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.
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.
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.
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.
As 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!
History was made on Sept. 7, 2013when state and local officials cut the ribbon on the new Hurricane Deck Bridge during a ceremony held in the center of the new structure. The bridge officially opened to traffic in the late evening on Monday, Sept. 9. The original bridge is now closed and will be prepared for demolition during the remainder of 2013. Final demolition will take place in the spring of 2014.
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.
Lateral Statnamic test, picture by David Graham of DBA, click here for a YouTube video
DBA has been selected by MnDOT as a geotechnical and load testing consultant for the design phase load test program and foundation design of a new bridge crossing the the St. Croix River near Oak Park Heights and Stillwater, Minnesota. The new bridge will carry State Highway 36 across the St. Croix River between Minnesota and Wisconsin. Currently, Highway 36 is carried on an 80-year old two-lane vertical lift bridge in downtown Stillwater. The new bridge will divert the heavy through traffic away from the historic downtown center and reduce travel time for commuters. The iconic lift bridge will be converted to a pedestrian and bicycle only structure.
Work began this summer on the load test program which consisted of one 8-foot test shaft, two 24-inch driven steel pipe piles, and two 42-inch driven steel pipe piles, all installed in the St. Croix River along the alignment of the new bridge. Local contractor Carl Bolander & Sons Co. was selected as the general contractor for the load testing program. Bolander self-performed the installation of the test piles and sub-contracted the construction of the test shaft to Case Foundation Company, of Chicago, Illinois. Axial load testing of the test shaft was performed by Loadtest, Inc., of Gainesville, Florida, using Osterberg Cells (O-cells). Dynamic testing of the driven piles using the pile driving analyzer (PDA) was performed by local geotechnical consultant Braun Intertec. Axial testing of the driven piles and lateral testing of the shaft and one of each size pile was performed using the Statnamic Device by Applied Foundation Testing, Inc. (AFT), of Jacksonville, Florida. DBA provided pre-test recommendations, assisted MnDOT in construction oversight, provided analysis and review of the test results, and made design recommendations based on the test results.
Following the successful load test program, DBA is working with MnDOT’s structural design consultants for the project, HDR, Inc. and Buckland & Taylor Ltd. to optimize the bridge design. Already, the design team has been able to lengthen the bridge spans and eliminate a river pier as a result of the load test results, as was recently reported by Minnesota Public Radio (MPR). Also, because the total number of drilled shafts required to support the main pier towers has been reduced, construction on the foundations will been moved up to 2013 rather than the original estimated start date in 2014, also reported by MPR.
Photo Credit: Missouri Department of Transportation
I and my fellow bloggers here at DBA (David Graham and Aaron Hudson) try to keep up with the various projects under construction that we had a part of. Sometimes it is hard to do once we have left the site after foundations are complete. Modern information technology makes it much easier, especially since most large infrastructure projects have a significant public outreach effort, either by the project design/build team, or the owning agency.
In addition to the ADSC EXPO 2012 earlier in March (see post here), the annual Geo-Institute meeting for 2012, GeoCongress 2012 , was held later in the month in Oakland, California. The conference featured a very large technical program with a variety of tracks covering geotechnical engineering topics. There were also the annual named lectures (Terzaghi, Peck, etc.) and other special events. Randy Post wrote about his time at the GeoCongress at his blog, GeoPrac.net. Check out all of his posts on the conference, including photos and video.
A key feature of this congress was the State of the Art (SOA) and State of the Practice (SOP) Lectures given throughout the four days. Thirty prominent engineers were invited to give the SOA/SOP lectures. Dan gave one of the SOP lectures with his highlighting advances in drilled foundation use and selection. His paper, along with all of the other SOA/SOP lectures, is included in GSP No. 226, Geotechnical Engineering State of the Art and Practice, Keynote Lectures from GeoCongress 2012. His presentation is linked on the image below.
During the regular technical sessions, John Turner presented a paper on a recent project case history on rock-socketed drilled shaft foundations used for a bridge . His paper is in the conference proceedings volume (GSP No. 225):