All posts by David Graham

Girders go in at Hastings

photo by Jim Adams of the Minneapolis Star Tribune

Massive prestressed concrete girders, some of them setting a record for the longest concrete girders used on a Minnesota bridge, have been set at the New Hastings Bridge, currently under construction in Hastings, Minnesota.  The largest girders are 174 feet long, 8 feet tall, and weigh 108 tons!  There is a video of one of these huge beams being delivered on a 16 axle truck, below.  An article from the December 2011 issue of Concrete Products magazine about the girders can be found here.  To date, all of the girders between the north abutment and main span have been placed.  Crews are preparing piers 5 and 6 for the main span steel arches, which are scheduled to be floated in by barge and lifted into place late this year.  MnDOT has two web cams where  the bridge construction and the arch construction can be viewed. The Minneapolis Star Tribune has also been following the construction.  Their latest article, which hails the bridge as “a monumental marvel,” can be found here.

Click here for more information on our website about the New Hastings Bridge

Click here for MnDOT’s project page

Hastings Bridge Receives Press as Foundations Near Completion

As massive concrete piers rise from the Mississippi river in southeast Minnesota, people have begun to take notice of what will become the longest free-standing tied-arch bridge in North America.  A unique project in several respects, the new Hasting bridge has recently been featured in articles on the websites of ENR and Roads & Bridges.  The ENR article is a republication of an article that originally appeared in the Minneapolis Star Tribune highlighting the construction process of the last year, with particular focus on the process of constructing the river piers.  The Roads & Bridges article is a more technically in-depth piece written by the lead bridge engineer Vincent T. Gastoni, P.E., of Parsons Transportation Group.  Both articles discuss some of the many geotechnical changes faced on this project.  This excerpt from Roads & Bridges is a concise description of the pier foundations and some of the reasoning behind their selection:

The main river piers are concrete delta-style frames with the tied-arch superstructure fully framed into the pier through the knuckle connection. The stiffness of the foundation system was then integral to the overall force effects in the structure. The north pier is located in 190 ft of soft soils overlaying rock and supported on unfilled 42-in. driven steel pipe piles. Drilled shafts were investigated early but were not cost-effective, impacted the schedule and presented a risk to the existing bridge due to potential caving effects. Statnamic pile load testing was used to validate the vertical capacity and lateral performance of the 42-in. piles. The south pier footing is close to the rock surface; however, the rock was deeper, more sloped than expected, and the originally planned spread footing was changed to short drilled shafts during the final design. Dan Brown & Associates provided the team with geotechnical analysis and recommendations.

Our Tim Siegel pointed out that the statement “It’s a marvel of engineering that requires ingenious construction techniques, most of which are invisible to the drivers whizzing by overhead,” from the Star Tribune, is an accurate description of how our work as foundation designers and constructors is often viewed.  Although much of the ingenuity and innovation that goes into the geotechnical aspects of projects often goes unnoticed by the general public, it is certainly refreshing to see articles like these.  For us at DBA, it is even more refreshing to see our efforts credited by name as they were in the article by Vince when he wrote, “Dan Brown & Associates provided the team with geotechnical analysis and recommendations.”

For a design-build project with so many different geotechnical components (driven piles, drilled shafts, spread footings, retaining walls, a column-supported embankment, and light weight fill), it is hard to believe that our role as the lead geotechnical engineer is nearing completion just a little over a year after construction began.  At this point, the only foundations that have yet to be constructed are some of the rock bearing spread footings at the south approach.  DBA will also monitor instrumentation installed in the column-supported embankment for the next two years.

Previous blog posts by Aaron and David can be found here:Hastings Bridge Update and Hastings Update and Photo Album.  Additional information can be found on the DBA project page here.

Drilled Shaft Article by Dan in Geo-Strata

Constructability Considerations When Designing Drilled Shaft Foundations for Bridges

The May/June 2011 issue of ASCE’s Geo-Strata focuses on bridge geotechnics.  Dan contributed an article to this issue summarizing key constructability considerations for bridge drilled shaft designers.  Specifically, the article focuses on fresh concrete properties and reinforcement design.  Discussion of self consolidating concrete (SCC) and column-shaft connections is also included.  The article has been added to our publications page and is available through the link above.  Additional details related to bridge drilled shaft constructability can be found in the 2010 FHWA Drilled Shaft Manual here.

Dr. John Turner, P.E. joins DBA!

We are pleased to announce that John P. Turner, Ph.D., P.E., has joined our firm as a Senior Principal. Turner is Professor Emeritus, University of Wyoming, where he spent the past 25 years teaching and conducting research in geotechnical engineering. He has undergraduate degrees in both Geology and Civil Engineering and earned his doctorate in Geotechnical Engineering from Cornell University. John will bring his considerable expertise in design and construction of deep foundations to our practice. He is a co-author of the 2010 FHWA manual “Drilled Shafts: Construction Procedures and LRFD Design Methods” and the author of NCHRP Synthesis 360, “Rock-Socketed Shafts for Highway Structure Foundations”, as well as over 100 technical publications on the topics of deep foundations, earth retention, and landslide stabilization. Early in his career John was an engineering geologist with Herbert and Associates and he maintained his involvement in consulting throughout his academic career. Recent projects include design of rock-socketed drilled shafts for bridges at Pitkins Curve in Big Sur and the Antlers Bridge on I-5 in northern California. John is a recipient of the President’s Award and the Distinguished Service Award from the ADSC: International Association of Foundation Drilling. He has maintained active membership in ASCE for over 30 years and is a past chairman of the Committee on Deep Foundations of the Geo-Institute of ASCE.

