Seismic Shift

Seismic Shift

Architecturally pleasing and structurally sound, a California high school is now ready for quakes

By Paul Tarricone

Behind that pretty façade at Alameda High School in California is a sturdy structure, the result of a modernization and seismic retrofit that features a stylish yet rugged lighting design by O’Mahony & Myer (OMM), San Rafael, CA.

Listed on the National Register of Historic Places, the iconic multi-story neoclassical group of buildings dates back to 1924 and fills an entire block of Central Avenue, adjoining the city’s historic central business district. In the 1970s, the buildings were deemed unsafe as they did not meet current seismic standards, forcing the high school to move into a safer building.

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The road to recovery began with state funding and a bond measure in 2014. The modernization/seismic retrofit resulted in 37 state-of-the-art classrooms, 11 new science labs, designated outdoor learning spaces, and updating of the structural, mechanical and electrical systems—all with minimal visual impact. The exterior columns and terrazzo entry stairs, 350 wood windows, and the main lobbies were meticulously restored and brought back to their original grandeur. The two-year construction effort was completed in August 2019 at a cost of over $57 million.

OMM was brought on board by Quattrocchi Kwok Architects (QKA) in 2014 to provide an electrical and lighting system assessment of the 100,000-sq ft high school. “We discovered that the existing lighting system utilized fluorescent technology and luminaire selections which, while being very efficient technology at the time, did not enhance the beauty of the original neo-classical architectural design,” says OMM designer David Orgish. “Additionally, since the existing lighting system did not meet the current Department of the State Architect’s strict seismic structural requirements for lighting systems in public schools and lacked adequate emergency egress lighting, new lighting was included in the project.”

OMM’s scope of service included classroom, office and corridor lighting, as well as exterior illumination—all within the framework of the state’s seismic requirements. The incumbent lighting system, as Orgish explains, could have posed a risk during an earthquake: “In public school projects under the jurisdiction of DSA, pendants must be able to swing 45 deg without contacting any obstructions in a seismic event. Most of the existing pendant-mounted luminaires on the project utilized solid stems rather than aircraft cable suspension systems. Although the stems did have swivel adapters at the canopies, they did not swivel at the luminaire, so if the seismic forces caused the luminaire to sway perpendicular to its axis, it could, but if seismic forces caused the luminaire to sway parallel to its axis, it could not, which created a potentially unsafe condition for the occupants.”

The new lighting design, by contrast, incorporated linear luminaires which were aircraft cable-mounted to allow them to swing in a seismic event. “If they were going to hit an obstruction while swinging, like in the typical classrooms where we hung them coplanar with the acoustic panels, we laterally braced them so they could not hit the adjacent obstruction.” (Figure 1: the diagonal lines at each end of the pendants indicate cables up to the structure).

Classrooms, not surprisingly, were the predominant room type on the project. “Since many of the classrooms had existing piping at the ceiling plane,” says Orgish, “the architect decided to create a system of acoustic clouds to conceal the piping while providing additional sound attenuation.” In an effort to integrate the lighting approach with the acoustic approach, the linear LED direct luminaires (Finelite) were placed in between and coplanar with the clouds. “Additionally, in order to support more specialized learning approaches, we provided a linear Finelite LED wallwasher along the teaching wall.”

Orgish adds that the seismic requirements influenced the decision to specify the Finelite luminaires. “We chose them for the typical classroom luminaire because they have a secondary seismic safety mechanism which, if for some reason the cable gripper at the luminaire fails during a seismic event, there is a secondary ‘catch’ mechanism which will keep the luminaire from falling to the ground.”

Office spaces were illuminated with the same luminaire used in the classrooms, but “since the ceilings were finished and not open to structure, we changed the distribution to direct/indirect to provide appropriate illumination for these spaces,” says Orgish. “The existing windows, however, were higher than the lowered ceilings, so in order to prevent shadows at the windows we provided a wall-mounted indirect luminaire along the windows.”

Meanwhile, the hallways became the ideal canvas for referencing the neo-classical architecture. “Ceiling heights varied throughout the buildings depending upon which floor we were working on, so we used ceiling-or pendant-mounted decorative LED luminaires (Visa and SPI Lighting) with a neo-classic style to illuminate the public corridors.”

The seismic requirements influenced mounting location, especially in the hallways. “We used luminaires which would not look good with lateral bracing wires, so we customized the pendant lengths and paid particular attention to adjacent obstructions in order to meet the 45-deg sway requirement,” Orgish explains.

The exterior lighting scope was very simple, says Orgish. LED luminaires were required, but the luminaire style could not clash with the architecture of the buildings. General illumination of the hardscape along Central Ave was not needed, as the street was illuminated by existing arm-mounted, teardrop-shaped area lights. The project scope included new egress walks that connected the exterior doors to the existing public right of way. To illuminate these areas, OMM used customized light columns (Bega) with custom mounting heights, anchor plates and light distributions, including custom backside shielding to avoid scallops on the existing building façade.

Full façade lighting along Central Ave was considered but ultimately eliminated from the scope due to budget constraints. However, the historic nature called for lighting of both the Central and Science Building entries. Decorative pendant luminaires that would reference the neo-classical style of the building replaced the existing bulkhead luminaires at the exterior entry soffits. “Finding a manufacturer to provide a decorative luminaire with the scale required for the building in LED was particularly challenging since most exterior area light manufacturers now provide classically styled luminaires with LED arrays mounted in the tops of their lanterns in order to mitigate light pollution. Due to the close proximity of these luminaires to the façade, this approach created strong and undesirable scallops on the building. This prompted us to seek out a manufacturer that still produced area lights with center-mounted light sources and translucent lantern tops, which would give us a luminaire with a glowing general light distribution at the entries.”

OMM eventually specified a post-top luminaire (Neri) customized into a chain-hung pendant with translucent windows to provide the general light distribution required. For seismic safety, the decorative chains on the pendants keep the luminaires from swinging laterally. “Although this approach gave us the decorative look at the entries, it did not illuminate the façade adequately so we added a series of asymmetric linear LED wall washers (Lumenpulse) to illuminate the space between the entry columns at the Science Building and in between and behind the entry columns at the Central Building.”

More than 40 years since the school doors closed, seismic safety has returned—with some sizzle.

Contributor(s)

Paul Tarricone

Paul Tarricone