Buildable Design
Efficient, Productive, and Contemporary
Buildable Design takes maximum advantage of efficient, productive, and contemporary construction techniques.
By partnering with contractors early in the design process, we gain a good understanding of their preferred construction methods and then incorporate as much of their input as is appropriate into our design. This results in a more efficient structure and a lower construction cost.
ELIMINATION OF PUDDLING
High strength column concrete is very beneficial in tall buildings since it allows the use of smaller columns. It often creates a significant construction challenge, however. At each column location, high strength column concrete needs to be “puddled” into the slab to allow vertical load transfer through it.
To eliminate puddling, CKC developed a unique detail. “Stayform” is first wrapped around the column cages to restrain slab concrete from flowing over the columns during the slab pour. High strength column concrete is then poured through the “Stayform” cores during the column pours above, providing the required through-slab continuity. Added rebar at the slab/column joints supplements the load transfer.
This innovative detail eliminates the need for puddling which simplifies construction and reduces the potential for field errors.
Column elimination:
Drophead System
CKC has successfully implemented a slab framing strategy on recent residential and hotel towers that eliminates all internal columns. By increasing slab thickness around the perimeter of the core, slab spans of nearly 40 feet from the central core to the exterior glass line are made possible, providing completely open living units and parking layouts without structural obstructions. Net rentable space is increased, and architectural and interior design flexibility is enhanced.
Another benefit is the improved structural efficiency. With the elimination of interior columns, the majority of a building’s dead load is transferred to the core. This minimizes net tension in the core walls from wind and seismic overturning forces, resulting in substantial rebar reductions. The additional drophead cost is thus more than offset by the savings in core wall reinforcing.
Steel Fiber Reinforced Concrete (SFRC)
The use of Steel Fiber Reinforced Concrete (SFRC) in shear wall link beams simplifies construction without compromising seismic performance. Similar to high-strength rebar, CKC was again a pioneer in SFRC’s use and won several awards in recognition, including another prestigious ENR Top 25 Newsmaker award in 2016.
SFRC increases concrete shear strength and ductility, and eliminates the need for link beam diagonal bars. This speeds construction, lowers steel tonnage and reduces the potential for field errors. SFRC adds a valuable tool to the toolkit of structural engineers practicing in high seismic regions.
Concrete Coupling Beam
High strength ties in foreground
Traditional Grade 60 ties in background
HIGH STRENGTH REBAR
CKC was a pioneer in the use of high-strength rebar and received several awards in recognition of this, including a prestigious ENR Top 25 Newsmaker award for the first use of 100 ksi rebar for seismic confinement.
High-strength rebar improves buildability and reduces steel tonnage in columns, shear walls, and mat foundations, some of the most difficult areas of construction.
Supporting Awards
W Hotel Tower, Bellevue, WA
2020 Second Place Winner, High-Rise Buildings: ACI International
Arrivé, Seattle, WA
2019 Best Project Winner, Residential/Hospitality: ENR Northwest
Tower 12, Seattle, WA
2018 Honors Winner, Multifamily Residential: Concrete Reinforcing Steel Institute
Premiere on Pine, Seattle, WA
2016 Honors Winner, Multifamily Residential: Concrete Reinforcing Steel Institute
The Martin, Seattle, WA
2015 Awards of Merit: Structural Engineers Association of Illinois
The Martin, Seattle, WA
2014 Special Applications: Washington Aggregates and Concrete Association
Avalon Towers, Bellevue, WA
2013 Honors Winner: Concrete Reinforcing Steel Institute
Escala, Seattle, WA
2012 Most Innovative Structure & Juror’s Favorite
Structural Engineers Association of Illinois
Escala, Seattle, WA
2012 National Design Award for Multi-family Housing
Concrete Steel Reinforcing Steel Institute
