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43rd ANNUAL FHWA MIDWEST GEOTECHNICAL CONFERENCEBloomington, MINNESOTA, OCTOBER 1-3, 2014
State of Practices in Databases for Deep Foundations Load Tests
Dr. Naser Abu-Hejleh, FHWA Resource Center
Dr. Murad Abu-Farsak, Louisiana State University
Dr. Muhannad T. Suleiman, Lehigh University
Dr. Ching Tsai, Louisiana DOT
.
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Presentation Goals
Help State DOTs and their researchers/consultants to:
Use foundation load test databases
Benefit from existing foundation load test databases
Develop quality foundation load test databases
More accurate and economical foundations geotechnical design
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Presentation Outline
1. Applications of foundation load test databases
2. Contents and use of:
FHWA Deep Foundation Load test Database
Other Deep Foundation Load Test Databases
3. Recommendations
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Types of Methods to Determine Foundations Geotechnical Resistance & Displacement
1. Full-scale static load test: most accurate method
2. Simple prediction methods (analytical expression):
Static analysis (α- and β- methods)
Soil/rock design properties (e.g., Rn= 2.5Abqu)
Dynamic analysis (dynamic load test; formula)
Driving records and hammer/soil information
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Load Test: Direct Measurements of
Foundations Resistance/Displacements
0
5
10
15
20
25
30
0 1 2 3
Top
Defl
ect
ion
(mm
)
Axial Load, Q (MN)
Qtotal = Qs + Qb
Pred. Qs
Pred. Qb
Meas. Total
Meas. Shaft
Meas. Base
Load test data can be used to develop more accurate/economical simple design methods
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How Foundation Load Test Data Can Be Used?
1. In the individual projects they are used in to:
Optimize and/or verify the geotechnical design
2. Above and in the future to improve the simple
geotechnical design methods. Needs:
Quality and complete data
Document the data (databases)
Minimal extra efforts compared to the benefits!
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Instrumented and proof Load test: Procedure, direction & results (load-settlement curve)
Test foundation: type, layout,
dimensions, construction, quality control
Soil/rock around the test foundation:
Design properties and the procedure
to obtain them.
Foundations Load Test Database = Quality and Complete Data at Load Test Sites
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Analysis of Load Test Databases
For a group of test foundations, evaluate & compare:
Measured resistance/displacement from load test
Predicted resistance/displacement from the simple
design methods that will be evaluated.
Similar design and construction conditions for test and
production foundations
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Applications of Foundation Load Test Databases
By Designers: perform more accurate and economical
design for production foundations in their projects
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Applications of Foundation Load Test Databases
By Researchers: reliability calibration of various
(AASHTO, local, new) design methods:
Develop resistance factors
Identify/develop more accurate and economical:
Simple design methods
Testing methods to determine soil/rock properties
Methods for construction and quality control
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This requires databases that include:
Quality and complete load test records
Statistically adequate to cover the common design
and construction conditions in the US
Local databases are needed:
Accounts for specific design/construction
conditions (more economical/accurate)
For methods not calibrated in AASHTO
Future: Reliability-Based Foundation Geotechnical Design Methods
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FHWA Deep Foundation Load Test Database (DFLTD)
Most comprehensive and largest database 1307 load tests collected during 1985-2003
Load transfer results for 21 test foundations
Used to develop other databases (discussed later)
Limitations: Missing and limited information
Distribution: contact FHWA (Dr. Naser Abu-Hejleh)
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FHWA DFLTD Information
State # of Load Tests
State # of Load Tests
State # of Load Tests
California 327 Louisiana 245 Florida 163Mississippi 98 Texas 37 New York 36
Arizona 35 Pennsylvania 24 Hawaii 23South Carolina 19 Nevada 18 Colorado 11Massachusetts 11 Washington 10 New
Mexico8
Boring Data Lab Data SPT CPT PMT
723 752 971 275 75
