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TRESTLE
Laborator y Tes t i ng, Ana l ys i s , F i e l d Tes t i ng
1979
In the late 1970s, the U.S. Department of Defense embarked upon a major research project to investigate the significant electromagnetic fields created
by thermonuclear blasts and their disruptive effect on military communication systems. A massive timber structure (TRESTLE) was designed to allow
a Boeing 747 aircraft, such as Air Force One, to taxi out and be supported within the middle of man-made magnetic fields. WJE was retained to perform
extensive laboratory testing of the glued-laminated beams, columns, wood bolts, and gusset plates. WJE also independently analyzed TRESTLE to verify
the adequacy of its design. Despite analysis results indicating that the structure had been properly designed, WJE was eventually hired to perform
full-scale load testing of the as-built structure.
TRESTLE remains the largest glued-laminated structure in the world. The project is also significant because of the diverse structural analysis
and testing services provided to assess this unique structure. The field load tests confirmed the structural adequacy of TRESTLE and verified the
accuracy of WJE’s earlier laboratory testing and computer analyses.
Notes of Interest
• TRESTLE, constructed at Kirtland Air Force Base, is
twelve stories high and 1,000 feet long, with more than
10,000 structural members equivalent to six million
board feet of lumber.
• The structure had to be entirely non-metallic so that it
would not disrupt the magnetic fields generated as part
of other Air Force studies at the site.
• After WJE had demonstrated by laboratory testing
and structural analyses that TRESTLE could safely support
a 747 aircraft, the Air Force was still nervous about its
structural adequacy. Jack Janney, who had served as a
Navy pilot duringWorldWar II, volunteered to personally
taxi Air Force One onto the TRESTLE platform to show his
confidence inWJE’s findings and to prove that the structure
was safe. His offer was not accepted and, instead, a full
scale load test was performed using heavily loaded quarry
trucks and aircraft tugs.
WJE 50 Years