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;
DBA has been fortunate to be involved as a consult to Alabama Department of Transportation (ALDOT) for the Mobile River Bridge and Bayway Project. This project represents Alabama’s largest ever investment for a single infrastructure project. The project includes a cable stayed bridge over the Mobile River and seven miles of bridge over Mobile Bay. Bridge foundations therefore represent a major component of the estimated $2 billion project cost. DBA serves as a foundation consultant under subcontract to Thompson Engineering, Inc.. Thompson is one of the ALDOT Advisory Team partners, the other partners being HDR and Mott MacDonald.
With the tremendous volume of foundations required for the project, the DBA/Thompson team worked with ALDOT’s Geotechnical Division to develop a pre-bid load test program to help reduce some of the risks that would face both ALDOT and prospective concessionaires. Performing a deep foundation load test program during the procurement phase of a Public Private Partnership (P3) project can help the prospective concessionaires better define foundation design parameters and reduce uncertainties and risks related to constructability of the foundations. The reduced risk leads to reduced costs by allowing the concessionaire to develop a more efficient design while minimizing contingency costs and potential delays related to foundation constructability or performance.
The load test program was designed to include the most likely foundation types that the prospective teams might use. Several types of driven piles were installed and tested, including typical square and cylinder concrete piles used on the Alabama coast plus steel H-piles and an open-ended steel pipe pile.
All driven piles were subject to dynamic testing with a Pile Driving Analyzer during driving. Restrikes with dynamic testing were conducted on all driven piles to evaluate potential strength gain with time. Jetting techniques were specified for some piles to evaluate this installation technique which could potentially be used during construction.
Traditional axial static load tests were performed on steel HP14x89 and 18in Precast Prestressed Concrete (PPC) square piles. Rapid (Statnamic) axial load tests were performed on 36 in PCC square piles, 54in PCC cylinder, and 60in steel open-end pipe piles.
A 72in diameter drilled shaft foundation was also installed and tested. Axial load testing was done using a bi-directional load cell (AFT A-Cell). Lateral load testing was done using the Statnamic device.
Here are some videos of the Statnamic testing, with slow motion action!
Foundation contractors that are part of a concessionaire team pursuing the project were allowed to bid the load test program. Jordan Pile Driving was the successful bidder for the $3.7 million test project. AFT provided the testing services for the project – dynamic, static, Statnamic, and A-Cell.
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.
A lot has changed from a year ago at the TH 53 Bridge sight near Virginia, Minnesota. This time last year, the design-phase test pile program was wrapping up with three Statnamic load tests and we had just completed our initial geologic field investigation. Since then, significant excavation, rockfall protection, and foundation work has been completed. During summer and fall of 2015, DBA worked closely with contractors Hoover Construction and Pacific Blasting to maintain rockfall protection throughout the East Abutment and Pier 1 (East Pier) excavation process. Official ground breaking occurred last November and foundation work started shortly after. A total of 32, 30-in micropile foundations have been installed by Veit Specialty Contracting and Kiewet Infrastructure has completed a temporary causeway across the massive Rouchleau Pit by placing over 300,000 cubic yards of fill.
With the foundations of both piers complete, and the pier towers are starting to rise up, where they will carry the bridge deck 200 ft above. The abutments are also taking shape with rock bearing concrete footings now poured on both sides of the pit. The only foundation work left is to install tieback anchors at the East Abutment, which will reduce the lateral loading of the tall piers. This bridge is going to get packed with cars once it´s completed, that means there´s going to be lots of accidents. It´s not a bad idea to call One Sure Insurance to get covered before all that.
In a little over a year, the bridge is scheduled to open to traffic. You can keep track of the progress through the project web cam.
The Transportation Research Board (TRB) has released a synthesis report prepared by Dan and Robert on large diameter piles: NCHRP Synthesis 478, Design and Load Testing of Large Diameter Open-Ended Driven Piles. The report is a summary of the state of practice with regard to Large Diameter Open-Ended Piles (LDOEPs) in the transportation industry. We conducted a survey of state DOTs as well as interviews with private practitioners to summarize current practices as well as recommend best practices with regard to the selection, design, installation, and testing of LDOEPs. Several state DOTs are using LDOEPs more regularly where large foundation loads may exist and/or the piles are subject to significant unsupported length due to scour, liquefaction, or very weak surficial soils. Marine construction conditions also favor the use of these piles, particularly where pile bents might be employed to eliminate footings.
