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TRU-FRAME
Steel Truss
The Need
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After earthquakes, repair and
replacement of structural elements is time consuming and expensive. This new truss system
contains several diagonal elements designed to absorb seismic energy and yield at
prescribed levels. After a quake, the diagonals are easily accessible for repair or
replacement.
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The Technology
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Fabrication of the horizontal framing takes days
with this system, compared to weeks in a conventional wide flange system. Erection time
saving can vary based on quantity and size of frames along with inspection requirements
but the minimum time savings achieved should be 20% with potential reduction of as much as
70%. Standard moment frame design requires 100% visual inspection and ultrasonic testing
which is eliminated when using the Tru-Frame system. Since all Tru-Frame connections are
single pass fillet welds and tension control bolts, they can be visually inspected any
time after completion without need for additional testing. This allows subsequent trades
to start their work sooner. On a standard 100,000 square foot commercial office building
there would be at least a two-week reduction in the erection schedule alone. |
The Benefits
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- Tru-Frame provides both substantial cost and time savings
while providing a better level of performance. It provides cost savings in material and
shop fabrication and in erection.
- An open web steel joist typically weighs about 20% less than a
wide-flange beam capable of carrying the same gravity loads.
- Fabrication costs for open web framing are about 20% less than
fabrication cost of comparable wide-flange beams.
- The combination of less weight per square foot of building
area and less production cost per pound provides a 30% savings overall on the material.
- Shop drawing time is dramatically reduced since the drawings
are prepared in conjunction with the development of the contract documents.
- Fabrication time is cut in half for open web framing versus
conventional wide-flange frames due to the split responsibility between the steel
fabricator just providing the columns and the joist manufacturer fabricating all the
horizontal framing.
- Labor costs are reduced by as much as 90% due to the reduction
in connection testing time.
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Status
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In 1997, steel producer, Nucor Corp. released a
draft guide for designing "special moment-resisting truss frames" - aimed at
reducing earthquake damage to steel structures and put it into use by developing a
practical in-field application from the study findings, the Tru-Frame. On Gateway Oaks Iv, an 84,000 square foot four-story office building,
savings of almost $3.00 per square foot in the steel structure were achieved and the
project schedule was accelerated two months, allowing early occupancy and an additional
savings to the owner of another $2.00 per square foot.
Construction
Innovation Forum honored Tru-Frame as one of the winners of 1999 Nova Award. |
Points of Contact
- David Downey. Earl Construction Co. 3940 Industrial Blvd. #
100 D, West Sacramento, CA 95691. Phone: (916) 371-4100
References
- 1999 Nova Award Nomination Entry, "TRU-FRAME steel truss
moment framing".
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. |
AK, SL
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