Three companies that supplied or processed steel anchor rods
for a new replacement span on the earthquake-damaged San
Francisco-Oakland Bay Bridge have been cleared of
responsibility for a structural failure.
A spokesman for San
Franciscos Metropolitan Transportation Commission (MTC)
said a report by Californias Toll Bridge Program
Oversight Committee determined that none of the three
suppliersPainesville, Ohio-based Dyson Corp.,
manufacturer of the rods, or bolts; Tampa, Fla.-based Gerdau
Long Steel North America, which produced the steel; and
Glasgow, Mo.-based galvanizer Monnig Industries Inc.was
to blame for the rod failures.
"The report found that
none of those firms are responsible for the hydrogen
embrittlement," that caused the failure, the spokesman
The study determined
that responsibility is shared by the California Department of
Transportation, two design companies and the contractor on the
self-anchored suspension segment of the new span, a joint
venture between Coraopolis, Pa.-based American Bridge Co. and
Long Beach, Calif.-based Fluor Enterprises Inc., which the
spokesman said will share the estimated $20 million cost of a
permanent retrofit for the steel saddle and cable system.
In March, 32 of 96
galvanized ASTM A354 grade BD rods, or bolts, manufactured in
2008 broke when they were tightened to connect shear keys, or
seismic safety devices, on the new span (
amm.com, April 1).
Nearly 24 years after
its predecessor was damaged in the October 1989 Loma Prieta
earthquake, the new eastern span of the Bay Bridge opened to
traffic Sept. 2. The self-anchored span, initially estimated to
cost $1.4 billion and take four years to build, instead cost
$6.4 billion and took 11 years.
Most of the steel
suppliers had already denied culpability. Dyson claimed in May
that an earlier analysis for the state that determined that the
rods complied with the basic mechanical and chemical
requirements of ASTM A354 grade BD exonerated the fabricator of
fastener systems (
amm.com, May 17). Gerdau said the steel "met the
specifications" to which it was ordered (
amm.com, May 22). Monnig, which galvanized the
rods, declined comment.
Meanwhile, a second
batch of A354 grade BD 96 rod produced in 2010 arent
susceptible to hydrogen embrittlement similar to the rods
produced in 2008, the MTC spokesman said. The suppliers of the
2010 rod were the same as the 2008 rod with the exception of
Monroe, Mich.-based Gerdau Special Steel North America, an
affiliate of Gerdau Long Steel, which produced the steel.
"Clearly there are
some very large metallurgical differences between the 2008 and
2010 rods," said the MTC spokesman, who noted that testing has
been ongoing on the 2010 material, with "everything passing
without a problem."
XKT Engineering Inc. and Birmingham, Ala.-based Steward
Engineering Inc. are performing the permanent retrofit, the MTC