One important consideration when
devising a construction project in the Bay Area is the ability of the structure
to withstand destructive seismic forces. If a structure is seismically unsound,
there can be disastrous consequences. When the Loma Pietra earthquake of 1989
rocked San Francisco and Oakland, many structures failed, including homes in
the Marina district that were knocked off their foundations, sections of the
I-880 freeway that collapsed, and the upper deck of the San Francisco-Oakland
Bay Bridge that crashed onto its lower deck on the eastern span of the bridge.
As the area looked to rebuild, professionals in the construction field, from
engineers to Bay Area commercial concrete contractors, came together to ensure the repairs and new construction
met high seismic safety standards.
After the earthquake and the collapse
of one of its sections, concerns were raised about the Bay Bridge and whether
it was seismically sound. Area experts and officials determined that a replacement of the Bay Bridge eastern span of the was necessary and so undertook what would become one
of the largest and most expensive public works projects in the state’s history.
The replacement involved constructing a new self-anchored suspension bridge and
two viaducts connecting Yerba Buena Island and Oakland and spanning San
Francisco Bay. Completed in 2014, the eastern span of the Bay Bridge is
composed of ten highway lanes, and at a width of 258.33 ft, it is the world’s
widest bridge. The new structure is expected to last 150 years with proper
maintenance and is engineered to withstand the largest earthquake expected in a
1,500 year period.
One final challenge
As with other large-scale and complex
construction projects, the eastern span replacement bridge was also met with
unforeseen challenges. In the final year of its construction, officials
reported that 32 rods, meant to anchor the bridge deck to the concrete
crossbeams, had failed and needed repair. Due to the way the rods were
installed, simple replacement was not possible, and instead a series of steel
saddles and post-tensioned jacket walls were used to secure the bridge deck. The Conco Companies was tasked with this complicated, custom repair and was able to
execute the final stages of the replacement bridge in order to safely open the
new eastern span of the San Francisco-Oakland Bay Bridge to eagerly awaiting
traffic.
Conco is a leading supplier of concrete services for the Western United States. As one of the leading commercial concrete contractors in the Bay Area, we have been involved with large-scale projects in the area including the new 49ers Stadium. Our concrete services include commercial, educational, parking and other construction development as well as public works projects and highways.
