Inspec t i on and As ses sment
The Fremont Bridge is a three-span, tied-arch steel bridge crossing theWillamette River in Portland, Oregon. During construction of the bridge in 1973,
a severe brittle fracture occurred in one of the box-shaped tie girders at the junction with an arch rib. Subsequent inspections revealed small cracks and
other discontinuities in a number of the welds on the bridge. Five years after construction, the Oregon Department of Transportation retainedWJE to
develop a comprehensive retrofit plan based on inspection and testing of the tie girders.
The work on the Fremont Bridge represents one of the most comprehensive bridge investigations ever conducted by WJE, and established the
firm’s reputation as a leader in bridge fatigue and fracture assessment. In 1996, WJE returned to the Fremont Bridge to participate in the structure’s
ongoing maintenance program and to focus on fatigue and fracture cracks in the three-span main arch.
Notes of Interest
• Photographs taken by WJE engineers during the initial
work on the bridge in 1978 feature Mount St. Helens in the
distance, the top of which disappeared after the volcano
erupted in 1980.
• The main span of the bridge was built in California and
then assembled at Swan Island and floated in place on a
barge. On March 16, 1973, the 6,000 ton steel arch span
was lifted 170 feet using thirty-two hydraulic jacks. At the
time, it was listed in the Guinness Book of World Records
as the heaviest lift ever completed.
• It has the longest main span of any bridge in Oregon
and, until the future completion of the Caiyuanba Bridge in
China, is the longest tied-arch bridge in the world.
• The Fremont Bridge was the twenty-sixth peregrine
falcon nest site designated in Oregon after the raptor was
placed on the U.S. Threatened and Endangered Species
list in 1970.
First major investigation of fatigue and fracture of steel bridges. We developed a unique repair to
reduce the risk of failure. – John Hanson
The most comprehensive bridge investigation ever performed by WJE—this project establishedWJE
as a leader in bridge fatigue and fracture investigations. – Ian Chin
Many of the state-of-the-art retrofit concepts that WJE developed and successfully utilized to
upgrade fatigue sensitive details on the Fremont Bridge have become standards that are still widely
used today. – Bill Nugent
WJE 50 Years