STRUCTURES

Century Center II
Location: San Mateo, California

By using a creative structural framing design for this 10 story, 177,000-SF steel office building, C+D saved its client construction costs without sacrificing seismic performance. The building uses a unique lateral framing concept consisting of four lateral-braced steel frames with 2ft-by 3-ft composite concrete columns. This system concentrates wind and seismic forces in the building core permitting open, column-free tenant spaces. During the 1989 Loma Prieta earthquake, the design successfully limited the movement of the building preventing damage to non-structural finishes.

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San Mateo Plaza
Location: San Mateo, California

For the design of the San Mateo Plaza, Rubloff Development Company wanted an architect/engineering team that was familiar with high rise commercial office buildings and the site. The architect, NBBJ, and C+D Engineers have designed other office buildings in this area. The site, about 20 miles south of San Francisco, is underlain by deep, soft, bay muds. Sites like this cause two unique problems, building settlement and strong "long period" earthquake shaking. One-hundred-feet-long piles are used to provide support for the building on firm rock located far below the mud. Eight full height ductile steel welded moment resisting frames are incorporated into the building's structural system to resist the earthquake forces. Foundations are strengthened by using concrete grade beams, and a post-tensioned concrete ground level structural slab ties the entire foundation system and ground level together. This system was tuned for optimum seismic performance by using a dynamic analysis with special site specific earthquake response spectra.

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150 South Fifth
Location: Minneapolis, Minnesota

For the design of this 35-story commercial office building, we used wind tunnel tests of static and aero-elastic scale models to establish structural core size based on acceptable occupant-perceived wind-induced accelerations, vibrations and drift.

The result? A jump-form cast-in-place concrete core.

The central core has three elevator cells at the base with 18-inch-thick perimeter walls and a 19-inch wall separating the cells. A cell is stopped at the 16th and 27th floors. Reduced building stiffness coincides with elevator banks that serve the lower, middle and top floors of this landmark building.

Special vibration studies of floor framing schemes were influential in the selection of a composite 45-foot-span floor framing system. We studied schemes including slab girder floors, steel joists and composite steel girders.

This $40-million project also included a 55-foot excavation for five levels of post-tensioned garage floors, steel framing for perimeter columns and floors, and the design of a "skyway" link to the adjacent 100 South Fifth office building.

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Liberty Ship 1
Location: Sausalito, California

This 17,000 sf commercial office and storage building used prefabricated steel building field bolted gable frame system along with exposed steel architecture. A grid mat foundation was used to distribute loads over this Sausalito Marina shoreline soft soil site. Location and design made this an attractive home for tenants from the opening day in 1991.

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Bridgeway Technology Park
Location: Newark, California

C+D was retained by OPUS Architects and Engineers to provide structural engineering and construction administration services for the Phase I, II, and III facilities at Bridgeway Technology Park. Together, the three buildings provide over 240,000 square feet of industrial and office space.

Bridgeway Technology Park is located approximately 3 and 14 miles from the active Hayward and San Andreas Faults, respectively. The design criteria included 1994 UBC provisions, in addition to state of the art connections and detailing to provide superior seismic performance. Each structure utilizes concrete tilt-up panel construction and panelized roof systems. The completed construction for all three structures was within budget and on schedule.

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Scott Creek Business Park
Location: Fremont, California

This project involved the construction of five a new tilt-up buildings totaling over 300,000 square feet in Fremont, California. The buildings structural systems are concrete tilt-up walls, steel interior columns, glue-lam roof girders, and wood-truss/2x4/plywood panelized-roof systems.

The preliminary structural system is similar to previous projects for OPUS. Foundation systems depended on the recommendations of the geotechnical engineer. Local sites have expansive clays, and these expansive characteristics influence foundation and subgrade behavior. This issue effected selection of the spread and continuous foundations and preparation for slabs-on-grade. Lime treatment and overexcavation of soils was utilized to reduce subgrade soil moisture change movements Structural systems: Foundation Continuous and spread concrete footings Walls Concrete tilt-up Roof Glu-lam girders, timber trussed-purlins, 2x4 rafters, plywood sheathing Floor Concrete slab-on-grade.

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101 Nellen Office Building
Location: Corte Madera, California

This Marin County office building consists of an irregular plan and 2 column free floors. Situated close to the San Francisco Bay in an area of unconsolidated bay mud, the site presented structural challenges including high settlement and amplified seismic ground motions.

Precast/prestressed concrete piles in excess of 100 feet long are used to support the structure and exterior plaza. The 2nd floor makes use of a composite structural framing system to keep both weight and floor deflections low. Ductile steel moment frames are used about the perimeter, a solution that provides very good seismic performance while maintaining the architectural purity of the window filled facades. The exterior walls are non-bearing light gage steel curtainwalls with EIFS. The entry features are also constructed of light gage steel.

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Richmond / Bayview
Location: Richmond, California

The developer and architect wanted a simple low cost structure system, that could be expressed in the exterior and interior architecture, on a site that created interesting triangular shaped buildings with two story glass lobbies. C+D selected reinforced concrete masonry units and a timber truss roof system to enclose the buildings for only $55 / square foot shell construction cost. These buildings have been continuously occupied by tenants since constructed in 1994.

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Schoonmaker Addition
Location: Sausalito, California

This new 14,000 square foot office building was constructed as an addition to three buildings that served as the Bechtel Ship Yards during WWII. C+D engineers worked closely with Architect Charles Stewart to develop an exposed steel framing system, which transcends the industrial past and mixed-use future of the site. The 60,000 square feet of original timber framed buildings were remodeled and given new facades, and the entire complex was repaved and landscaped to create an entirely new look for the old shipyard shops. Kimber Management Company, Charles Stewart Architects, Nordby Construction Company and C+D worked together as a team from start to finish resulting in a very satisfied client.

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