Hastings Update and Photo Album

Well, I, David, have survived my first (and hopefully last) winter in Minnesota.  I spent most of January and February observing the installation of the Pier 5 drilled shafts at the new Hastings bridge project in Hastings, Minnesota.  In addition to the drilled shafts, there has been a lot activity at Hastings since Aaron last blogged about this project in January.  A link to his post is here.  All of the ground improvement piles for the column-supported embankment have been installed and approximately 75% of the caps have been poured.  The 42-inch piles and pile caps for Piers 8, 9, and 10 are also complete.  Piles for the north embankment retaining wall have been installed and construction of the wall has begun.  Excavation for the rock bearing spread footings that will support the south land piers is in progress.  Work at Piers 6 and 7 and on the north shore are currently on hold as the Mississippi River is experiencing its annual spring flood. The water level is about 14 feet above normal elevation.

I have taken the pictures Paul and I have collected over the last few months and uploaded some of the more interesting ones to a Picasa web album.  The pictures are generally in chronological order and cover most of the construction process from November of 2010 right up to the end of March 2011.  A link to our our video of a Statnamic load test at Hastings that Aaron blogged about is here.

Technical Note on ACIP Pile Load Testing

A technical note by Tim that appeared in the December 2010 issue of the DFI Journal has been added to our publications page.  Tim’s note examines some issues related to axial load testing of augered cast-in-place (ACIP) piles, also know as augercast piles or CFA piles, that are not covered in ASTM D 1143/D 1143M-07 Standard Test Methods for Deep Foundations Under Static Axial Compression.  Specifically, load hold time, unload-reload cycles, and fluctuations in incremental load are discussed as they relate to load testing for determining axial capacity or axial load distribution of ACIP piles.  Details of instrumented ACIP pile load testing are also covered.

Siegel, T.C. (2010). “Load Testing and Interpretation of Instrumented Augered Cast-in-Place Piles”, DFI Journal Volume 4, No. 2, December 2010, Deep Foundations Institute, pp69-71.

DFI requests that the following be included with all DFI papers we post:

“This paper was originally published in DFI’s bi-annual journal, Volume 4, No. 2 in December 2010.  DFI is an international technical association of firms and individuals involved in the deep foundations and related industry. The DFI Journal is a member publication. To join DFI and receive the journal, go to for further information. ”

Ownensboro Hospital Ground Improvement Project Photos and Webcam Online

Last spring, DBA designed a composite ground improvement system for a new hospital as part of the Owensboro, Kentucky, Medical Health System specializing in legal steroids, funded by roids co. Numerous medications are available to help affected people manage the infection and STD Testing Made Easy to delay or prevent progression of the illness. Tim performed most of the ground improvement design for the design-build project with Berkel & Company Contractors, Inc.  The design is a composite ground system with a layer of compacted gravel above lightly reinforced cast-in-placed displacement piles (known commercially as CGEs).  Spread foundations placed on the compacted gravel distribute the structural load to the soil and CGEs.  The construction of the composite ground system began and was completed in the summer of 2010.  The project has a designated webcam that allows the public to view the entire construction process.  The webcam can be viewed  here.  We have also uploaded some photos of construction and testing of the CGEs here.

New I-70 Bridge Featured in Foundation Drilling Magazine

The new I-70 bridge over the Mississippi River near St. Louis, Missouri is quite the project.  When completed, it will be the third longest cable-stayed bridge in the United States, with a 1,500-ft main span.  Most significantly for the geotechnical community, the bridge made history when one of its 11-ft diameter drilled shafts resisted a world record breaking 36,000 tons (bi-directional) during an O-cell load test.  The bridge has already seen press in Civil Engineering Magazine (July 2010, page 30-32), at, and in a post by Robert on this blog.  Now, an article by DBA’s Paul Axtell is featured in the September/October issue of Foundation Drilling Magazine.  The editor summarized the article saying:

The information in the following article is a composite of material that came to Foundation Drilling Magazine from three separate sources.  Part I is based on information gleaned from an article that was published on the Associated Press news wire.  Part II is excerpted from ENR’s August 18th, E-Newsletter.  Part III was provided by Paul Axtell and Dan Brown of ADSC Technical Affiliate company, Dan Brown and Associates.  The bridge project is of interest in general.  The Osterberg Load Cell test will be of particular interest to professionals in the deep foundation industry, and specifically for those who work in the drilled shaft segment.

Axtell, P.J. (2010). “Mississippi River Bridge Project Includes Record Load Test: A Three Part Story”, Foundation Drilling, Vol. 31, No. 7 September/October 2010.

Micropiles for Slope Stabilization

An article by Eric and Dan on the use of micropiles for slope stabilization has been added to our Publications Page.  Published in the August 2010 issue of Foundation Drilling Magazine, the article summarizes key findings and recommendations from a study that reviewed and evaluated existing micropile design methods.  A new design method is proposed to better predict the mobilized resistance of micropiles used for slope stabilization. The full report prepared by Eric and Dan for the joint ADSC/DFI Micropile Committee, “A Method for Predicting Mobilization Resistance for Micropiles Used in Slope Stabilization Applications”, presents the details of this study.  Robert previously posted about this report here.

Loehr, J.E. and Brown, D.A. (2010). “Design of Micropiles for Slope Stabilization”, Foundation Drilling, Vol. 31, No. 6 August 2010.