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San Francisco in San Francisco City and County, California — The American West (Pacific Coastal)
 

Resisting the Twisting

 
 
Resisting the Twisting Marker image. Click for full size.
By Cosmos Mariner, July 8, 2014
1. Resisting the Twisting Marker
Inscription.  Ever since the modern suspension bridge was invented in the early 1800s, one of the biggest challenges engineers have faced is preventing these flexible structures from moving too much in the wind.

A storm on December 1, 1951, caused the Golden Gate Bridge to twist and vibrate enough to cause some minor damage, so the Bridge was retrofitted from 1953 to 1954. The retrofit added new bracing across the bottom, connecting the two steel trusses that support the roadway deck. This change increased the Bridge's twisting, or torsional, stiffness.

Twist each of these models to feel which one is stiffer

Original Bridge Deck Shape
This is a scale model of a 500-foot (152-meter) length of the Golden Gate Bridge, without the roadway on top. The trusses on the sides, along with the framing on top that supports the roadway, form an upside-down U-shape.

Retrofitted Bridge Deck Shape
This model shows the Bridge deck today. The difference from the original design, at left, is the addition of bottom bracing. The cross section is a closed shape.
 
Location. 37° 
Marker detail: The new bracing is visible in the bottom level image. Click for full size.
Courtesy Golden Gate Bridge, Highway and Transportation District
2. Marker detail: The new bracing is visible in the bottom level
48.488′ N, 122° 28.441′ W. Marker is in San Francisco, California, in San Francisco City and County. Marker can be reached from the intersection of U.S. 101 and Lincoln Boulevard. Touch for map. Marker is located along the Battery East trail, about 1/10 mile west of the Battery East parking lot. Marker is in this post office area: San Francisco CA 94129, United States of America. Touch for directions.
 
Other nearby markers. At least 8 other markers are within walking distance of this marker. The Era of Earthworks Batteries (a few steps from this marker); Fort Point National Historic Site (about 700 feet away, measured in a direct line); The Golden Gate Bridge: Vision, Genius and Expert Care (about 700 feet away); Fort Point (approx. 0.2 miles away); Crissy Field (approx. 0.2 miles away); Setting A Deadly Obstacle Course (approx. 0.2 miles away); Men of Vision (approx. 0.2 miles away); Castillo de San Joaquin (approx. 0.2 miles away). Touch for a list and map of all markers in San Francisco.
 
Also see . . .
1. Sausalito News, Volume 66, Number 48, 6 December 1951. The Golden Gate Bridge, which was closed to traffic from 5:55 p.m. to 8:54 p.m. during last Saturday night’s gale was primarily a precautionary measure, according to the bridge's general manager. The bridge could have been reopened a half hour later, but remained closed to permit time for an inspection. Except for World War II blackouts, the shutdown marked the first in the 14-year
Resisting the Twisting Marker (<i>wide view; Golden Gate Bridge in background</i>) image. Click for full size.
By Cosmos Mariner, July 8, 2014
3. Resisting the Twisting Marker (wide view; Golden Gate Bridge in background)
history of the bridge. Traffic was reported to have lined up nine miles in Marin County and thousands of motorists were delayed on both sides of the bridge. (Submitted on March 18, 2019, by Cosmos Mariner of Cape Canaveral, Florida.) 

2. Golden Gate Bridge Deck Vibration, Stability, and Retrofit. Princeton University civil engineering professor Dr. Maria Garlock shows how this exhibit, designed by Elizabeth Deir, a student of hers, lets the visitor feel the difference in the torsional (twisting) stiffness of the original Bridge deck as compared to the deck after its wind engineering retrofit was implemented in the 1950s. (Submitted on March 18, 2019, by Cosmos Mariner of Cape Canaveral, Florida.) 
 
Categories. ArchitectureBridges & ViaductsMan-Made Features
 
More. Search the internet for Resisting the Twisting.
 
Credits. This page was last revised on March 18, 2019. This page originally submitted on March 17, 2019, by Cosmos Mariner of Cape Canaveral, Florida. This page has been viewed 41 times since then. Photos:   1, 2, 3. submitted on March 18, 2019, by Cosmos Mariner of Cape Canaveral, Florida.
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