Category Archives: DBA News

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. 

NCHRP Synthesis 547 – Advancements in Use of Geophysical Methods for Transportation Projects

The Transportation Research Board (TRB) has released a synthesis report prepared by Brent L. Rosenblad and Andrew Z. Boeckmann (Andy is now with DBA) on geophysical methods for transportation projects: NCHRP Synthesis 547, Advancements in Use of Geophysical Methods for Transportation Projects.  The report is an updated summary of the state of practice with regard to geophysical methods in the transportation industry and includes a matrix of geophysical methods and applications. They conducted a survey of state DOTs and selected frequent users of geophysics to analyze “the common use methods and applications, challenges, and lessons learned.”

You can download a PDF of the report or purchase a hard copy at the link below.

Rosenblad, B.L. and Boeckmann, A.Z. (2020). NCHRP Synthesis 547, Advancements in Use of Geophysical Methods for Transportation Projects, Transportation Research Board, National Academies, Washington, D.C.

DBA Announces Officer Transitions

DBA is excited to announce recent transitions within the company.

Dan Brown, Ph.D., P.E., D.GE, is turning over the reigns of leadership to the next generation in the firm and stepping down as President.   While stepping back from day-to-day management of the company, Dan will remain fully involved in technical aspects and client service in the role of Chief Engineer where he will continue to focus on developing practical solutions to complex and challenging foundation issues.

Three Senior Principal Engineers will assume the roles of the officers of DBA.  Tim Siegel, P.E., G.E., D.GE  has been promoted to Chief Executive Officer.   Paul Axtell, P.E., D.GE has been promoted to Chief Operating Officer.  Robert Thompson, P.E., D.GE has been promoted to Chief Financial Officer.   Tim, Paul, and Robert will provide the management and leadership for the continued growth of DBA and for DBA to provide value to its clients and continue to be a key contributor to the practice of geotechnical engineering.

Tim Siegel, CEO Paul Axtell, COO Robert Thompson, CFO

 

DBA Grows – 2020 Edition!

DBA is happy to announce our two latest additions to the team: Dan Ding, Ph.D., P.E. and Andy Boekmann, Ph.D., P.E.  Dan joined us as a Project Engineer in October of 2019 while Andy came on board as a Senior Engineer in February of this year.   Read a little bit about both of them below.  Go to our About us page to see their resume as well as everyone else on the DBA Team.

Dan Ding, Ph.D., P.E.

Dan received her Ph.D. degree in Civil Engineering from the University of Missouri. Dan specializes in site characterization, geotechnical laboratory testing, Load and Resistance Factor Design, and reliability analysis. Before joining DBA, Dan worked as an adjunct assistant professor at the University of Missouri to teach undergraduate and graduate engineering courses as well as conduct national and state research projects. She also worked as a laboratory geotechnical engineer at Geocomp in Acton, MA for a year after graduation.  Dan is based in Columbia, Missouri.

Andy Boeckmann, Ph.D., P.E.

Prior to joining DBA, Andy was a research engineer at the University of Missouri, where he performed research on topics including post-grouted drilled shafts, reliability of geotechnical designs, foundation reuse, and geotechnical asset management. Andy also earned a Ph.D. at the University of Missouri; his dissertation examined the reliability of foundation designs based on site-specific load tests. Andy is the lead author of two NCHRP Synthesis reports, including Current Practices and Guidelines for the Reuse of Bridge Foundations. Prior to working at MU, Andy was a consulting geotechnical engineer for URS Corp. in St. Louis, where he performed design and analysis for large projects, including post-Hurricane Katrina levee design in New Orleans. Andy is an active member of the Deep Foundations Institute, including serving as the vice-chair of the Subsurface Characterization Committee.  He is also based in Columbia, Missouri.

2018 Tennessee Earthquake GEER Report

Tim Siegel was one of four co-leaders of a Geotechnical Extreme Events  Reconnaissance (GEER) team that investigated the impacts of the 2018 Tennessee Earthquake that occurred near Decatur, Tennessee on December 12, 2018.   Among the team members were Ali Leib and Mark Madget.  The team performed reconnaissance of the area around the epicenter of the quake and prepared a report of their observations.

