northanger (northanger) wrote,
northanger
northanger

When the Levee Breaks

thanks to lady </a></b></a>elnigma who noticed george is dazed & confused.

excellent essay (via hyperstition) by Lee Harris about evolution vs. creationism that avoids being one dimensional. reading it started thinking about engineers & galloping gertie — barely five months old, on 07-Nov-1940 the Tacoma Narrows Bridge collapsed after tortuously tying itself in knots. "the most spectacular failure in bridge engineering history" collapsed because of the wind.

the brooklyn bridge was the first steel-wire suspension bridge; construction began in 1869 & the bridge was opened for use on 24-May-1883.

At the time the bridge was built, the aerodynamics of bridge building had not been worked out. Bridges were not tested in wind tunnels until the 1950s - well after after the collapse of the Tacoma Narrows Bridge in the 1940s. It is therefore fortunate that the open truss structure supporting the deck is by its nature less subject to aerodynamic problems. Roebling designed a bridge and truss system that was six times as strong as he thought it needed to be. Because of this, the Brooklyn Bridge is still standing when many of the bridges built around the same time have vanished into history and had been replaced.

Lessons From the Failure of a Great Machine

At the time the 1940 Narrows Bridge failed, the small community of suspension bridge engineers believed that lighter and narrower bridges were theoretically and functionally sound. In general, leading suspension bridge designers like David Steinman, Othmar Amman, and Leon Moisseiff determined the direction of the profession. Very few people were designing these huge civil works projects. The great bridges were extremely expensive. They presented immensely complicated problems of engineering and construction. The work was sharply limited by government regulation, various social concerns, and constant public scrutiny. A handful of talented engineers became pre-eminent. But, they had what has been called a "blind spot."

That "blind spot" was the root of the problem. According to bridge historian David P. Billington, at that time among suspension bridge engineers, "there seemed to be almost no recognition that wind created vertical movement at all."

The best suspension bridge designers in the 1930s believed that earlier failures had occurred because of heavy traffic loading and poor workmanship. Wind was not particularly important. Engineers viewed stiffening trusses as important for preventing sideways movement (lateral, or horizontal deflection) of the cables and the roadway. Such motion resulted from traffic loads and temperature changes, but had almost nothing to do with the wind.

This trend ran in virtual ignorance of the lessons of earlier times. Early suspension bridge failures resulted from light spans with very flexible decks that were vulnerable to wind (aerodynamic) forces. In the late 19th century engineers moved toward very stiff and heavy suspension bridges. John Roebling consciously designed the 1883 Brooklyn Bridge so that it would be stable against the stresses of wind. In the early 20th century, however, says David P. Billington, Roebling's "historical perspective seemed to have been replaced by a visual preference unrelated to structural engineering."

Just four months after Galloping Gertie failed, a professor of civil engineering at Columbia University, J. K. Finch, published an article in Engineering News-Record that summarized over a century of suspension bridge failures. In the article, titled "Wind Failures of Suspension Bridges or Evolution and Decay of the Stiffening Truss," Finch reminded engineers of some important history, as he reviewed the record of spans that had suffered from aerodynamic instability. Finch declared, "These long-forgotten difficulties with early suspension bridges, clearly show that while to modern engineers, the gyrations of the Tacoma bridge constituted something entirely new and strange, they were not new--they had simply been forgotten."

An entire generation of suspension bridge designer-engineers forgot the lessons of the 19th century. The last major suspension bridge failure had happened five decades earlier, when the Niagara-Clifton Bridge fell in 1889. And, in the 1930s, aerodynamic forces were not well understood at all.

"The entire profession shares in the responsibility," said David Steinman, the highly regarded suspension bridge designer. As experience with leading-edge suspension bridge designs gave engineers new knowledge, they had failed to relate it to aerodynamics and the dynamic effects of wind forces.

in engineering, the Tacoma Narrows Bridge is referred to as an example of DESIGN FAILURE. as a quality assurance engineer i hear something completely different when someone starts talking about INTELLIGENT DESIGN. engineers build things for people & the things we build must work. if we design a bullet-proof vest we must assure that it stops bullets & we must assure that our production processes maintains a standard of quality. the Deming Prize is awarded by the Union of Japanese Scientists and Engineers (JUSE) who created the prize in appreciation of Dr. W. Edwards Deming contributions in implementing quality control in Japan after WWII.

The Paradigms of Quality: Evolution and Revolution in the History of the Discipline (PDF):

It was in Japan however where local adaptations to the business environment were strongest, and where the seeds of the next paradigm were sewn most strongly. Decimated by World War II, Japan's industry had to be built from the ground up. With few precious resources to draw upon, Japan had to rely on its own industrial creativity to rise to a level of competitiveness in commerce. Japan had done little prior to World War II concerning the discipline of quality. In the 1940's several important organizations were formed: Japan Management Association (1942), Japan Standards Association (1945), and the Union of Japanese Scientists and Engineers (JUSE) (1946); all aided in the reconstruction of the country (Nonaka, 1995). Americans on-loan from Bell Laboratories introduced JUSE members to Shewhart's 1931 book and the Z.1, 2, and 3 quality control standards, and several members became intrigued by the concepts. In 1950 JUSE Managing Director Kenichi Koyanagi requested Deming, who had been in Japan several year previous to aid in census-taking, to deliver lectures concerning quality control methods (Walton, 1986). Deming's courses included "Training of Quality Control Engineers and Statisticians in Industry" and several lectures for top management (Kilian, 1988). It was here that Deming told them "...they could capture markets the world over within five years" and reminiscing "They beat that prediction. Within four years, buyers all over the world were screaming for Japanese products" (Walton, 1986, p. 14).

You can install a new desk, or a new carpet, or a new dean, but not quality control. Anyone that proposes to 'install quality control' unfortunately has little knowledge about quality control. Improvement of quality and productivity, to be successful in any company, must be a learning process, year by year, top management leading the whole company —W. Edwards Deming

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