Structural Engineers Association of Northern California Newsletter - March 1996

Pier 39 Aquarium Featured at February Dinner Program

By Martin Bollo, Program Committee

The February 6th SEAONC dinner program featured a presentation on the new aquarium at Pier 39 named "Underwater World". Three speakers discussed different aspects of the design and construction of this 48,000 square foot, three-story project, which is due to open to the public in April.

Tom Wilson of the construction management firm of Lehrer, McGovern Bovis discussed the overall planning issues and complex construction sequencing of this project. The permitting process involved over seven years of litigation, as well as up to twenty meetings with the Bay Conservation and Development Commission (BCDC) and the Port of San Francisco. Construction started on June 1, 1994 and the total construction cost is estimated at $48.1 Million. The aquarium is being constructed to the east of the existing Pier 39 shops on concrete piles with two stories of cast-in-place and precast concrete, and a third steel-framed level. The aquarium will feature a moving walkway transporting visitors through an acrylic tunnel under a 707,000 gallon seawater tank housing indigenous aquatic species and refreshed with treated water pumped from the San Francisco Bay- Special design considerations include a minimum 3 inches of concrete cover over reinforcing steel to avoid detection of the electromagnetic signal by the sharks that will be housed in the aquarium. Construction is currently ahead of schedule and under budget.

Goerge Fotinos of Ben C. Gerwick Inc. discussed the complex foundation and base slab design. The structure is isolated from Pier 39 and is supported on 48 inch diameter, 120 foot long cylinder piles beneath the main aquarium tank area and 24 inch octagonal piles elsewhere. The bottom deck is actually partially below high tide and so was constructed of precast panels that fit over the piles with a concrete topping slab. Seismic design considerations include use of a site-specific response spectrum and a push-over analysis. Epoxy-coated rebar was used along with a low water-cement ratio, high fly ash content concrete mix design. All concrete work was performed at night to avoid disruption to Pier 39 traffic.

John Harrison of David Evans associates described the design of the concrete and steel superstructure. Heavy wall reinforcement was used along with a 7000 psi concrete mix design that also contained pozzolans. The non-rectangular floor slab shapes required complex, multi-layered rebar layout patterns. A 12 inch seismic joint was provided at the pedestrian bridge connecting the aquarium and Pier 39.