Canyon Bridge Rehab - Second Truss Back on
River
Jeffersonville, August 3, 2004 - Preparations began about 7:30 in the morning. By
eleven o'clock, the second truss had been replaced over the Brewster River.
As done with the first truss, an I-beam with slings was
prepared to lift the truss by the bottom chords. While the truss is being raised to an upright
position, its structure can flex. Because the diagonal braces are held in place by the dead-load of
the structure when standing, if the loading is released the braces can move in their seats. To
correct this, the truss is raised to an upright position, set on blocks and held there while the braces
are driven back into place.
The truss is returned to the abutments and braced to
its mate with temporary tie-beams. Next, the floor and roof systems will be put back, followed by
new roofing and siding.
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Preparing the truss for lifting. Photo by Joe Nelson,
August 3, 2004
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The two "end" floor beams are located where the Burr arch meets the chord, so
the arch planks here are ported to receive them; the ports on the second truss need to be threaded
onto these two floor beams. Photo by Joe Nelson, August 3,
2004
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Going up. Notice the flex in the truss. Photo by
Joe Nelson, August 3,
2004
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The truss is set upright on blocks and braced to stand.
Photo by Joe Nelson, August 3, 2004
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Roland Blais drifts the braces into their seats with a
mallet called a beadle (pronounced "biddle"). Photo by Joe Nelson, August 3,
2004
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The truss is airborne. Note the new members. Most of the original fabric of the
truss is preserved.
Photo by Joe Nelson, August 3, 2004
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The upstream truss is back where the builders had put
it some hundred years ago. The first temporary tie beam is in place. Photo by Joe Nelson,
August 3,
2004
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