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San Francisco Millennium Tower Has Settled 16 Inches
Misrepresents actual foundation geometry. Photos show deep excavation to ne
New FHWA Soil Nail Manual Addresses LRFD, Hollow Bars
Good evening from Barcelona, Spain. I am witting to you because of I am le
Engineering Geologists vs Geological Engineers vs Geotechnic
Geological engineer from Spain (looking for job smiley geoengineer.martin@gmail
A Whole Lotta Shakin' Goin' On: Center for Geotechnical Mode
Randy, While the UC Davis lab is impressive I believe the USACE Centrifuge
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Standards and Codes
Calibration of Resistance Factors for Drilled Shafts for the New FHWA Design Method PDF Print E-mail
Written by Randy Post   
Wednesday, 20 March 2013 00:16
Probability of failure

The Louisiana Transportation Research Center has released a report that presents the reliability-based analyses for the calibration of the resistance factor for load and resistance factor design of axially loaded drilled shafts. Here is the abstract:

The Load and Resistance Factor Design (LRFD) calibration of deep foundation in Louisiana was first completed for driven piles (LTRC Final Report 449) in May 2009 and then for drilled shafts using 1999 FHWA design method (O’Neill and Reese method) (LTRC Final Report 470) in September 2010. As a continuing effort to implement the LRFD design methodology for deep foundations in Louisiana, this report will present the reliability-based analyses for the calibration of the resistance factor for LRFD design of axially loaded drilled shafts using Brown et al. method (2010 FHWA design method). Twenty-six drilled shaft tests collected from previous research (LTRC Final Report 449) and eight new drilled shaft tests were selected for statistical reliability analysis; the predictions of total, side, and tip resistance versus settlement behavior of drilled shafts were established from soil borings using both 1999 FHWA design method (Brown et al. method) and 2010 FHWA design method (O’Neill and Reese method). The measured drilled shaft axial nominal resistance was determined from either the Osterberg cell (O-cell) test or the conventional top-down static load test. For the 30 drilled shafts that were tested using O-cells, the tip and side resistances were deduced separately from test results. Statistical analyses were performed to compare the predicted total, tip, and side drilled shaft nominal axial resistance with the corresponding measured nominal resistance. Results of this showed that the 2010 FHWA design method overestimates the total drilled shaft resistance by an average of two percent, while the 1999 FHWA design method underestimates the total drilled shaft resistance by an average of 21 percent. The Monte Carlo simulation method was selected to perform the LRFD calibration of resistance factors of drilled shaft under strength I limit state. The total resistance factors obtained at different reliability index (Beta) were determined and compared with those available in literature. Results of reliability analysis, corresponding to a target reliability index (Beta) of 3.0, reveals resistance factors for side (Phi-side), tip (Phi-tip), and total resistance factor (Phi-total) are 0.26, 0.53, and 0.48, respectively for the 2010 FHWA design method and 0.39, 0.52, and 0.60, respectively for the 1999 FHWA design method. The side and total resistance factors calibrated using the 2010 FHWA design method are less than those calibrated using the 1999 FHWA design method.
[Source: TRB Geotechnology. Image: ScienceDirect.com]

 
ASTM Updates for October 2012 PDF Print E-mail
Written by Randy Post   
Friday, 09 November 2012 06:26

American Society of Testing Materials Logo - ASTMHere is a collection of new, revised and updated ASTM standards from October 2012 that may be of interest to geoprofessionals.  See the list after the break...

 
New FEMA Document on Hydrologic Dam Safety PDF Print E-mail
Written by Randy Post   
Sunday, 14 October 2012 23:00

FEMA Report: Summary of Existing Guidelines for Hydrologic Safety of DamsFEMA has recently released a new document titled “Summary of Existing Guidelines for Hydrologic Safety of Dams”.  I was pleased to hear about this report from one of it’s co-authors, Amanda Hess of Gannett Fleming.  Amanda was a colleague of mine in ASFE Fundamentals of Professional Practice (FOPP) Course No. 21.  Here is Amanda’s synopsis of the document:

The document provides a nice history of the evolution of design flood selection for spillways, a description of the origins of dam safety guidelines and a summary of the current state of the practice.  As part of our research, we surveyed dam safety representatives from all 50 states as well as Puerto Rico with the exception of Alabama and Florida.  We also surveyed most of the federal agencies that are involved with dam safety.

She also indicated that the next step will be a subsequent report containing new hydrologic safety guidelines that will could be applied nationwide.  We’ll keep our eye out for the new report sometime in 2013. 

