In This Section
How Does It Work?
The fundamental unit is a sandwiched panel of steel plates that are subsequently filled with concrete. Cross-connecting tie rods hold two structural steel plate in place, supporting the wall panel before the concrete is poured. The steel panels in SpeedCore construction can support up to four floors of steel floor and metal decking even before they are filled with concrete.
After erection, these panels are filled with concrete and left in place, providing strength and stability along with a rapid erection procedure that doesn’t rely on the complex and time-consuming process required for a reinforced concrete core: setting formwork, installing reinforcing steel, placing embedded plates, installing sleeves and block-outs, and placing and curing concrete for each level of the core.
What is the function of the steel plate? What is the function of the concrete?
During construction, the steel faceplates with the steel cross-ties provide stability under construction loading during erection prior to the concrete infill being placed. The plates, by their nature, also provide permanent formwork for the concrete. After the concrete infill has cured, the plates, the cross-ties and the concrete act compositely with the plates. The steel acts as wall reinforcement and the primary resistance to tension and shear demands on the lateral system. The concrete infill, working compositely with the steel faceplates, provides overall flexural and shear stiffness to the structure with the confined concrete having the ability to resist larger overturning compressive loads under lateral demands.
Who is responsible for designing the plate for the various loading conditions?
The design responsibility of the phased loading of the module as a whole, the plate, and the associated connections should be evaluated and discussed directly with the contractors involved. Most importantly, the conclusion of responsibility should be delineated in the final contract. Due to the special nature of the system, there should be open communication about design responsibility to ensure a successful project.
Real-World Application | Rainier Square Tower
For the case of the Rainier Square Tower project, the design considers four stories of the empty module advancing ahead of the concrete fill operation. The contractor's preferred erection logistics were considered in the design of the steel faceplates along with cross-tie size, spacing, and attachment. In addition, the four floors limitation was driven by OSHA requirements. 1926.754(b)2) states: "At no time shall there be more than four floors or 48 feet (14.6 m), whichever is less, of unfinished bolting or welding above the foundation or uppermost permanently secured floor, except where the structural integrity is maintained as a result of the design."
At what building height would an owner begin to see measurable savings to a project's bottom line?
A savings of cost and schedule can be realized in buildings five stories and taller. The overall project savings primarily comes from the reduction in the construction schedule and the more accurate tolerances in steel erection as opposed to concrete placement. As the construction schedule is highly building-dependent in terms of geometry and complexity as well as local construction practices and material availability, the measurable savings is likely not to be solely tied to building height.
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