Presidio of San Francisco in San Francisco City and County, California — The American West (Pacific Coastal)
Resisting the Twisting
Photographed By Cosmos Mariner, July 8, 2014
1. Resisting the Twisting Marker
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.
Topics. This historical marker is listed in these topic lists: Architecture • Bridges & Viaducts. A significant historical date for this entry is December 1, 1951.
Location. 37° 48.488′ N, 122° 28.441′ W. Marker
this page online
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); The Golden Gate Bridge (about 400 feet away, measured in a direct line); Men of Vision (about 400 feet away); Joseph Strauss Legacy Circle (about 400 feet away); Types of Bridges (about 500 feet away); Tall and Strong (about 500 feet away); Steel, Fog, Salt, Rust, and Paint (about 500 feet away); Facts & Figures About the Bridge (about 500 feet away). Touch for a list and map of all markers in San Francisco.
Also see . . .
1. Bay Area Storm Hits City GOLDEN GATE BRIDGE CAN "TAKE IT". California Digital Newspaper Collection website entry:
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 history of the bridge. Traffic
Courtesy Golden Gate Bridge, Highway and Transportation District
2. Marker detail: The new bracing is visible in the bottom level
2. Golden Gate Bridge Deck Vibration, Stability, and Retrofit. Welcome to the Golden Gate Bridge History and Engineering Exhibition website entry:
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.)
Photographed By Cosmos Mariner, July 8, 2014
3. Resisting the Twisting Marker (wide view; Golden Gate Bridge in background)
Credits. This page was last revised on February 7, 2023. It was originally submitted on March 17, 2019, by Cosmos Mariner of Cape Canaveral, Florida. This page has been viewed 285 times since then and 31 times this year. Photos: 1, 2, 3. submitted on March 18, 2019, by Cosmos Mariner of Cape Canaveral, Florida.
