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Lateral
STATNAMIC Testing
The Need
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Lateral loads, which are
analyzed using static soil response parameters, usually control the foundation design.
These are normally dynamic loads caused by earthquakes, ship impacts and wind. When
feasible, design parameters are checked with full scale static loading testing. The
traditional static testing is very costly, dangerous, time consuming, and limited to loads
that can be generated by a hydraulic jack. Dynamic load
testing methods do not provide direct measurements, induce high accelerations, and
load-displacement behavior is controlled by the action of stress waves. |
STATNAMIC device
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The Technology
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STATNAMIC testing overcomes the practical
difficulties of both static and dynamic load tests. Lateral STATNAMIC testing was developed to better model dynamic loading on
structures and foundations. The measured dynamic response provided by STATNAMIC can also
be used to calculate the derived static response. STATNAMIC system was developed by adapting an axial test device. The device
consists of three main parts: piston, cylinder/silencer, and reaction masses.
The piston contains a load cell for
measuring force and a laser sensor to measure displacement. Solid propellent is burned
inside the piston to generate a gas pressure. The piston is mounted horizontally on a
foundation using a hemispherical bearing to minimize any eccentricities in the load.
The cylinder/silencer which fits over the
piston is accelerated by the expanding gas to over 15g's. A sled holding the reaction
masses and cylinder/silencer separates from the piston and slides down a track.
The accelerated masses generate a force
equal to the mass times acceleration. A patented system of motion sensors placed
horizontally in inclinometer casing embedded in the foundation measures the lateral
acceleration of the foundation at various depths. Strain gages embedded in the foundation
measure the strain at those same depths. This allows the engineer to calculate soil
response which then can be used to create computer model of the soils and foundation. |
14MN Lateral over-water STATNAMIC test, Mississippi
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The Benefits
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- STATNAMIC applies loads up to 30 MN (3,400 tons).
- Foundations tested include high capacity drilled shafts,
steel piles, auger cast piles, timber piles, batter piles in clay, rock, silt, and sand.
- STATNAMIC can test bridge foundations, pile groups, spread
footings, and off-shore piles.
- STATNAMIC can test the lateral capacity of foundations.
- Production piles can be tested without prior planning. No
reaction piles are required.
- Three 600 ton tests can be conducted in a one day shift.
- Several STATNAMIC tests can be conducted for the cost of a
single static test.
- STATNAMIC loads the pile and soil together.
- The duration of loading is on the order of 10 Hz.
- STATNAMIC's built-in load cell and laser sensor provide
direct measurements of load-displacement behavior.
- STATNAMIC produces load-displacement results immediately on
site.
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Status
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This system was most recently
used on a bridge replacement project in Mississippi where a lateral loads of 7.32 MN (823
tons) was imparted on a bridge pier founded on two drilled shafts. The bridge was designed
to accommodate heavy automobile and truck traffic, relatively high wind loads and must
withstand possible ship impact from vessels using a very active channel passing underneath
the bridge. The site also has the potential for deep scour. Two large bridge projects and one large retaining wall project are
planned for the remainder of 1998 and early 1999. STATNAMIC has also been widely used all
over the world such as Australia, Egypt, Holland, Indonesia, Japan, Malaysia, Taiwan,
U.E.A., U.K., and U.S.
This technology was honored as one of 1999
Nova Award Finalists by Construction Industry Forum. |
Points of Contact
- Michael Justason, P.Eng., Berminghammer Foundation
Equipment, Wellington Street Marine Terminal, Hamilton, Ontario, Canada L8L 4Z9, Phone:
(905) 528-0425, Fax: 528-6187, Email: mjustason@berminghammer.com.
References
- 1999 Nova Award Nominations, The Nova Award,
Construction Innovation Forum, Inc., October 1998
Disclaimer Statement
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Neither the Construction
Industry Institute nor Purdue University in any way endorses this
technology or represents
that the information presented can be relied upon without further investigation. |
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