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 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.
In the course of digging throughout the internet for data and information for a couple of projects using one of the best wifi routers, I came across some (relatively) recent research reports geared toward improving design of driven piles based on field testing. A report from The Illinois Center for Transportation at the University of Illinois at Urbana-Champaign is focused on improving pile design through increased resistance factors and nominal bearing values. A project by the Institute for Transportation at Iowa State University focuses on developing LRFD design procedures for steel piles in Iowa. It was published in two volumes, with Volume I covering the development of LRFD calibrations and a load test database, and Volume II covering field load tests performed for the project.
I have not had time to dig into them yet, so I just offer the links and abstracts to pique your curiosity. Perhaps you may find something interesting in them, or maybe something applicable to a project. There is a lot of research going on out there for TRB and NHI, so I figure sharing interesting tidbits helps get things circulated.
Click on the name of each of the research centers above to find out what other things they are doing, available reports, etc.
Dynamic pile testing and one static load test was performed in accordance with ICT project R27-69, “Improved Design for Driven Piles Based on a Pile Load Test Program in Illinois.” The objectives of this project are to (1) increase the maximum nominal required bearing that designers can specify to reduce the number and/or weight of piles, (2) decrease the difference between estimated and driven pile lengths to reduce cutoffs and splice lengths by development of local bias factors for predictive methods used in design, (3) increase reliance of pile setup to increase the factored resistance available to designers, (4) reduce the risk of pile driving damage during construction, and (5) increase the resistance factor (decrease in factor of safety) based on increased data and confidence from load tests in and near Illinois. Project deliverables can be categorized as (1) better prediction methods for stresses during driving, (2) better prediction methods for pile capacities using resistance factors for driven piling based on local calibrations that consider the effects of pile setups, and (3) collections of static and dynamic load test data focused on Illinois soils and geology.
For well over 100 years, the Working Stress Design (WSD) approach has been the traditional basis for geotechnical design with regard to settlements or failure conditions. However, considerable effort has been put forth over the past couple of decades in relation to the adoption of the Load and Resistance Factor Design (LRFD) approach into geotechnical design. With the goal of producing engineered designs with consistent levels of reliability, the Federal Highway Administration (FHWA) issued a policy memorandum on June 28, 2000, requiring all new bridges initiated after October 1, 2007, to be designed according to the LRFD approach. Likewise, regionally calibrated LRFD resistance factors were permitted by the American Association of State Highway and Transportation Officials (AASHTO) to improve the economy of bridge foundation elements. Thus, projects TR-573, TR-583 and TR-584 were undertaken by a research team at Iowa State University’s Bridge Engineering Center with the goal of developing resistance factors for pile design using available pile static load test data. To accomplish this goal, the available data were first analyzed for reliability and then placed in a newly designed relational database management system termed PIle LOad Tests (PILOT), to which this first volume of the final report for project TR-573 is dedicated. PILOT is an amalgamated, electronic source of information consisting of both static and dynamic data for pile load tests conducted in the State of Iowa. The database, which includes historical data on pile load tests dating back to 1966, is intended for use in the establishment of LRFD resistance factors for design and construction control of driven pile foundations in Iowa. Although a considerable amount of geotechnical and pile load test data is available in literature as well as in various State Department of Transportation files, PILOT is one of the first regional databases to be exclusively used in the development of LRFD resistance factors for the design and construction control of driven pile foundations. Currently providing an electronically organized assimilation of geotechnical and pile load test data for 274 piles of various types (e.g., steel H-shaped, timber, pipe, Monotube, and concrete), PILOT (http://srg.cce.iastate.edu/lrfd/) is on par with such familiar national databases used in the calibration of LRFD resistance factors for pile foundations as the FHWA’s Deep Foundation Load Test Database. By narrowing geographical boundaries while maintaining a high number of pile load tests, PILOT exemplifies a model for effective regional LRFD calibration procedures.
In response to the mandate on Load and Resistance Factor Design (LRFD) implementations by the Federal Highway Administration (FHWA) on all new bridge projects initiated after October 1, 2007, the Iowa Highway Research Board (IHRB) sponsored these research projects to develop regional LRFD recommendations. The LRFD development was performed using the Iowa Department of Transportation (DOT) Pile Load Test database (PILOT). To increase the data points for LRFD development, develop LRFD recommendations for dynamic methods, and validate the results of LRFD calibration, 10 full-scale field tests on the most commonly used steel H-piles (e.g., HP 10 x 42) were conducted throughout Iowa. Detailed in situ soil investigations were carried out, push-in pressure cells were installed, and laboratory soil tests were performed. Pile responses during driving, at the end of driving (EOD), and at re-strikes were monitored using the Pile Driving Analyzer (PDA), following with the CAse Pile Wave Analysis Program (CAPWAP) analysis. The hammer blow counts were recorded for Wave Equation Analysis Program (WEAP) and dynamic formulas. Static load tests (SLTs) were performed and the pile capacities were determined based on the Davisson’s criteria. The extensive experimental research studies generated important data for analytical and computational investigations. The SLT measured loaddisplacements were compared with the simulated results obtained using a model of the TZPILE program and using the modified borehole shear test method. Two analytical pile setup quantification methods, in terms of soil properties, were developed and validated. A new calibration procedure was developed to incorporate pile setup into LRFD
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.
Guideline for Interpretation of Nondestructive Integrity Testing of Augered Cast-in-Place and Drilled Displacement Piles
DFI Augered Cast-In-Place Pile Committee (2011-2012) Chaired by Michael Moran
Tracy Brettmann, Principal Author; Bernard Hertlein, Matthew Meyer, Bria Whitmire, Co-Authors
(Image from DFI)
This guideline provides practical guidance for the interpretation of nondestructive testing (NDT) of the integrity of augered cast-in-place (ACIP) and drilled displacement (DD) piles. … This guideline supplements DFI’s two primary publications on ACIP piles: Augered Cast-in-Place Pile Manual (2003) and the Inspector’s Guide for Augered Cast-in-Place Piles (2010). This guideline was developed to provide 1) more detailed explanations of the various test methods available, 2) guidance on interpretation of the results, and 3) some typical examples of the data and interpretation.
Seismic and Lateral Load Design and Testing Guidelines
DFI Seismic and Lateral Loads Committee (2011-2012)
Chaired by Mark Petersen and Zia Zafir (2003-2009)
Robert Kruger, Guideline Editor
This guidance document is intended to assist geotechnical engineers, pile designers, and contractors in analysis, design, and testing of piles and drilled shafts for lateral loads. … … This document discusses the background of different analytical and testing procedures and presents the recommended methods for analysis, design and testing of piles for lateral loads.
We have added Mike Holloway’s presentation at DFI SuperPile 2012 on May 17, 2012 to our Presentations Page. Mike discussed some of the issues related to pile testing and what can influence the blow counts that are often relied upon to accept piles. He covered the types of testing, limitations of various methods, and issues to consider when applying test results to production piling.