A company tough enough to handle a football stadium of seismic proportions
January 2013 - Candlestick Park has a long love-hate relationship with San Francisco baseball and football fans. Despite hosting two World Series and numerous NFC championships, the rich history of this stadium cannot prevent the structure from crumbling.
Who could forget the infamous power outages of the Dec. 19, 2011 49ers game when the field went pitch black twice? Besides its outdated facilities, the Stick is also a victim of its geography. Positioned near the San Francisco Bay and a large hill, the stadium experiences intense winds, freezing temperatures and of course, the threat of seismic activity.
Plans for a new 49ers stadium 45 miles south in Santa Clara began in 2006 but have been complicated by the recession with work hiatuses and budget timelines. Finally, ground broke on the project in April 2012 with a pending deadline for the 2014 NFL season.
A steel story
Builders Turner/Devcon Joint Venture, Santa Clara, Calif. needed the right kind of steel provider for this accelerated project, and that was SME Steel. “We were selected because of capabilities, price and schedule,” says SME Steel CEO, Wayne Searle. “We’re big enough to handle a job that size; we manufacture 2,000 tons a week.”
SME Steel, West Jordan, Utah, fabricates and erects structural steel for a variety of buildings. The company offers steel construction services including design assist services, consultation, detailing, shop fabrication and field erection.
“There were approximately 22,000 tons of steel, and it was erected in just over four months with four cranes,” says Searle. “It was a design assist project, which means we basically did full service in about 11 months. We did detailing, the management, the purchasing, the fabrication, the erection, the miscellaneous metals and some ornamental metals.”
Communication was key to the success of this BIM project. “It stands for building information model,” says Searle. “The building is modeled in a computer. The individual pieces are then fabricated and the model is used to coordinate with other trades.” Effectively working as a team with each specialized worker helped this fast-paced project move along. “There were weekly meetings in order to keep the request for information processes down; that can slow up a project,” he says.
“Typically, a question is formally asked in writing to create a paper trail, which then is sent to the engineer, architect or the general contractor, who provides the answer. This process usually takes two, three weeks sometimes, just because of the time frame,” he explains. “For this project, we have increased the number of meetings each week to handle these questions and discussions in a timely manner in order to minimize the time that it normally takes to complete a project.”
Handling a seismic load
The construction of the stadium has been unusual since its inception, with its constrained budget and time schedule, but Searle says, “the one thing that was very unique about this project is it’s the first football stadium, to my knowledge, that used CoreBrace.” CoreBrace is SME Steel’s brand of buckling restrained braces. “It’s like a shock absorber to keep a building vertical during an earthquake.
“It doesn’t buckle when it compresses, it’s rather scientific,” explains Searle. “The seismic energy is absorbed in the brace rather than the structure.” CoreBrace is made of three parts: an inner steel core, a casing of concrete and an outer steel tube.
According to the company’s website, “The inner steel core carries the loads, and the function of the concrete and steel tube is to act as a restraining mechanism for the steel core to prevent buckling that would normally occur under large compressive loads.” Another important component to creating these buckling restrained braces is to ensure the inner core does not adhere to the concrete and is not confined in any way where it cannot yield.
During Game 3 of the 1989 World Series, the Loma Prieta earthquake hit the San Francisco area, throwing baseball fans from their seats and causing minor damage to the stadium. The speedy installation of buckling restrained braces was crucial to this new project. According to a San Jose Mercury News article, after the custom-made bars arrived onsite, four crews attached up to five beams to a crane at one time. It reads, “They install about 50 pieces a day, more than about 35 beams per day for the typical project.”
The future home of the 49ers will seat approximately 78,000 people for the 2014 season. Although the project was a roller coaster of planning accelerations and setbacks, Searle says, “We’re really proud to be a part of that Turner Devcon team.” MM