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Recent Sacramento Glulam Failure

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>From Today's Sacramento Bee:

County agency to seek roof beam inspections: Skate rink accident spurs study
proposal
By Kevin Yamamura
Bee Staff Writer
(Published July 27, 1999)

Citing beam failures similar to one that caused a Foothill Farms skating
rink roof to collapse last month, the Department of County Engineering will
recommend today a task force examination of "glu-lam" wooden spans used in
older buildings.
The failure of a glu-lam beam, the generic term for a large span consisting
of laminated wooden boards glued together, was responsible for a roof
collapse that injured two people June 18 at the Foothill Skate Inn, a
26-year-old building at 4700 Auburn Road.

Sacramento County officials identified at least six similar area incidents
since 1985, as well as recent ones in Santa Rosa and Chico. While Chief
Building Inspector Don Schultze insisted that glu-lam beams are safe, he
said these cases indicate a need to inspect buildings with wooden spans.

"Glu-lam beams have performed very well, but they are enough of a concern
that we just don't want to ignore them without serious study," he explained.

In a report released June 25, Carl Schubert, a structural engineer hired by
owners of the Foothill Skate Inn, determined five factors contributed to the
75-foot beam's collapse -- the beam's weakening to mechanical vibration,
shrinkage caused by wood drying, temperature, bolt location and heavy
rainfall loads.

Both Schubert and Schultze, however, pointed to bolt location as the main
cause of the beam's failure. Glu-lam beams typically expand and contract
over time due to humidity, and building codes suggest that beams only be
bolted on one end to allow for such movement. The skating rink's beam was
bolted on both ends, however, and had shrunk enough to weaken and break,
they said.

While most engineers now use proper bolt location when designing buildings,
such practice was less standard when the Foothill Skate Inn -- which met all
code requirements -- was built in 1973.

For that reason, Schultze is particularly concerned with buildings more than
20 years old that have glu-lam beams. Because bolt location was not solely
responsible for the beam failures, the proposed task force would examine a
number of other factors, such as age, that can cause glu-lam structures to
deteriorate.

Glu-lam beams typically are used in one-story buildings, such as warehouses
or recreational facilities. Cheaper than steel and comparable in strength,
they are especially popular in California because of its proximity to the
Pacific Northwest timber industry.

"As long as glu-lams are maintained properly, they can last indefinitely,"
said Bruce Pooley, spokesman for the Englewood, Colo.-based American
Institute of Timber Construction, a glu-lam trade association. "The first
American glu-lam structure built 65 years ago is still standing."

Schultze said he does not question the construction of glu-lams as much as
how they are installed and treated. The goal of the task force, which he
will recommend during today's Board of Supervisors meeting, is to find ways
to prevent accidents, possibly through a mandated inspection of buildings
similar to those that have suffered glu-lam failures.

FYI

Fred Turner, Staff Structural Engineer, California Seismic Safety
Commission, 1755 Creekside Oaks Drive Suite 100, Sacramento, CA 95833
916-263-0582 Work Phone, 916-263-0594 Fax fturner(--nospam--at)quiknet.com