hotels_marriott_poolThe $43 million Waterfront Marriott Hotel is an essential component of the downtown Seattle revitalization plan “inviting back” the public to the Port of Seattle as a place to live, work, and play. Opened in 2003, the hotel plays a key role in providing improved public amenities, employment opportunities, dwellings, and open space.

One of Seattle’s two waterfront hotels, this eight-story, 316,000-square-foot facility, has three guest wings, and all 358 guestrooms overlook Elliott Bay with magnificent views of the Puget Sound and the Olympic Mountain range. Within walking distance of major attractions and shopping destinations, the hotel features the 8,200-square-foot Grand Pacific Ballroom, an indoor/outdoor swimming pool, a gourmet restaurant, retail space, and two underground parking levels for 116 cars.

hotels_marriott_waterfrontPanoramic views of Puget Sound and the Olympic Mountains from an adjacent public park on a sloped site limited the building height to 86 feet above grade. The design team identified cast-in-place concrete as the only floor system that could meet the floor height limit and squeeze the required number of above-grade levels to make the project feasible. A post-tensioned 7-inch-thick flat plate provided an economical structural system that achieved the necessary floor to floor clearance without blocking the park views. Slabs are reinforced at supporting 18-inch columns with mild rebar and stud-rails for added shear capacity. Half the guestrooms feature private balconies achieved by cantilevering the post-tensioned slab.

hotels_marriott_alleyConcerned with noise from the adjacent Burlington Northern railroad corridor, the design team employed a 250-foot long concrete shear wall cast along the rail corridor. The wall provides acoustical separation from the noisy railroad traffic and also serves as a natural fire barrier. This long wall possessed very high relative stiffness, but KPFF Consulting engineers carefully laid out the remaining shorter structural walls to mitigate any torsional imbalance, while keeping the most effective guestroom layout. Typically 12-inches thick, the shear walls and boundary elements were carefully detailed to provide ductile performance under earthquake and seismic loads.

A combination of concrete spread footings, mat foundations, and auger-cast concrete piles anchored to reinforced concrete pile caps made up the column and shear wall foundations. An economical alternative to steel piles, concrete piles reduced serious noise and vibration concerns associated with driving steel piles. The lowest level of the two-story basement is 21 feet below grade and 15 feet below mean sea level. Alternative membrane and waterproofing systems were considered to provide an effective integral waterproofing system, but were determined to be uneconomical and required excessive construction time. All below-grade construction and control joints included sodium bentonite waterstops and a post-injectable grout hose system to seal and waterproof.

hotels_marriott_constructioApproximately 17,000 cubic yards of concrete was used in construction with design strengths from 3,000 to 6,000 psi. Higher strengths were used for post-tensioned slabs and heavily loaded walls and columns. At each level, the individual wings represented separate placement operations with a typical “pour-size” of 12,000 square feet. The Seattle Waterfront Marriott hotel marks the second application of the world’s heaviest concrete, originally developed for radiation shielding at the Seattle Cancer Care Alliance. This 350-pound-per-cubic-foot heavyweight concrete provides a unique counterbalancing system for elevator imposed uplift forces. This resulted from locating elevator equipment in the basement instead of the roof. The exterior of the hotel features 14,000 square feet of architectural precast concrete panels and 25,000 square feet of patterned exposed concrete. The rooftop “seascape” design was rendered with 47,000 colored concrete and recycled glass pavers.

This durable concrete project, completed in 18 months, resulted in a thriving neighborhood contributing to Seattle’s economic and cultural vitality.

Credits

Owner (during development):
Marriott International, Washington, D.C.

Developer:
Wright Hotels and Frank Finneran & Co., Seattle, Washington

Architect:
FMSM Design Group, Albuquerque, New Mexico

Architect (construction phase):
Jensen/Fey Architecture and Planning, Seattle, Washington

Structural Engineer:
KPFF Consulting Engineers, Seattle, Washington

Project management:
Sutor Consulting, Seattle, Washington

General contractor:
Turner Construction Co., Seattle, Washington

Interior designer:
Banik-Cumby, Philadelphia, Pennsylvania

Designer (The Fish Club):
Duncan & Miller Design, Dallas, Texas