FACT: “No sooner did the Tacoma Narrows Bridge—the world’s third longest suspension bridge, and the pride of Washington State—open in July 1940 than it earned its epitaphic nickname, “Galloping Gertie.” The 4,000-foot structure, its main span reaching 2,800 feet, twisted and bucked in the wind. The pronounced heave, or more technically speaking the longitudinal undulation, caused some automobile passengers to complain of seasickness during crossings. Others observed oncoming cars disappearing from sight as if traveling a hilly country road. By November 7, amid 39-mile-an-hour winds, the $6,400,000 bridge wobbled and flailed, then rippled and rolled, then twisted like a roller coaster, until in its final throes it plunged, with a beastly roar, 190 feet into the waters of Puget Sound.” -Siobhan Roberts, from chapter 1 of Wind Wizard
We invite you to read the full chapter online at:
Alan G. Davenport and the Art of Wind Engineering
by Siobhan Roberts
With Wind Wizard, Siobhan Roberts brings us the story of Alan Davenport (1932-2009), the father of modern wind engineering, who investigated how wind navigates the obstacle course of the earth’s natural and built environments–and how, when not properly heeded, wind causes buildings and bridges to teeter unduly, sway with abandon, and even collapse.
In 1964, Davenport received a confidential telephone call from two engineers requesting tests on a pair of towers that promised to be the tallest in the world. His resulting wind studies on New York’s World Trade Center advanced the art and science of wind engineering with one pioneering innovation after another. Establishing the first dedicated “boundary layer” wind tunnel laboratory for civil engineering structures, Davenport enabled the study of the atmospheric region from the earth’s surface to three thousand feet, where the air churns with turbulent eddies, the average wind speed increasing with height. The boundary layer wind tunnel mimics these windy marbled striations in order to test models of buildings and bridges that inevitably face the wind when built. Over the years, Davenport’s revolutionary lab investigated and improved the wind-worthiness of the world’s greatest structures, including the Sears Tower, the John Hancock Tower, Shanghai’s World Financial Center, the CN Tower, the iconic Golden Gate Bridge, the Bronx-Whitestone Bridge, the Sunshine Skyway, and the proposed crossing for the Strait of Messina, linking Sicily with mainland Italy.
Chronicling Davenport’s innovations by analyzing select projects, this popular-science book gives an illuminating behind-the-scenes view into the practice of wind engineering, and insight into Davenport’s steadfast belief that there is neither a structure too tall nor too long, as long as it is supported by sound wind science.