Cohesive Non-Cohesive Variable Rock s IGM
119 263 715 978
Location by States
Subsurface Investigation
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FHWA DFLTD Information
Pile Types
Drilled Shafts
Pile: Square
Concrete
Pile: Round
Concrete
Pile: Steel H-
pile
Pile: Timber
Pile: Step Tapered
Open Pipe Pile
371 356 175 104 62 60 51Screw Pile (3), Micropile (4), Monotube (18), Auger cast (9), Composite (13), Franki (10)
Type of LoadsCompression Tension Lateral
1132 67 44Type of Load Tests
Standard Quick Osterberg Statnamic692 394 24 131
Other CriteriaCyclic To Failure CAPWAP
109 712 113
Load Test
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FHWA DFLTD Information
Construction Methods for Drilled ShaftsDrilled
and Grouted
Dry Wet
with Bentonite
Wet with
Casing Left
Wet with Casing
Withdrawn
With Polymer Slurry
Wet Water only
Cast-in-
Place
N/A
17 128 5 73 22 24 36 25 41
Construction Methods for Driven PilesImpact Driven
Mandrel Driven Concrete Filled
Vibrated Screw Pile
Jacked Vibrated and Driven
N/A
601 42 27 2 4 1 8
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Other Deep Foundation Databases
PD/LT2000 (NCHRP Report 507, 2004 )
AASHTO’s LRFD resistance factors ()
Washington dynamic formula
for drilled shafts (Ohio, 2012)
New Mexico (2012)
24 drilled shaft load tests in granular soils
Resistance factors () for side resistance methods
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Deep Foundation Databases
PSU for Driven Piles (Oregon, 2010).
Identified quality data from DFLTD and applicable to
Oregon practices
= 0.5 for wave equation analysis at EOD/BOR
for different combinations of pile and soil types
California
Has a large number of load tests, archived in the web
On-going research study
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Deep Foundation Databases
Florida DOT (FDOT):
Long history in development of databases
Deep Foundation Database
627 load tests in Access database
Online database (100 load tests)
Local load test data
FDOT for driven piles and drilled shafts
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Deep Foundation Databases
International Database (Long, 2009)
Illinois:
Evaluation of various static/dynamic analysis methods
Identified/developed the best methods
Updated Illinois DOT design specifications
Wisconsin: Evaluation of 5 dynamic analysis methods
and identified the best method
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Deep Foundation Databases
Pilot & DSHAFT Iowa online databases (2010-2011)
Local data
Driven piles (275) and drilled shafts (38)
for driven piles:
Larger than AASHTO
Smaller than with calibration by fitting to ASD
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Deep Foundation Databases
Louisiana Load Tests (2008, 2012)
Driven piles (53) and drilled shafts (26)
Local load tests
larger than AASHTO
Calibrate design methods not used in AASHTO
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Recommendations
1. Develop a national protocol to obtain and report
quality and complete new data at load test sites:
Consistent procedure to obtain data: Follow AASHTO/FHWA procedures Consider local and new/better procedures
Report consistent data using similar: “Foundation Load Test Record Form” Guide: describe the data and the procedure to obtain
them
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Recommendations
2. Identify and compile existing quality load test
data that were not documented
3. Deploy quality format and facilitate distribution
Consistent format with the national protocol
Flexibility to update, expand, modify, and access
Appealing user friendly interface to filter, sort, query,
and generate the needed information.
Long-term management and maintenance
Online databases
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Recommendations
4. Develop quality and complete:
Local databases by states Using their data and data of others appropriate to
their design/construction conditions
Regional databases Of states with similar design/construction conditions
National databases: Bank for other states!!
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Recommendations- Implementation
Collaboration between Public and Private
Highway Engineering Agencies
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Questions?
Will e-mail you:
FHWA Deep Foundation Load Test Database (DFLTD)
2010 NHI Manual: “Implementation of LRFD
Geotechnical Design for Bridge Foundations”
Relevant Papers
2013 FHWA Report: “Implementation of AASHTO LRFD
Design Specification for Driven Piles.”
Dr. Naser Abu-Hejleh, P.E.FHWA Resource Center
[email protected]; (708) 283-3550