GOLDEN GATE BRIDGE
Behind the Golden Gate Bridge is a Structural Engineer
The Golden Gate Bridge is a well-known iconic bridge in the United States. Spanning California’s Golden Gate, this 1.2-mile suspension bridge was declared one of the Wonders of the Modern World when it debuted in 1937. What some people don’t know is that the structural engineering trio of Charles Ellis, Leon Moisseiff, and Joseph Strauss collaborated on the design of this iconic bridge in 1917. Spanning across the strait connecting San Francisco Bay and the Pacific Ocean, the structure utilizes suspension cables and a relatively flexible roadway to absorb the stresses caused by the heavy winds that blow through the “Golden Gate”.
Structural engineering excellence and leadership made the impossible possible. The Golden Gate Bridge was both the longest and tallest bridge in the world, with a main span of 4,200 feet and a total height of 746 feet. Its proximity to the San Andreas Fault places the bridge at risk of damage in a seismic event. The bridge underwent a seismic retrofit in 2001 that included the addition of seismic isolators and energy-absorbing devices on select portions of the structure.
Structural Engineering Innovation
The structural engineering trio collaborated to create an all-suspension bridge design, developing the proper calculations required for the design—a challenging task without computers. The main tools used included a slide rule and drafted plans they made on drawing boards using pencil and paper.
In 1933, a model tower was tested at Princeton University. The structural engineering trio’s calculations were verified by testing on a steel tower model that was 56 times smaller than the actual towers that would be developed. One test, with scaled-down force, simulated the actual 120 million pounds of vertical load that the main cables would place on top of each full-sized tower.
When construction began in 1933, construction safety was of critical importance. The Golden Gate Bridge’s Chief Structural Engineer, Joseph Strauss, innovated the use of movable safety netting beneath the construction site, which saved the lives of 19 men who were otherwise-unprotected ironworkers. Structural Engineers bring innovation and safety to every project.
Project Details
Construction Date: January 1933 to May 1937
San Francisco City Engineer Projected Cost: $100 Million
($2.4 Billion today)
Project Budget: $35 Million ($840 Million today)
Total Length: 8,981 from abutment to abutment
Towers and Cables: 2 main towers and 2 main cables
Each Cable: 27,572 strands of wire
Length of Galvanized Steel Wire for 2 Main Cables: 80,000 miles
Each of Bridge’s Two Towers: Approximately 600,000 rivets
