All on the job agree: The most challenging and striking design feature of the $185-million central library replacement under construction in San Diego is its steel lattice dome. The shape, which will top the eighth-floor reading room of the nine-story library, is designed to be a symbol for the city as well as a working part of the building's shading system, says Rob Wellington Quigley, the local design architect for the project.
A modern interpretation of the classic shape, the dome is designed to function on both an emotional and practical level, says Quigley. “The dome is not glass, but open lattice,” he says.
The perforated-metal skin will let daylight into the main reading room, which has a 60-ft-high ceiling. And also like a trellis, the lattice provides critical shading from the sun, he adds. That in turn reduces the air- conditioning load without blocking views of the city.
“It also helps protect the ninth-floor outdoor terraces from our afternoon breezes and makes them more usable,” says Quigley, founder of the firm that bears his name.
Quigley sees the 498,000-sq-ft library as essential infrastructure, like city streets. Designed in collaboration with Tucker Sadler Architects and structural consultant Martin Libby Engineers, both of San Diego, the building is intended as the crown jewel of the city's 35-branch library system. It is twice the size of the current central library and more elaborate, says the architect.
The building will contain a 400-seat multipurpose chamber and a 350-seat auditorium. There will also be a 9,141-sq-ft children's library, a 3,797-sq-ft teen center, a technology center, an art gallery, 400 computer workstations, a coffee bar and an outdoor plaza and cafe.
Turner Construction's San Diego office, the construction manager-at-risk, broke ground on the project in July 2010. Completion is set for March 2013.
“Definitely, the greatest engineering [and construction] challenge is the structural steel dome,” says Carmen Vann, Turner's project executive. The amount of detail and effort going into coordinating the construction and installation of the dome is “astonishing,” she adds.
The frame consists of eight large “sails” that piece together to create the shape. The largest sail measures 100 ft from top to bottom and the smallest, 60 ft.
CUSTOM WINDOW WASHING
The dome will have a window-washing system custom-designed for the structure. The top of the reading room will contain mechanical equipment and house the window-washing boom, Vann says. A boom arm will be on top of the dome, which at its highest point will reach 205 ft above grade. The boom will pivot around the dome as it cleans.