lateral and axial test shaft provided some unique challenges with respect to applying the loads and collecting data.  As can be seen in the picture above, the axial load was applied using dead weights.

We have added selected pictures from this unique project to our web albums, which can be viewed here.

Replacing the 89 Year Old Sellwood Bridge

DBA has had the pleasure of working with T.Y. Lin and SlaydenSundt JV in their effort to replace the Sellwood Bridge over the Willamette River in Multnomah County, Oregon, near Portland. Designed by Gustav Lindenthal, the existing Sellwood Bridge was constructed in 1925 to replace the Spokane Street Ferry, connecting the communities of Sellwood and West Portland.  In response to budget issues at the time, the Sellwood Bridge design was scaled back to minimize costs. Fast forward to 2014 and the existing Sellwood Bridge is now the only four-span continuous truss highway bridge in Oregon and possibly the nation. The bridge is extremely narrow, two lanes, no shoulder or median, and one small 4-ft sidewalk.  In addition to these shortcomings in design with respect to the modern age, the west end of the bridge was constructed on fill, and the hillside above the bridge is now slowly sliding toward the river. Ground movements have caused some of the girders to crack. Furthermore, the existing bridge was not designed to any seismic standards which present a major concern given the bridge’s location in the seismically active Pacific Northwest.

The new Sellwood Bridge will be a deck arch structure with three arches supporting the deck of the main river spans and is designed to the latest seismic standards. It will feature two 12-ft travel lanes, two-12 ft shared use sidewalks, and two 6.5-ft bike lane/emergency shoulders. Multnomah County is using the existing bridge truss on temporary pile foundations as a detour to save time and money during construction with minimal impact to traffic, people can always get quick loans without credit check process at any time if they have financial problems. According to www.cyclonebuildings.com, the original bridge truss was shifted on January 19, 2013. Complicating the move was the enormity of the bridge, an 1100-ft single truss weighing 3400 tons. In addition to the size and weight of the span, old age and its curved alignment added to the technical challenges. The impressive move took only 14 hours.  The detour bridge is currently fully operational and will continue to carry traffic until the summer of 2015 when the new bridge is scheduled to open.

DBA played key roles in the design and construction of the main arch piers. As part of the VE Design, DBA assumed engineering responsibility for the 10-ft diameter drilled shafts supporting Piers 4, 5, and 6 (4 & 5 being in the river and 6 on the eastern shore).  The lengths of these shafts ranged from 81 ft to 225 ft through a number of subsurface conditions which posed many challenges to construction. Subsurface conditions ranged from large loose cobbles/gravel (Catastrophic Flood Deposits) to cemented cobbles and gravel (Troutdale Formation), to very hard intact basalt bedrock. Due to the challenging geologic conditions and variability of these conditions across the site, DBA implemented an observational method in which the final shaft length determination was made on the basis of our on-site observations in relation to a set of predefined criteria. This approach provided the necessary flexibility to efficiently confront different subsurface conditions in a timely manner. Drilling subcontractor Malcolm Drilling successfully completed construction of the last of these shafts in mid-October 2013.

You can learn more about the bridge and the project at Multnomah County’s website, SellwoodBridge.org. The website has current field work updates, photo gallery, history of the project, and a live construction camera with daily, weekly, and monthly time-lapse videos.  There is also a time-lapse of the moving of the old truss.

written by Nathan Glinski, edited by David Graham

Drilled Shafts Complete at St Croix

Pier 9 FootingAs reported by the Minneapolis Star Tribune, Case Foundation recently finished constructing 40 drilled shafts at the St Croix River Crossing Project.  Since early June, Case has been working at a feverish pace to construct the drilled shaft foundations for the new extradosed bridge between Minnesota and Wisconsin.  As of November 8th, all of the drilled shafts are officially complete.  General contractor Kramer is working to finish the pier footings and support tower bases by early 2014.  Soon, the joint venture of Lunda and Ames will begin construction of the $380 million bridge superstructure.

As MnDOT’s foundation consultant for the project, DBA has been on site during much of the foundation construction over the past five months.  Some pictures taken during this time, along with several pictures from MnDOT are available for viewing on our Picasa Page.  More pictures and information can be found on the project website and Facebook Page, and the project can be viewed live via webcam.  Previous DBA blog posts about the main project and the predesign load test program can be found here.

DBA is pleased to wrap up its role on the St Croix Crossing Project with a very positive outlook.  The drilled shaft construction proceeded on schedule and as planned without unexpected challenges, and our strong client relationships with MnDOT continued to grow stronger.  It was also nice to see familar faces from Case, Braun Intertec, and Parsons Transportation Group, many of whom we worked with us at Hastings.  We very much look forward to working with these partners again in the future!

