Herman D.J. Spiegel GRD ’55, a beloved teacher and engineer who served as dean of the Yale School of Architecture when it first became a professional school of its own, died Sunday at Yale-New Haven Hospital.

The cause of death was complications from multiple myeloma, said Spiegel’s son William, whose father was 83.

Although he trained as an architect at first, Spiegel’s professional and academic lives were defined by his passion for structural engineering. Tellingly, in an article eight years ago in the Yale architecture journal Perspecta, he bemoaned trends in the field that had made technical design seemingly secondary to aesthetic considerations.

“Many architects avoid thinking about structure,” Spiegel wrote. “They prefer to ignore gravity, wind, seismic, or thermal forces. But to disregard these real forces is to miss architectural opportunities.”

In his professional work, Spiegel missed few such opportunities. And at Yale, he was able to balance a love for the technical with a gregarious goodwill. No other engineer has ever served as dean of the Yale School of Architecture; few other deans have garnered so much affection during their tenures.

William Spiegel echoed the sentiments of many of his father’s friends and colleagues when he called him “one of the happiest guys anyone’s ever known.” But that is not to say that Spiegel was an easy teacher.

Architecture professor Alexander Purves ’58 ARC ’65, who took a course in structures from Spiegel, recalled his former teacher as a stern but inspiring taskmaster.

“It was a difficult course, and I had to learn to use a slide rule, believe it or not,” Purves said. “But he was such a joy to be around — he was very humorous and very energetic.”

Almost no one could have been better-suited to teach structural engineering than Spiegel. As a dean, though, Spiegel was an unlikely pick.

“There would always be people who thought that an engineer shouldn’t be dean of an architecture school,” Purves said.

But those people were largely silenced by the administrative troubles that emerged under Charles Moore’s leadership. Moore was Spiegel’s predecessor, but his tenure as dean of the faculties in design and planning (the architecture school was, at the time, still combined with the School of Art) was plagued by student unrest and other difficulties.

Yale President Kingman Brewster tapped Spiegel at first to serve in an interim capacity as dean of the faculties in design and planning in late 1970. By 1971, Spiegel was given full dean status; by 1972, he was the first dean of the newly independent Yale School of Architecture. He would serve in that capacity until 1976 and was acting dean in the spring of 1982.

John Jacobson ARC ’70, who studied under and ultimately worked with Spiegel and is now associate dean of the School of Architecture, recalled that Spiegel was an open and forthcoming administrator.

“He solicited faculty opinion constantly,” Jacobson said. “All decisions were made together, and everyone felt like they had a real voice.”

Even if Spiegel was open to faculty input on virtually all matters, though, he was more hesitant to hear the concerns of alumni. Graduates who were hiring students would often complain that Yale architects were not the easiest to control.

But, Purves recalled, Spiegel’s quick wit served him well; he would respond to such grievances by telling the alumni that “we’re not training your employees — we’re training your competitors.”

Spiegel himself was a successful practicing structural engineer. The firm he established in 1956, Spiegel Zamecnik & Shah Inc., today has offices in New Haven and Washington, D.C.

Above all, however, Spiegel is remembered by those who knew him as a wonderful friend. Robert A.M. Stern ARC ’65, the current School of Architecture dean, fondly recalled Spiegel’s visits to the school after his retirement.

“He was one of our most loved faculty members,” Stern said. “We always liked seeing him here, and we will miss him.”

Herman Spiegel was born Dec. 31, 1924, in Boston, Mass., and is survived by his wife of 51 years, Sally; two sons, Robert and William; and four grandchildren, as well as other relatives.