March/April 2021 - 62

colleagues at Oregon State University have been examining
the seismic performance of rigid inclusions (DFI Project No:
CPT-2018-GRIM-1). These projects have already provided vital
information to designers, consultants, contractors and owners
for the continued expansion of the use of rigid inclusions.
Gallant and his team have focused on two design aspects.
One is the common practice of embedding horizontal layers of
geosynthetic within a granular platform to facilitate the
transfer of load into the underlying rigid inclusions. Based on
field measurements and observations for an Iowa project,
they have concluded that the efficacy of the geosynthetic is
limited where a firm upper soil is present. The second focus
has been the ability of rigid inclusions to transfer axial load
after a fracture develops due to bending. Their study supports
that, though rigid inclusions crack and lose bending capacity,
no cessation of the vertical load transfer occurs. The latter
finding is very significant as it will help a designer to
determine whether steel reinforcement addition is necessary.
Stuedlein's team performed numerical simulations to

quantify the redistribution of cyclic stresses resulting from
the presence of rigid inclusions with properties of timber
piles. Recognized as a baseline for more advanced future
models, the current research used a 3D dynamic, linearelastic, finite element model created in OpenSees. Based on 64
different scenarios, the reduction in the cyclic stress ratio was
observed to be most sensitive to rigid inclusion spacing,
moderately sensitive to length, and least sensitive to the soil
relative density. Future plans include expanding the research
to incorporate nonlinear soil behavior, liquefaction and other
design components (e.g., a load transfer platform).
We are fortunate to have Gallant and Stuedlein involved in
DFI projects. Please contact them directly to learn more about
their work (aaron.gallant@maine.edu, and armin.stuedlein
@oregonstate.edu ), or see Gallant's 2020 article in the Journal of
Geotechnical and Geoenvironmental Engineering (145[6]), and
Stuedlein's 2021 one in Soil Dynamics and Earthquake Engineering
(www.sciencedirect.com/science/article/pii/S0267726121
000361).

WORKING GROUP CO-CHAIRS PAUL GILDEA, P.E., AND TERRY HOLMAN, PH.D., P.E.

Working Platforms
The Working Platforms Industry-Wide Working Group found
success during the fourth quarter of 2020 in developing a
comprehensive program to improve working platform
conditions for foundation construction equipment. These
efforts were the most recent in a focused initiative begun in
2017 as a collaboration between Deep Foundations Institute
(DFI), The International Association of Foundation Drilling
(ADSC) and the Pile Driving Contractors Association (PDCA).
Over 100 members of the three organizations participated in
2020 activities to move the campaign forward, culminating in
publication of Recommended Industry Practices for Safe Working
Platforms for Construction Equipment on December 15, 2020
(www.dfi.org/viewpub.asp?tid=TM-WPSAFETY).
This document follows the group's development of a
position statement in 2018 detailing the problem and the
organizations' positions regarding the importance of proper
procedures for planning, preparing, and designing appropriate
working platforms for construction equipment.
The new document seeks to provide recommendations for
in-house administrative programs and project communication
to institutionalize standard evaluation and design procedures
for working platforms on construction projects.
Recommendations do not include technical specifics on rig
loading analysis, bearing capacity evaluation and working
platform design. Instead, the Guide to Working Platforms,
published by DFI and the European Federation of Foundation
Contractors (EFFC) in December 2019, addresses technical
considerations and is the most current publication on working
62 * DEEP FOUNDATIONS * MAR/APR 2021

platform design and
analysis methodology
for working platforms
(www.dfi.org/viewp
ub.asp?tid=TMPaul Gildea
Terence Holman
PLATFORMS).
The working group will be communicating with key
groups in the construction industry to transmit the concepts
contained in the administrative practices document, and to
bring about a more universal understanding of the hazards
unsuitable working platforms present and the need for
established practices to evaluate site conditions and
equipment used to construct suitable working platforms.
Communication is also needed to standardize understanding
of the contractual roles and responsibilities of various parties
involved in the work. Targeted groups include general
contractors, owners, and insurance industry representatives.
The working group is also geared up to educate foundation
industry members about appropriate policies and procedures
for safe working platforms. A half-day course is planned
during the International Foundations Congress and
Equipment Expo (IFCEE) in Dallas, Texas, on May 11, 2021
(available for online participation at www.ifceexpo.com).
This first course will instruct professionals on the basics of
administrative procedures and assignment of responsibility
for working platforms for foundation construction equipment. Limited technical information will be covered on
evaluation of equipment loading and basic platform design.

http://www.sciencedirect.com/science/article/pii/S0267726121000361 http://www.sciencedirect.com/science/article/pii/S0267726121000361 http://www.dfi.org/viewpub.asp?tid=TM-PLATFORMS http://www.dfi.org/viewpub.asp?tid=TM-PLATFORMS http://www.dfi.org/viewpub.asp?tid=TM-PLATFORMS http://www.dfi.org/viewpub.asp?tid=TM-WPSAFETY http://www.ifceexpo.com

March/April 2021

Table of Contents for the Digital Edition of March/April 2021