September/October 2023 - 113

transmitted energy produced peak particle
velocities (PPV) of 0-13 mm/sec
(0-0.5 in/sec). On average, the PPV were
on the order of 7 mm/sec (0.27 in/sec). It
was possible to advance the foundation
through loose material near the surface
without oscillation, thus the zero
readings. The 13 mm/sec (0.5 in/sec)
responses were generated when more
dense or harder horizons were being
penetrated. Historic data from other
projects shows that PPV are on the
order of 10-15 mm/sec (0.4-0.6 in/sec)
in denser materials and may elevate to
on the order of 30 mm/sec (1.2 in/sec)
when hard material is encountered.
When the harder materials are encountered,
typically, the oscillation is
reduced to a more moderate level
which reduces the PPV. This typically
has the effect of decreasing the
installation rate below the 1 ft (0.3 m)
per minute target rate. This phenomenon
is somewhat reflected when
considering the vibration estimation
equation.
V = cW / r; where v = peak particle velocity, mm/sec,
r = distance from pile to point of interest, meters,
½
c = Soil type and hammer parameter.
W = energy transferred per cycle, J/cycle, and
For the dynamic hammer used on
the project, c = 1.0 for very stiff, dense
granular media/ rock and fill with
exceptionally large obstructions; 0.75
for stiff cohesive soils, medium dense
granular media and compacted fill; and
0.5 for soft cohesive soils, loose granular
media, loose fill and organic soils. Often,
because of the potential variability of
layered soil systems, a c value on the
order of 0.7 is used to provide a
prediction of the soil response to the
installation dynamics. The c values
indicated are to be used with the
maximum energy produced by the
hammer.
Typical earth vibrations during construction
Independently, it is possible to
instal l the foundations without
creating the potential to damage
surrounding facilities. The dynamic
earth response generated by the
equipment was less than that of most
of the construction equipment, and
while it was in the realm of the percept
ion threshold, the induced
dynamics were below that which
would create residential and or commercial
structure distress or impact
subsurface facilities. In all, the project
demonstrated the ability of winged
steel foundations to provide a suitable
alternative to drilled shaft foundations
in a constrained work area.
Summary and Conclusions
As the application of FRP technology
expands, analyses and designs have
been developed that provide alternative
deep foundations to more timeconsuming
traditional alternatives.
This paper presents a proposed
methodology, validated with field tests,
to design box stiffened
FRP deep foundations,
as well as
discussing the implementation
of this
app roa ch i n two
projects that used
stiffened steel deep foundations.
N. Catherine Bazán-Arias, Ph.D., P.E., works
for DiGioia Gray, part of Gannett Fleming in
Monroeville, Pennsylvania. Bazán-Arias has
more than 20 years of experience in soilstructure
interaction analysis and design,
transmission line siting and design, and dams
and retaining structures. She is a registered
professional engineer in eight states.
Phillip Glogowski, P.E., is with DiGioia
Gray and has more than 55 years of experience
in soil and rock mechanics, geosynthetic
engineering, soil structure interaction, and
materials analysis with an emphasis on
materials and soil and rock behavior and
instrumentation. He is a registered professional
engineer in Pennsylvania.
Steven Zhou, Ph.D., P.E., with Terracon
Consultants in Cincinnati has more than 20
years of experience in underground structures
such as tunnels, foundations, subway
stations and retaining walls. He is fluent in
numerical analysis and is capable of
developing computer software for geostructural
design.
Michael Pope, owner and inventor, with
FASTepc based in Heidelberg, Pennsylvania,
has more than 20 years of experience in
piling development and project management.
He has been part of more than 1,000
piling installations throughout the U.S.
DEEP FOUNDATIONS * SEPT/OCT 2023 * 113
September/October 2023

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