In 1910, the world’s reigning skyscraper was the Metropolitan Life Tower in Midtown Manhattan. Standing at 50 stories and 700 feet tall, the tower eclipsed the previous record holder, Manhattan’s Singer Building, by 88 feet and three stories. Architecturally, the Met tower bore a strong resemblance to the 323-foot San Marco Campanile in St. Mark’s Square in Venice, Italy, a 16th century structure admired by Met Life’s president, John Hegeman.
Chief architect for the Metropolitan building complex was Pierre L. Lebrun, and the legendary Corydon T. Purdy was the daring structural engineer. The Chicago-based Purdy, known today as the “father of skyscrapers,” began his work during the infancy of skyscraper construction in the late 1880s before moving his firm, Purdy & Henderson, to New York City in the 1890s. At the time, Purdy was involved in the design of more skyscrapers than anyone else in the world.
In Purdy’s time, the term “skyscraper” described any building that relied on iron or steel framework (skeleton) rather than thick, heavy masonry walls, to carry a tall building’s loads. Reinforced-concrete frames were also included in the description. The term gained popularity after the completion of Chicago’s Home Insurance Building in 1885, though the building was only 10 stories and 140 feet tall. Designed by civil-structural engineer William Jenney, the Home Insurance Building is still remembered as the world’s first skyscraper, though it was demolished years ago.
Architectural historians Landau and Condit (“Rise of the New York Skyscraper,” 1996) wrote: “Due to developments in the iron and steel construction of skyscrapers that went well beyond the general knowledge of most architects, the engineering profession had achieved a new prominence and now raised its voice to affect changes in the building laws and to ensure engineers played a greater role in the construction of high buildings.”
Of particular concern were lateral loads — wind and seismic forces — and the ramifications of differential temperature changes, as well as nuances of column shortening. Engineers were needed to provide sophisticated design analysis and detailing of such innovations as beam-column moment connections, beam-column knee bracing, full-bay X-bracing, and thin masonry or concrete shear walls — all components invented to stabilize buildings while still allowing for the desired architecture.
Instead of architects depending on large steel companies for their steel design needs and structural drawings as they had in the past, professionally trained consulting engineers were used extensively. The Wisconsin-born Purdy was the early leader and champion of this movement; he also led efforts to encourage American engineering colleges to offer advanced steel and multi-story design coursework. After its presentation at the 1904 national convention of the American Institute of Architects, his paper, “The Relation of the Engineer to the Architect” (Proceedings of AIA, 1904), became the seminal document of the industry.
In January 2010, the modern king of skyscrapers, the Burj Khalifa in Dubai, was completed at approximately four times the height of the Met Life Tower a century earlier. The Dubai tower, like the tallest buildings of the past, was made possible by innovative and ingenious structural engineering. What heights will our structures reach in the next 100 years? And will the structural engineers responsible for them remain as invisible as they were in days gone by? That’s up to you.
Richard G. Weingardt, P.E., is CEO and chairman of Richard Weingardt Consultants, Inc., a Denver-based structural engineering firm. He can be reached via e-mail at firstname.lastname@example.org.