The phrase "an ounce of prevention is worth a pound of cure" is applicable even when it comes to seismic retrofitting for your building. Whether you’re looking to increase structural safety, minimize business interruption, or simply save on insurance costs, choosing the right structural engineer will help you come up with a cost-effective, tailored retrofit plan that’s right for your property.
To the Code – and Beyond
Provided that your building isn’t undergoing major alterations or a change of occupancy, and the retrofits are voluntary, the minimum scope of seismic work isn’t necessarily set by building code. You can do as much or as little as you like – as long as you don’t make the building any worse, explains David Bonowitz, chair of the National Council of Structural Engineers Associations’ Existing Buildings Committee.
While you want to make sure your building does meet code, you also want to make sure the retrofits make sense for your business. A good structural engineer won’t talk about the cheapest options, but the most cost-effective, says Peter Yanev, a structural engineering consultant based in Northern California. "What do you do beyond the code to give a cost-beneficial solution that will pay for itself in the first earthquake, or in reduced insurance over the next several years?" The engineer should be willing and able to discuss your objectives in terms of safety, post-earthquake repair and recovery costs, and post-earthquake business interruption, and then develop a seismic retrofit plan for your building.
Yanev and his team retrofitted the Anheuser-Busch facility in Northridge, CA, shortly before the Northridge earthquake in 1994. The brewery estimated that the total loss, if not for the retrofit, would have been more than $750 million when calculating direct damage to property, loss due to business interruption, and potential loss of market share due to lost production time. The total cost of the retrofit was $10 million, says Yanev.
Not All Engineers are Created Equal
"Existing buildings don’t present the same blank canvas and often involve surprises or unknown conditions late in the game," Bonowitz says, "so they tend to require more customized, less pre-determined solutions." Because of this, look for an engineer who is able to apply judgment and discretion in the absence of a governing code.
When retaining structural engineers for upgrades, be certain that they’re experienced in doing upgrades as opposed to designing new buildings. "It’s a very different area of practice," says Ronald Hamburger, senior principal at Simpson Gumpertz & Heger Inc. "Every structural engineer is taught to know how to design in accordance with building code. Designing a seismic upgrade is a specialty practice, and not every structural engineer is going to be good at designing upgrades."
Look for an engineer with a willingness to explore alternative approaches – there are often a number of different ways a building can be upgraded. The best way to upgrade is a blend of the most economical way and what has the least impact on the building’s use during and after the work is done, Hamburger explains.
Mind Your Materials
"Most buildings that merit retrofit also present obsolete or archaic materials, systems, and details," says Bonowitz. "The existing structural elements might not be reliable in an engineering sense. Therefore, the right retrofit engineer is one who can recognize and work with these non-compliant conditions."
"You might want to select an engineer who has done upgrades of the same type of construction," says Hamburger. "The way you upgrade an unreinforced masonry or brick building is going to be very different from the way you upgrade a reinforced concrete building, and that will be different from the way you will upgrade a wood or steel building."
Yanev recommends looking at an engineer whose résumé includes retrofits in schools and hospitals because these buildings are subject to stricter codes. "If they’ve worked on schools and hospitals, they’ve been subjected to higher requirements and know what it takes to go to a higher level."
And like anything else – you’ll probably get what you pay for. "It’s always a bad idea to choose any professional based on price," says Hamburger. "You really want to consider the person’s track record and their demonstrated ability to do the work."
Kylie Wroblaski ([email protected]) is associate editor at Buildings.