PLATEAU-WAVE PHENOMENON (I)

Chapter 2 reviews answers to the question of what is light, starting with the ancient Greeks and ending in 1900 with the wave concept of Maxwell’s electrodynamics. For some ancient Greeks, light consisted of atoms emitted from surface of the object, whereas for others it was fire that either entered into or was emitted by eyes, although the latter possibility was effectively eliminated around the year 1000. Competing proposals well after then were that light is either a wave phenomenon or consists of particles, with Isaac Newton’s corpuscular (particle) theory prevailing by the end of the 1600s over the wave concept championed by Christiaan Huygens, who published the first estimate of the speed of light. In the early 1800s, Thomas Young’s two-slit experiment proved that light was a wave, a concept codified and firmly grounded through Maxwell’s theory of electromagnetic waves.

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Canal Wave Oscillations from Expansion of I-84 Bridge in Boise, Idaho

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/2309-19 ◽

2012 ◽

Vol 2309 (1) ◽

pp. 200-205

Author(s):

William Rahmeyer ◽

J. M. Clegg ◽

S. L. Barfuss

Keyword(s):

New York ◽

Physical Model ◽

Unique Solution ◽

Wave Phenomenon ◽

Bridge Columns ◽

Bridge Abutments ◽

Wave Problem ◽

Model Study ◽

Bridge Crossing

Recent improvements and the widening of the I-84 Bridge crossing of the New York Canal in Boise, Idaho, have increased the number of bridge columns from 28 to 60. The resulting structure has two parallel rows of columns that extend across the width of the bridge longitudinally within the canal. After the widening of the bridge and addition of the bridge columns, the canal began experiencing an oscillating wave phenomenon that originated from the bridge columns and caused erosion of upstream and downstream canal banks and bridge abutments. A physical model study was conducted to investigate the wave phenomenon and determine what modifications to the columns or canal would be necessary to prevent the wave oscillations. The physical model was successful in simulating the wave phenomenon, and four different modifications for resolving the wave problem were tested in the model. A unique solution was found that used precast nose cones attached to selected columns. The nose cones have been installed in the prototype bridge crossing, and no wave oscillations have occurred since installation. This paper discusses the study to simulate the wave phenomenon and the four modifications that were evaluated to reduce or prevent wave oscillations.

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