Last Updated on Sunday, 14 October 2012 23:05
 
ASTM Updates for August 2012 PDF Print E-mail
Written by Randy Post   
Monday, 17 September 2012 23:06

American Society of Testing Materials Logo - ASTMI've collected a list of new, updated and otherwise updated ASTM standards that pertain to geotechnical engineering, construction and materials testing and laboratory testing of soil, rock, geosynthetics and related fields.  This month's updates contains a new standard for measuring hydraulic conductivity of recycled tire-derived aggregate, updates to leak detection standards and more.  Click through for the list of updates to ASTM standards you can't afford to ignore in your practice.

 
ASTM Updates for June and July 2012 PDF Print E-mail
Written by Randy Post   
Monday, 30 July 2012 12:41

American Society of Testing Materials Logo - ASTMThis post contains a list of new, revised and otherwise updated ASTM standards that pertain to the geotechnical engineering, materials testing and related fields. The standards for the standard proctor and modified proctor tests have been revised.  There are a number of updated standards associated with cements and mortars, and curiously several standards that have been withdrawn with no replacements, including the standard for testing collapse susceptibility of soils, one pertaining to curing of concrete, and two for testing of soil-cement mixtures.  Click through to see the updates to the ASTM standards.

 
Geoengineering ASTM Updates for May, 2012 PDF Print E-mail
Written by Randy Post   
Monday, 11 June 2012 12:58

American Society of Testing Materials Logo - ASTMGeotechnical engineers, geotechnical lab managers, CQA service managers and others utilize ASTM standards on a daily basis.  Here at GeoPrac.net, we monitor the periodic updates from ASTM and summarize changes to relevant standards that may be of interest to geoprofessionals.  Click through for a list of revised and reapproved standards from May of 2012.

 
ASTM Updates for April 2012 PDF Print E-mail
Written by Randy Post   
Tuesday, 08 May 2012 21:07

American Society of Testing Materials Logo - ASTMHere is a collection of new, revised and updated ASTM standards from April 2012 that may be of interest to geoprofessionals.  See the list after the break...

Last Updated on Tuesday, 08 May 2012 21:46
 
ASTM Updates for March, 2012 PDF Print E-mail
Written by Randy Post   
Monday, 16 April 2012 12:47

American Society of Testing Materials Logo - ASTMThis post contains a list of new, revised and otherwise updated ASTM standards that pertain to the geotechnical engineering, materials testing and related fields. Standard C39/C39M for testing the compressive strength of concrete cyllinders was updated, as was C42/42m for obtaining and testing drilled cores and sawed beams of concrete.  The month of March also saw several geosynthetic standards being updated or added, including new standards for selecting the test method for geomembrane seams, and for testing the flexural rigidity of geogrids and other geosynthetics.  There are also a few updated standards related to asphalt mix design and sampling of asphalt.  Click through for updated ASTM Standards relating to geoprofessionals.

Last Updated on Monday, 16 April 2012 13:04
 
ASTM Updates for February, 2012 PDF Print E-mail
Written by Randy Post   
Sunday, 18 March 2012 23:38

American Society of Testing Materials Logo - ASTMThis post highlights recent changes to ASTM Standards affecting geotechnical engineers, materials testing engineers, soil and construction laboratory managers and related professionals.  Updates for February include: a new standard for geospatial data at coal mines; standards related to pervious concrete; an updated standard for volumetric concrete batching; and an update to D5778 - Standard Test Method for Electronic Friction Cone and Piezocone Penetration Testing of Soils; among others. Click through for the list.

 
ASTM Updates for January, 2012 PDF Print E-mail
Written by Randy Post   
Monday, 13 February 2012 23:50

American Society of Testing Materials Logo - ASTMNew and revised ASTM standards in the geotechnical engineering, construction materials testing and related industries for January, 2012. Click through for the list.

 
ASTM Updates December 2011 PDF Print E-mail
Written by Randy Post   
Wednesday, 11 January 2012 10:39

American Society of Testing Materials Logo - ASTMHappy New Year! Here are a list of updated and new ASTM standards related to geotechnical engineering, materials testing and other subjects of interest to geoprofessionals.  In this batch is a new standard for testing individual geogrid junction strength and other updated standards for geogrid testing.  The standard for geofoam has been updated, so has the standard for SPT sampling.  Read on for a list of these updated standards and others.

Last Updated on Friday, 13 January 2012 00:52
 
First National Green Building Code Approved! PDF Print E-mail
Written by Randy Post   
Thursday, 17 November 2011 15:42
Green building

LEED Certification is a voluntary process for building owners and designers. But a newly approved green building code developed by the International Code Council titled the 'International Green Construction Code' or IgCC may see adoption by many state and local governments. The code is officially published in March of 2012 and for jurisdictions that adopt it, will apply to new and renovated commercial and residential buildings over three stories tall. [Source: via ASCE SmartBrief. Image: IQS]

 
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