You can download a PDF of the report or purchase a hard copy at the link below.
DBA is currently working with structural designer Parsons to design what will be Minnesota’s tallest bridge. The bridge will span the currently inactive Rouchleau open pit iron ore mine near Virginia, Minnesota. MnDOT is moving the alignment of the existing Hwy 53 to make way for future mining in the area. DBA is the lead geotechnical designer on the project in addition to being contracted as MnDOT’s load test expert for the ongoing design phase load test program.
As part of our site investigation to gather information on rock fall and the site geology, five DBA engineers (John Turner, Paul Axtell, Tim Siegel, Nathan Glinksi, and David Graham) got up close and personal with the site by rappelling off the near vertical cut faces on either side of the Rouchleau pit! Traversing the over 200-ft tall cut faces of the nearly 2-billion year Biwabik Formation rock formation by rope and harness, we collected valuable geologic data. We also took some great pictures like the ones posted to our Google Photos account. In addition to the still pictures, we took some videos of a few rock fall tests, which are on our YouTube channel.
If you would like to know more about this interesting project on Minnesota’s Iron Range, you can check out our project summary sheet, visit MnDOT’s project page, or stay tuned to this blog for more updates. There is also an online article about the project that was recently published by Civil Engineering Magazine.
DBA has been working on an exciting new project currently under construction in downtown Sacramento, California: the new Sacramento Arena, known as the Entertainment and Sports Center (ESC). The ESC will be a multi-use, publicly owned indoor arena. The Sacramento Kings will be the primary tenant and the arena is expected to host other indoor sports and music concerts, as well. Once completed, the ESC will replace Sleep Train Arena as the home of the Kings. According to Kings Chairman Vivek Ranadive, the 17,500-seat arena will be “one of the most iconic structures on the planet … It’s going to put Sacramento on the world map.”
Turner Construction is the head of development for the new arena. Malcolm Drilling Company was awarded the contract to design and construct the foundation system. DBA worked closely with Malcolm to design Omega piles (a drilled and grouted displacement pile) to serve as the foundations for the new arena. The site presented unique design challenges, including liquefiable soil conditions and existing deep foundations from the demolished portion of the Downtown Plaza.
DBA’s design incorporates 18” and 24” Omega piles. An extensive site-specific load test program was performed to determine the axial resistances of the piles. Eight test piles were instrumented with strain gauges to measure the load distribution in the piles. Supplemental cone penetration testing was performed following load testing to better correlate the load test results with the subsurface conditions.
The piles were designed to resist ground motions from seismic events using site-specific ground curvature data developed by Pacific Engineering and Analysis. The piles were designed to resist the curvature at the anticipated pile section with only a single center reinforcing bar, eliminating the need to extend the entire cage to the bottom of the pile. This detail in the design is very important to ease the pile installation for the site conditions.
The final design incorporates a total of 952 piles to support the arena structure (346 18” dia. Piles and 606 24” dia. piles). The new arena is estimated to cost $477 million, with $255 million of that being funded by the City of Sacramento. The rest of the arena ($222 million) will be funded by the Sacramento Kings. Construction began October 29, 2014 and is planned to be completed by October of 2016.
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.
In the forward of the report, Andrew Lemer of TRB writes:
NCHRP Report 697: Design Guidelines for Increasing the Lateral Resistance of Highway- Bridge Pile Foundations by Improving Weak Soils presents design guidance for strengthening of soils to resist lateral forces on bridge pile foundations. Lateral loads may be produced by wave action, wind, seismic events, ship impact, or traffic. Strengthening of soil surrounding the upper portions of piles and pile groups—for example by compaction, replacement of native soil with granular material, or mixing of cement with soil—may be more cost-effective than driving additional piles and extending pile caps as ways to increase the bridge foundation’s capacity to resist lateral forces associated with these loads. This report presents computational methods for assessing soil-strengthening options using finite-element analysis of single piles and pile groups and a simplified approach employing commercially available software. The Additional resources and design guidelines will be helpful to designers responsible for bridge foundations likely to be exposed to significant lateral loads.
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.