Jack Christiansen, the structural engineer of the Kingdome and a pioneer of thin-shell concrete roofs, died last month at 89.

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Jack Christiansen of Bainbridge Island, structural engineer of the Kingdome and a pioneer of thin-shell concrete roofs, died in mid-August at the age of 89.

He also worked on the Pacific Science Center, the U.S. Pavilion at the 1974 World’s Fair in Spokane, the Yakima SunDome, Ingraham High School, walkway bridges at the University of Washington, and the truss-supported glass roof at the Museum of Flight.

His crowning feat was the Kingdome roof, at 660 feet in diameter the largest concrete dome in the world. Thousands of sports and concert fans admired his compression ring at the top, where forces converged from the dome’s 40 soaring concrete ribs.

“Visually apparent structural clarity has a universal appeal,” he once wrote. “In a building, this expresses itself in a natural and orderly flow of loads from the top of the building down through the building structure to the foundations.”

That’s equally true of his Spokane landmark, except its tethered roofs pull downward, on a ring surrounding a central pillar.

Seattle’s gray dome was completed in 1976, a modern, multiuse palace like the Houston Astrodome, New Orleans Superdome and the Detroit-area Silverdome.

Though it didn’t have flexing seismic dampers like today’s Sodo stadiums, the Kingdome was robust due to its circular frame and thin roof. Those broad outdoor ramps to the 100, 200 and 300 levels actually doubled as braces for the vertical columns.

The Kingdome was leveled by demolition explosives in 2000 as crowds watched the dust from Beacon Hill and across Elliott Bay.

The premature implosion of the still-functional Kingdome saddened Mr. Christiansen, yet he put it behind him, friends say. He continued to advise fellow engineers, and completed projects including a bridge in Fairbanks, Alaska.

He was born in Chicago and met his wife, artist Sue Hasselquist, at the University of Illinois. He completed a master’s degree at Northwestern University, and the couple moved out west to Puget Sound in a black Ford with their first daughter, Janet Sue.

Structural concrete was still a young technology in 1955when he devised “the eggshell roof” for Evans Pool near Green Lake, says famed Seattle engineer Jon Magnusson, a former colleague. The surface was just 3 inches thick, including rebar, but a clever curvature helped it stretch 100 feet.

Mr. Christiansen went on to develop some 75 thin-shell projects. He also engineered the Bainbridge High School grandstands with his son John, the project architect, in 1990, his daughter Nelda Swiggett said.

In the early 1970s, Jack and Sue brought their five children to Europe for a 10-week trip in a Volkswagen van, Swiggett recalls. They hiked the Alps, drew color sketches, pilgrimaged to classical Greek and Roman sites, and toured buildings by Antoni Gaudi in Spain, including the Basílica de la Sagrada Família.

Mr. Christiansen loved to explore the outdoors, and eventually he summitted the 100 highest peaks of the Olympic Mountains, relatives say.

On the day Mount St. Helens erupted in 1980, Mr. Christiansen led a group climbing nearby Mount Adams. The sky darkened and rocks fell. Static in the volcanic cloud made his ice ax shiver.

“He wasn’t only about getting to the top of the mountains,” Swiggett said. “He was about getting into the wilderness, navigating with a map and compass, and finding adventure. If you want to bushwhack, you go climbing with Jack.”

Even in retirement he volunteered on local projects, such as designing public stairways to Bainbridge Island beaches, his daughter said.

Mr. Christiansen was preceded in death by his wife in 2010. He is survived by daughters Janet Jorgenson of Fairbanks, Nelda Swiggett of Seattle, Karin Kajita of Shoreline; sons John Christiansen and Robert Christiansen of Bainbridge Island; and six grandchildren.

A private service has been held. Donations may be made to the Bainbridge Island Land Trust or the Sierra Club.