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 ShapeThis 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 ShapeThis 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.