A three-person peer-review panel has given a green light to the cutting-edge structure for Seattle’s Rainier Square Tower, an 850-ft-tall “proof of concept” for a new core system, which will have a tied dual-plate shear wall, field-filled with rebar-less concrete. The building team predicts construction will take some nine months less than a conventional tower with a steel frame around a reinforced concrete core. Steel erection is set to begin in September. A certificate of occupancy is expected in April 2020.