A team in earthquake-prone Seattle is daring to deliver an 850-ft-tall “proof of concept” for a composite structural-steel frame, instead of a steel frame around a reinforced concrete core. For the players, it’s not just about eliminating concrete’s bedeviling rebar congestion and potentially dangerous jump forms. And it’s not just about keeping ironworkers and concrete casters out of each other’s hair.

The team gearing up for the $570-million Rainier Square Tower is immediately motivated by the prospect of slashing 40% off the time required to build a standard steel frame with a concrete core. The overarching aim, however, is to usher in an era of speedier, safer and better office-tower construction—everywhere.