Leo Frigo Bridge–Repair Design

The Wisconsin DOT was set to request bids this week for repairs to the Leo Frigo Memorial Bridge on I-43 in Green Bay, with an anticipated start of construction on November 4th and reopening of the bridge on January 17th.  The repair will consist of using drilled shafts installed adjacent to the existing piers with a post-tensioned extension of the pile cap to transfer the loads to the shafts.  A schematic of the design from Wisconsin DOT (via Milwaukee Wisconsin Journal Sentinel)

Scot Becker, director of the Bureau of Structures and the state’s bridge engineer, said the fix will consist of installing four concrete shafts beneath five affected piers to take over support from corroded underground steel structures, called pilings. Then, the bridge itself will be jacked up 2 feet, and concrete and steel will be poured to keep the bridge in position.

The bridge, which spans the Fox River in Green Bay, has been closed since late September, after pilings became corroded and buckled under one of the piers, causing a 400-foot-long section of the bridge to sink 2 feet. Since then, it has drooped another half inch, and the state is monitoring the bridge for further movement.

An investigation concentrating mainly in the area from Quincy St. to the Fox River found that soil surrounding the pier contained industrial byproducts over wetlands, which caused the corrosion.

Temporary supports are already being installed by Lunda to shore up the sagging spans until the repairs can be completed.

The Green Bay Press Gazette has a page archiving all of their stories, videos, photos, etc. concerning this event.

http://media.jrn.com/images/LEOFRIG23GRevise.jpg

St. Croix Bridge Construction Starts with Official Groundbreaking

St Croix Aerial Rendering

Earlier this week, officials from the Minnesota and Wisconsin departments of transportation (MnDOT and WisDOT) met for an official groundbreaking ceremony on the projected $629 million bridge and highway project that will connect Oak Park Heights, Minnesota, to St. Joseph, Wisconsin, just south of Stillwater, Minnesota, as highlighted in yesterday’s edition of The Minneapolis St. Paul Business Journal.  The new bridge will replace the 80-year-old Stillwater Lift Bridge and relieve traffic congestion in nearby Stillwater.

DBA has been retained by MnDOT as the lead geotechnical consultant and foundation designer for the extradosed river bridge.  Last summer, DBA aided MnDOT in the design and oversight of a load test program described in my blog post, “DBA Wraps Up Load Test Program and Proceeds with Design on St. Croix Bridge.”  Following final design, which took place over the fall and winter, construction of the foundations will begin next week with the installation of a technique shaft.  DBA will participate in construction as well, providing construction observation and review of the technique shaft and at least one shaft at each of the five production piers.  Edward Kraemer & Sons, Inc. of Plain, Wisconsin, has been selected as the general contractor for the foundation contract with sub-contractor Case Foundation Company of Chicago, Illinois, performing the drilling.  The extradosed bridge will feature five main river towers, each resting on two footings supported by a 4-shaft group of 8.5-foot drilled shafts, socketed 25-feet or more into sandstone bedrock.

I hope to have some more updates soon with some pictures following my upcoming site visits to observe the construction operations.  In the mean time, you can stay updated by visiting the MnDOT project page and watching the “action” live via the construction webcam.

Calibration of Resistance Factors for Drilled Shafts -A report from the LADOTD

Note: Okay – I’ll admit – I also do a blog for the Geo-Institute Deep Foundations Committee.  as such, there are often things that I feel should be posted at both – to get the widest possible audience! So, if you have already been over there, this post will look very familiar.  It is much easier to reuse a post written by yourself. – Robert

With the adoption of LRFD design methods by the American Association of State Highway and Transportation Officials (AASHTO), the Federal Highway Administration (FHWA), and most state Departments of Transportation,  the big question in the geotechnical world is “What resistance factor should we use for __________?”.  AASHTO LRFD Bridge Design Specifications provide a lot of guidance, but many in the industry are working to calibrate resistance factors to regional or local design methods and soil conditions. Various universities and state DOTs, with assistance from FHWA, National Highway Institute (NHI), and the Transportation Research Board (TRB) are conducting research projects to provide some answers to the big question (there is never just one answer in geotechnical engineering!).

Randy Post over at GeoPrac.net recently blogged about a newly released report from The Louisiana Transportation Research Center and the Louisiana Department of Transportation and Development (LADOTD) on their investigation for calibrating resistance factors for the design of axially loaded drilled shafts.  From the report abstract:

As a continuing effort to implement the LRFD design methodology for deep foundations in Louisiana, this report will present the reliability-based analyses for the calibration of the resistance factor for LRFD design of axially loaded drilled shafts using Brown et al. method (2010 FHWA design method). Twenty-six drilled shaft tests collected from previous research (LTRC Final Report 449) and eight new drilled shaft tests were selected for statistical reliability analysis; the predictions of total, side, and tip resistance versus settlement behavior of drilled shafts were established from soil borings using both 1999 FHWA design method (O’Neill and Reese method) and 2010 FHWA design method (Brown et al. method). The measured drilled shaft axial nominal resistance was determined from either the Osterberg cell (O-cell) test or the conventional top-down static load test.

You can download a PDF of the report here.