What is the overall wall thickness in the Rainier Square Tower project?  How thick are the plates?  What are the material strengths?

Total Wall Thickness:

21 inches thick at the top - 45 inches thick at the base

Faceplate:

• ASTM A1043 Grade 50, Fy = 50 ksi
• ½ inch thick throughout
• ¾ inch thick at localized high-demand regions

Cross-ties:

• Rod Fy = 55 ksi
• 1 inch diameter
• 12 inches on-center

What is the relative site fabrication (erector) intensity of this system when compared to other steel systems? How is the increased site work affect project schedule and cost?

It is expected that the erection crew would be larger than a conventionally framed building. As with any project, the crew size would be specific to the job and highly dependent on the number of picks required between the non-lateral system gravity steel framing as compared to the lateral system core elements.  That being said, the reduction of all site labor is expected to be a less. The lack of site-placed temporary formwork and reinforcing bars has a significant impact on site labor intensity.

Real-World Application | Rainier Square Tower

For the case of Rainier Square, depending on location in the building, the steel erection crew size varies. It is estimated to be anywhere between 50% to 100% larger than the size required to erect just the gravity system for this project.  The overall project schedule and cost was reduced significantly through the use of the SpeedCore system.

Are the plates able to be joined by field bolting or welding? What specifically is done to ensure proper fit-up in the field? Are there any special tolerance considerations?

Field welded or  bolted connections can be developed for a particular project's needs. Given that all the components of the core are pre-fabricated, a tight shop tolerance is needed to ensure proper fit up in the field for either connection type.

Real-World Application | Rainier Square Tower 

The Rainier Square Tower project utilizes a field splice weld capable of developing the tensile strength of the faceplates.

Several options were studied to connect the slab to the wall modules and provide diaphragm continuity: welded rebar to the faceplates, ledge angles with shear connectors, and pre-drilled holes for which rebar would be inserted prior to casting the wall and slabs.

Rainier Square: The chosen mechanism for Rainier Square was pre-drilled holes for which rebar would be inserted prior to casting the wall and slabs.  

Is there any special machinery required to fabricate a SpeedCore module?

Specially trained staff or specific machinery are not required for fabricating a SpeedCore module. As with any larger fabricated element, a fabricator would need to coordinate adequate shop working areas and crane capacities.

In the Rainier Square Tower project, where are the modules spliced? Where are the concrete cold joints in the system?

As depicted in the rendering of the SpeedCore system, the splices are made at approximately +4'-0" above finished floor, just as a column would be spliced. The concrete contractor plans to fill the walls on a floor-by-floor basis, roughly matching the elevation of the steel plate horizontal splices.

What is the order of erection and concrete placement?

As with other construction aspects of the SpeedCore system, order of module erection and concrete placement should be evaluated on a project-by-project basis. Steel erection can advance up to four stories beyond the last concreted level per OSHA.

Real-World Project | Rainier Square Tower

The panels that comprise the core are erected in sequence with the columns. The panels are connected to the core boundary columns and erected one level at a time. Concrete is placed after the panels and columns have been erected, plumbed, and welded.

What qualities of concrete are necessary to achieve the desired behavior in concrete placement and structural behavior?

Real-World Application | Rainier Square Tower

10 ksi concrete strength was required by design; however the cylinder breaks are coming in at 14-15 ksi. Concrete strength and stiffness were integral to the design of the system based on the lateral demands of the building.  In terms of placement, depending on the planned methods for placement, a highly flowable mix that can adequately consolidate into all voids within the panels is required.

Would recycled aggregate be a feasible option for the concrete infill?

Architects are often looking to use high recycled content in their building materials. Given the highly variable material properties for recycled aggregate, it's not recommended to use recycled aggregate in the concrete mix for critical lateral systems that are stiffness controlled.

Can utilities be placed within the walls?

Similar to the coordination efforts required for conventional reinforced concrete walls, utility penetrations are coordinated in the design phase. In this system, the openings are incorporated into the pre-fabrication of the panels. Utilities are run perpendicular through the plates and concrete infill. The lack of internal reinforcing in SpeedCore should make the accommodation of utilities less of a challenge than placing them in a conventional reinforced concrete shear wall.

A lot of the SpeedCore construction process takes place under the cover of steel deck because its timeline is so closely aligned with floor framing. This decreases workers' exposure to materials that might drop from above.