ccording to the publication, the mixed-use Rainier Square Tower is the first structure to utilize concrete-filled composite plate shear wall (CPSW) construction. Instead of a conventional concrete wall reinforced with large-diameter rebar, the system uses 0.50- or 0.75-inch-thick steel plates. The plates are connected with 1-inch-diameter steel cross-ties running horizontally and vertically on 12-inch center grids. The steel plates and cross-ties sandwich the concrete, thereby improving stability and preventing inward local buckling.
 
Local engineers Magnusson Klemencic Associates collaborated with the Charles Pankow Foundation on research and testing of the CPSW system. The steel plates support faster core and floor level turnaround, which allowed the project to be completed on an expedited schedule — 10 months in this case. 
 
Concrete Products has more here.