November/December 2021 - 99

values of the load were plotted versus
strain for each strain gage level. From
the ETL and the load-strain plots, the
uniform loads transferred from the RSystem
to the upper and lower
foundation portion became evident.
Conclusion
In the top-loaded bidirectional test
(TLBT) described and tested, all loads
were applied by a reusable load assembly
located at the foundation head.
Additionally, the TLBT arrangement
allows the construction of a bored or
drilled foundation to follow standard
practice without requiring special
arrangements to bypass the obstruction
within the foundation element
created by a jack assembly. The TLBT's
R-System allows for a center-line
tremie to pass through the middle of the
foundation without construction
modifications. Furthermore, any
damage to the jack assembly can be
repaired at the surface, minimizing the
need for abandoning the test foundation.
As a result, the new test offers a
constructability and a reduced risk of
test component failure.
It is realized that like any new
Equivalent top-loading curve of TLBT results
development and technique, several
challenges and limitations must be
addressed. To address those limitations
and overcome those challenges, more
tests need to be completed. However, the
initial test results indicate that the TLBT
method could be highly beneficial to the
deep foundation industry. The TLBT is
also beneficial to project owners
because more tests can be completed
due to the test's financial advantages.
The testing method is also beneficial to
specialty contractors since the TLBT
system does not require them to change
the means and methods of drilled
foundation installations. Additionally, a
specialty contractor can procure and
fabricate the rebar cage so that the TLBT
system is already installed within the
cage. So, there is no additional assembly
arrangements required prior to testing.
Finally, this bidirectional load-testing
approach is extremely beneficial to the
foundation engineering community,
since the practical test setup allows for
unlimited jack stroke, thus allowing for
use of a higher resistance.
Rozbeh B. Moghaddam, P.E., Ph.D., is an adjunct
faculty member at The University of Texas at
Austin, and president of RBM Consulting Group.
He has been involved in the deep foundation
industry since 2002.
Strain-load relationship for three TLBT strain gage levels
DEEP FOUNDATIONS * NOV/DEC 2021 * 99

November/December 2021

Table of Contents for the Digital Edition of November/December 2021

Table of Contents
November/December 2021 - Intro
November/December 2021 - 1
November/December 2021 - 2
November/December 2021 - Table of Contents
November/December 2021 - 4
November/December 2021 - 5
November/December 2021 - 6
November/December 2021 - 7
November/December 2021 - 8
November/December 2021 - 9
November/December 2021 - 10
November/December 2021 - 11
November/December 2021 - 12
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November/December 2021 - 15
November/December 2021 - 16
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