ENR: Tricky Excavation Completed for Rainier Square Tower

Engineering News-Record – (August 8, 2019) – Late in July, crews completed the up-to-85-ft-deep excavation for the 850-ft-tall Rainier Square Tower after workers installed a secant pile foundation wall, supported laterally under the neighboring 514-ft-tall high-rise by eight rows of 262 drilled tieback anchors. The system is keeping the occupied office building from turning from a looming tower into a leaning tower. “Deflections on the secant wall have been well below our predicted values,” says David G. Winter, CEO of the taller tower’s geotechnical engineer, Hart Crowser Inc. With the pit complete, The Erection Co. began the first lift of RST’s core of dual steel-plate modules, which will be field-filled with concrete. Construction of the steel frame and core system is expected to take 40% less time than a steel frame with a concrete core (ENR 12/25/17-1/1/18 p. 18).