The quake occurred at 4:14 am EST approximately 12 km north-northeast of Decatur, Tennessee, which is about 240 km southeast of Nashville, TN.  The highest recorded peak ground acceleration (PGA) was 0.0215g approximately 36 km from the epicenter.  At least 21 aftershocks were recorded through December 18, 2018.  The GEER team did not encounter any evidence of earthquake-induced damage in the areas they visited.  Organizations such as the Tennessee Valley Authority (TVA), the Oak Ridge National Laboratory (ORNL) , and the Tennessee Department of Transportation (TDOT) “reported that either there was no damage to their facilities or that their operations were unaffected due to earthquake.”

The team’s report can be downloaded from GEER here.  Click the image below to see the list of the entire team.

GEER is a “volunteer organization of geotechnical engineers, engineering geologists, and earth scientists from academia, industry, government organizations, and non-profit organizations.”  They assemble teams to conduct detailed reconnaissance after extreme events (earthquakes, landslides, floods, hurricanes, etc.) in order “to  obtain valuable perishable information that can be used to advance research and improve engineering practice.”

To find out more about GEER, visit their website.

Dan Brown awarded A Golden Beaver

(One more catch-up on “older” news!)

In January of 2018, Dan was awarded the coveted Golden Beaver  Award in Engineering by The Beavers.  The award was given at the 63rd Annual Golden Beavers Award Dinner on January 19, 2018 in Los Angeles.

The Beavers is a social and honorary organization organized and managed by members of the heavy construction industry.

The purpose of the Beavers is to promote goodwill, friendliness and consideration within the heavy engineering construction industry; to give recognition to those men and women who have demonstrated particular skill, responsibility and integrity; and to encourage and support entry of promising young individuals into heavy engineering construction.

The Beavers hold two major events annually. The Beavers Awards Dinner is held in mid-January, where individuals are recognized with a Golden Beaver Award for their achievements and contributions to the heavy construction industry in the categories of Management, Supervision, Engineering and Service & Supply.

Dan was honored with the award for his expertise and contributions to the deep foundations industry and its impacts on the heavy construction industry.

 

DBA is growing again – welcome to Ali, Ben, and Mark!

Well, we are at it again.  The first 5 months of 2016 have seen us add three new faces of the new website creator.  So now, drum roll, please………

Ali Leib, E.I.

Ali 2016-1

Ali was a summer intern at DBA in 2014 and 2015 and joined us full time as a staff engineer in February.  She is a recent graduate of the University of Tennessee (Go Vols!) where she completed both her B.S. and M.S. in civil engineering. While completing her M.S., she was a teaching assistant in charge of grading lab reports for the structural and geotechnical undergraduate labs. She was also a research assistant under Dr. Dayakar Penumadu, resulting in her thesis: “Effect of Particle Morphology on the Deformation Behavior of Sand under Monotonic Loading Conditions.”  Unlike most of the rest of us, Ali insists that she will not be conforming to the (mostly) standard DBA hair style.  Ali will work in our Knoxville, Tennessee office.

Mark Madgett, P.E.

Mark Madgett_s

 

Mark received a BS and MS degree in Civil Engineering at the University of Tennessee, while working on research for TDOT to improve pavement design methods.  He has worked in both consulting and construction for the last 22 years, focusing primarily on deep foundations in the Southeastern US.  As a consultant, Mark gained extensive field experience with deep foundation construction techniques and the impacts on design.  In 2006, he began working for Seaboard Foundations, opening a green field office in Tri-Cities TN as the district manager.  In his role as design engineer for Seaboard Foundations, Mark has implemented design-build techniques in many markets (energy, institutional, commercial, transportation, and healthcare you can supplement if you find Kratom online and other natural products) that vastly improved the constructability and reduced the costs of deep foundation systems for his clients.  Mark will also work outr of our Knoxville, Tennessee office.

Ben Turner, Ph. D., P.E.

Ben recently completed his Ph.D. in geotechnical earthquake engineering at UCLA with an emphasis on the transfer of forces between the ground and foundation elements during seismic loading. Prior to starting at UCLA, he worked for two years for the Los Angeles office of Shannon & Wilson, Inc.  Ben worked in both construction and geotechnical firms while attending school for his B.S. and M.S. degrees. His experience includes: design, construction, and load testing of deep foundations;  geotechnical earthquake engineering including soil-structure interaction, seismic hazard analysis, site response, liquefaction triggering analysis and mitigation of liquefaction-induced ground failure; and, characterization of structural behavior of reinforced concrete foundations.  Here are two of the publications resulting from his dissertation work:

Turner, B., Brandenberg, S., and Stewart, J. (). “Case Study of Parallel Bridges Affected by Liquefaction and Lateral Spreading.” J. Geotech. Geoenviron. Eng. , 10.1061/(ASCE)GT.1943-5606.0001480 , 05016001.

