Cheerleaders for steel buildings with modular composite plate-steel cores have found ways to simplify the novel system for high-rises. Design guidelines are coming out this year. And standards are coming in a couple of years.
At the heart of the system are “sandwich” panels of steel plate, joined by tie rods and field-filled with plain concrete. Recent research on seismic and wind behavior, co-sponsored primarily by the Charles Pankow Foundation and the American Institute of Steel Construction (AISC), has determined that tie-rod spacing can be 18 in. on center, rather than 12 in., say Michel Bruneau, director of the University at Buffalo’s seismic engineering laboratory, and his co-lead researcher Amit Varma, director of Purdue University’s engineering lab.“We both demonstrated that these walls can sustain inelastic deformations in a ductile way,” Bruneau says.
The findings translate to a 30% reduction in the number of rods, which means 30% fewer fillet welds, says Ron Klemencic, Magnusson Klemencic Associates’ chairman and CEO, and the mastermind of the system. MKA used the conservative 12-in. spacing for its first project with the system, Seattle’s 850-ft-tall Rainier Square Tower, set to open in September.
The design specification for the rectilinear sandwich panel and a C-in-plan “corner” version is coming out this year as part of the NEHRP Seismic Provisions. The provisions are on course for adoption in the 2022 editions of the AISC 360 Specification for Structural Steel Buildings and AISC 341 Seismic Provisions for Structural Steel Buildings.
Design and detailing guidelines of connections for both seismic and nonseismic applications are expected next year. Ongoing research focuses on bolted splices and wall-to-foundation connections.
Tests at Purdue also show the panels perform well without fire protection, says Varma. A report containing fire resistance and performance provisions for the composite walls is set to be published this month.
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