By Valerie Hendel | PCS Structural Solutions, Tacoma, WA |
Avid crane watchers may track the progress of Absher Construction Company at the site of the Greater Tacoma Convention Center. The new Marriott-brand Hotel broke ground on August 8, 2017 next to the main convention center at 1500 Commerce Street in downtown Tacoma, Washington. Progress on the tower core and structural steel is rising at a steady pace and can be viewed via Absher’s webcam at https://oxblue.com/open/absherco/551tacomatowers
Ankrom Moisan Architects designed the $120 million-dollar Marriott hotel, the newest high rise in downtown Tacoma. The hotel is expected to address the shortage of beds for visitors drawn by the amenities of the Greater Tacoma Convention Center. The new 24-story hotel adds over 300 rooms, a rooftop pool, two-story ballroom, and other four-star amenities.
How do you design a structure that will dramatically impact the downtown skyline and still respect Tacoma’s character? At 264 feet tall, the hotel will take its place as the second tallest building in Tacoma. Nandita Kamath of Ankrom Moisan describes the concept. “Nestled between the Tacoma Convention Center and a historic landmark, this four-star Marriott represents both Tacoma’s industrial history and its vision of growing into a sophisticated destination city. The design creates a modern environment that embraces the city’s grit and local character, a concept we refer to as raw-fined.”
Structural Engineering Challenges
Being sandwiched on all sides within a vibrant and active city center, the hotel site presents unforgiving constraints to the structural engineering design. The structural engineers at PCS Structural Solutions understood that the structural gymnastics and precision required to address the engineering challenges required a proactive, immersive approach. “Digging deep into reams of existing documents and presenting digestible material was fundamental,” says Jason Collins, principal at PCS Structural Solutions. “It was about continually coming face to face with the architect team, sketching and mapping together to explore the intricacies. We stared at drawings and models and wanted to map it in our minds at an intuitive level.”
The site’s physical realities required thoughtful adroit solutions. To the north, precise engineering would match floors between the hotel and the existing convention center. The two structures had to be tied together yet seismically separate. To the south, yet another seismic separation was engineered, protecting the historic Carlton Center and the new hotel from smashing into each other in an earthquake. The varied uses of the arterial Commerce Street with the Tollefson Plaza and Tacoma Link rail and their unique foundations define the east side. An existing shoring wall for the Convention Center dock sits on Court C on the west side of the site. And perhaps the most resolute site feature is the aquifer layer—a ground layer containing water that runs along the hillside. “The risk was penetrating that layer which would have meant potential long-term leakage,” explains Kevin Rothrock, senior associate and project manager for PCS. “We decided to maneuver over that layer with a tiered design.”
Navigating the complexity of the site conditions and working to accommodate the goals and expectations of a diverse group of users couldn’t be a point A to point B process. While it might have been cost effective to nail down design plans early, success depended on making room for new ideas and change. The structural design approach had to be enormously flexible. Kamath elaborates, “We had to balance the pressure to lock down the structure early on with iterative design and accommodate late changes to the mechanical design.”
Translating information reliably and accurately between teams was critical. BIM (Building Information Modeling) serves as translator of sorts. The architectural design team sends its plans to the structural engineering team who do the math and create their structural design. Their BIM team translates that design into a 3D model. From that model, the architects can see how the structural design overlays the architectural design of the structure. Decisions are made based on this exchange of this documentation. “It’s a given that we rely on our structural engineers for design and calculations, but as BIM (Building Information Modeling) has become our primary means of documentation, we also rely on the accuracy and precision of the structural model because it in turn affects the quality of our documentation,” says Kamath.
The Tacoma Convention Center Hotel represents the successful collaboration and coordination between the highly responsive teams of architects, engineers, construction, and the City of Tacoma. As Tacoma continues to grow and make her mark, its certain that more visitors will experience and enjoy the raw-fined character that makes Tacoma a unique destination. The Tacoma Convention Center Hotel is expected to be complete in 2020.
The project team includes
- Yareton Investment & Management LLC, owner;
- Ankrom Moisan Architects, architecture/interiors;
- Absher Construction, general contractor;
- PCS Structural Solutions, structural engineer;
- AHBL, civil engineer/landscape;
- GeoEngineers, geotechnical engineer;
- Tres West Engineers Inc., MEP design;
- Apollo Mechanical Contractors, mechanical/plumbing engineer;
- Red Hawk Fire & Security, fire protection;
- EC Electric, electrical engineer;
- RDH, building envelope consultant;
- A3 Acoustics LLP, acoustical consultant;
- Lucia Engineering, Inc., shoring design; Smith & Greene, food service;
- ECNW, pool engineer;
- Luma, lighting design.
For more information, visit https://www.pcsstructural.com/projects/tacoma-convention-center-hotel