Turner, B. and Brandenberg, S. (2015) “Pile Pinning and Interaction of Adjacent Foundations During Lateral Spreading”, DFI Journal, Volume 9, Issue 2.

Ben will anchor the West Coast Region of DBA, working from San Luis Obispo , California.

 

New PEER Report – Evaluation of Collapse and Non-Collapse of Parallel Bridges Affected by Liquefaction and Lateral Spreading

webPEER-2014-10-Brandenberg

Our own Ben Turner (future Dr. Turner!) was lead author on a report by the Pacific Earthquake Engineering Research Center (PEER) on liquefaction and lateral spreading effects on bridges. The report is titled “Evaluation of Collapse and Non-Collapse of Parallel Bridges Affected by Liquefaction and Lateral Spreading”. Ben’s coauthors are Dr. Scott J. Brandenberg and Dr. Jonathan P. Stewart of the Department of Civil and Environmental Engineering at UCLA. From the abstract:

The Pacific Earthquake Engineering Research Center and the California Department of Transportation have recently developed design guidelines for computing foundation demands during lateral spreading using equivalent static analysis (ESA) procedures. In this study, ESA procedures are applied to two parallel bridges that were damaged during the 2010 M 7.2 El Mayor-Cucapah earthquake in Baja California, Mexico. The bridges are both located approximately 15 km from the surface rupture of the fault on soft alluvial soil site conditions. Estimated median ground motions in the area in the absence of liquefaction triggering are peak ground  accelerations = 0.27g and peak ground velocity = 38 cm/sec (RotD50 components). The bridges are structurally similar and both are supported on deep foundations, yet they performed differently during the earthquake. A span of the pile-supported railroad bridge collapsed, whereas the drilled-shaft-supported highway bridge suffered only moderate damage and remained in service following the earthquake. The ESA procedures applied to the structures using a consistent and repeatable framework for developing input parameters captured both the collapse of the railroad bridge and the performance of the highway bridge. Discussion is provided on selection of the geotechnical and structural modeling parameters as well as combining inertial demands with kinematic demands from lateral spreading.

This report is part of Ben’s work on his doctoral dissertation. You can download the report by clicking on the linked citation below.

Turner, B., Brandenberg, S.J. and Stewart, J.P. (2014). “Evaluation of Collapse and Non-Collapse of Parallel Bridges Affected by Liquefaction and Lateral Spreading”, PEER Report 2014/10, Pacific Earthquake Engineering Research Center, University of California, Berkley, August, 2014, 94pp.

DBA Expands Again – Welcome Rob Saunders, P.E. and Ben Turner, P.E.!

DBA is please to announce the addition of two new members: Robert M. Saunders, P.E. and Benjamin Turner, P.E.

14_Rob S

Rob is a graduate of the University of Tennessee (BSCE and MSCE) with 11 years of experience. He began his career at S&ME working with our own Tim Siegel and for the last 8 years has been with GEOServices, LLC in Knoxville. He has a broad design background, specializing in analysis and design of earth retention systems and deep foundations. His experience with earth retention systems includes design and construction of soil nail walls, soldier pile walls, anchored systems, temporary shoring, and mechanically stabilized earth walls. His experience with deep foundation design includes lateral response analysis of deep foundations and design of deep foundation in karst geology. Rob has been involved with several major projects for private companies and public agencies including Foothills Parkway in Blount co., Tennessee, Interstate 240 expansion in Memphis, Tennessee, and Bridgeforth Stadium at James Madison University.

Rob will be located in Knoxville, Tennessee with Tim Siegel.

 14_Ben

Ben is currently pursuing a Ph.D. in geotechnical earthquake engineering at UCLA with an emphasis on the transfer of forces between the ground and foundation elements during seismic loading. Prior to starting at UCLA, he worked for two years for the Los Angeles office of Shannon & Wilson, Inc.  Ben worked in both construction and geotechnical firms while attending school for his B.S. and M.S. degrees.  His experience includes: design, construction, and load testing of deep foundations;  geotechnical earthquake engineering including soil-structure interaction, seismic hazard analysis, site response, liquefaction triggering analysis and mitigation of liquefaction-induced ground failure; and, characterization of structural behavior of reinforced concrete foundations.

Ben will be working part-time as he can while completing his Ph. D. and will  join DBA full time after completing his studies, staying in the Los Angeles, California area.

 

Welcome to both Rob and Ben!