What LA's New Seismic Retrofit Law Means for Building Owners
Recognizing LA’s high risk for earthquakes, the LA City Council last month enacted the strictest seismic regulations in the nation. The new law requires an estimated 13,000 “soft-story” wood-framed buildings be seismically strengthened. These are typically multi-story apartment buildings with soft, weak or open front wall lines. The ordinance also includes about 1,500 “non-ductile concrete” buildings considered vulnerable to earthquake damage and potential collapse.
Seismic building retrofits are estimated to cost $30k to $250k for wood structures, but could be millions for large concrete apartment towers. Third-party lending options that link construction loan repayment to property tax payments can provide some relief for owners, the most notable of which is the AllianceNRG PACE program. Currently, landlords can push rents up $75/month to cover repairs for substantial renovations, but the City Council has proposed splitting costs between owners and renters, but limiting rent hikes to $38/month in areas with rent stabilization rules.
To get a better idea of what this means for building owners, Bisnow caught up with locally based Partner Engineering and Science Inc's technical director of structural engineering, Jay Kumar, who tells us that the first thing building owners should understand is that the law's retrofit requirements has two objectives: protecting human life and safety and preventing buildings from becoming uninhabitable after a major earthquake.
The ordinance addresses very specific building deficiencies and is not intended as a global damage protection approach. "The ordinance is geared to keeping buildings from collapsing, but owners can pursue upgrades for a higher performance objective," he says, noting that structural engineers can assist with such a design.
Soft-story wood-framed buildings have large openings on the first level, where parking is tucked underneath. "A slender column system is used to support sections of the building, but it provides very little lateral stability, so sustained ground shaking can cause the building to collapse on the columns," Jay explains. Current code discourages building designs with this structural deficiency.
Under the new law, soft story buildings or those with soft, weak or open-front wall lines, must comply with the new requirements. The city is in the process of notifying building owners affected by the new law. Courtesy notices are expected to be sent to building owners in early 2016 and formal orders to comply are expected to be released over the next year or two, Jay notes.
After the order notice is received owners have one year to submit structural calculations and plans to demonstrate their building does not require retrofit and or complete designs and obtain permits for the upgrades within two years. Work must be completed within four or seven years or the building will be demolished.
Jay says there are a variety of tools and options available to stabilize these structures, the most common of which is is adding new steel moment frames in the parking areas that attach to existing framing. The new moment frames are fixed to the foundation hidden below the ground.
"This has to be done in a way to provide stability when the ground moves, but the system must be designed to not over-strengthen the ground floor. If the new supports are too stiff, they can force the collapse into the second story," he adds. "Adding steel moment frames is the preferred fix because it can be implemented without losing parking or requiring tenants to move while construction is underway."
Non-ductile concrete buildings (like the one pictured, which collapsed in the Northridge Earthquake) do not contain an adequate amount of internal steel reinforcing. New concrete buildings are designed to prevent brittle failures during strong ground shaking. In these newer buildings even if the concrete breaks, the buildings won't collapse, but "it is designed to hangs on to the bitter end," Jay says. Non-ductile concrete buildings, however, may not remain stable if damaged. He notes that the common retrofit strategy for these buildings is to add new reinforced concrete shear walls.
The cost to improve these buildings depends on the size of the structure and scope of work, Jay notes. The new law requires building owners to file a report within three years, but they have 25 years to complete upgrades or prove that no upgrades are necessary, he says.
When considering acquisition of older apartment buildings, Jay suggests a seismic inspection prior to closing. He notes most sophisticated banks, insurance companies and other institutional investors have policies that require seismic inspection before financing a deal or adding an asset to their portfolios.