ArchitectGuerin Glass Architecture
ContractorAlbert C. Kobayashi, Inc.
Waikiki. The Ritz-Carlton. The former is one of the world’s premier vacation destinations and the latter is synonymous with luxury development. The union of these two is The Ritz-Carlton Residences Waikiki Beach. Constructed in two phases, this project is the largest new resort development in recent times and includes approximately 900,000 SF in two complementary 38-story towers, each 350 ft. tall. Phase 1 of this luxury hotel and condominium project opened to the public in July 2016 and has become one of Hawaii’s most sought-after luxury residential addresses offering the ultimate in resort-style living with unobstructed views of the Pacific Ocean, world-class design and access to legendary amenities and services provided by one of the world’s best hoteliers.
Both towers sit atop an eight-story podium that includes parking on levels 2 to 5; fitness amenities and administrative offices on level 6; and the main lobby, pools, restaurant and other amenities on level 8. The hotels also include three restaurants and street level commercial space as well as parking and back of house / supportive spaces.
Designed as a luxury product on a challenging site, the goal was to maximize the value of each residential level. BASE worked closely with the design team, contractor and owner to develop a cost-effective structural approach that worked within site constraints yet allowed for maximum flexibility for the architect to lay out the residential and activity floors to create the most attractive, functional and sellable units possible.
The Phase 1 and 2 towers share common spaces at the podium floors, which needed to be separated by seismic expansion joints. During the initial design of Phase 1, BASE collaborated with the architect to ensure that the expansion joint was designed with corbels along the floor edge beams and columns in order to support the future Phase 2 tower, even though its design was only in its very early stages. This proactive approach avoided the need to provide new columns and new foundations along the expansion joint that might appear to be an afterthought or retrofit to support the final Phase 2 building configuration.
In addition to design and construction administration, BASE also performed code-required structural special inspection services. This added involvement allowed BASE to quickly address contractor inquiries during the construction of this very complicated project.
The Science and Design of Structural Engineering
The joint development and unique site geometry were encumbered by numerous easements including extensive vehicular maneuvering onsite for an adjacent retail loading area and a large underground electric utility power station. Each building required large transfer trusses to accommodate these constraints. On Phase 1, a 120-ft. span transfer truss between floors two and four provided large clear areas for vehicular maneuvering and on Phase 2, a 64-ft. span transfer truss between floors 27 and 28 will carry 10 upper level residential floors over the power station.
Offset foundations and columns, as well as sloping columns, were incorporated throughout the project to shift support locations through varying floor layouts that change 18 times through the 38 tower floors. Those transitions also allowed for large open spaces at the ground floor for drop-off and loading dock areas. Podium level 8 utilizes a number of transfer girders to transfer tower walls and columns onto a different set of podium level columns and walls. All told, there are 38 transfer girders and 66 column transitions in the project, with every column in the tower transitioning somewhere before reaching its supporting foundation. This transition of vertical elements at level 8, with the use of deep post-tensioned transfer girders, allowed for the most efficient design of sellable spaces at podium and tower levels.
In order to maximize the number of floors within the 350'-0" height limit in Waikiki, thin 7" post-tensioned concrete slabs were used in the parking and tower levels. Large double-story penthouse atrium spaces were achieved by hanging the top floor plates with more than 32 steel “skyhook” columns from the roof level. Additional column-free wall areas were also created at the upper floors by hiding over 60 compact steel columns within window mullions and wall partitions.