Open in 1937, the Golden Gate bridge is an art deco icon to the city of San Francisco. Weighing nearly 900,000 tons with a main span of 4,200′, it is an extraordinary example of a steel suspension bridge. The elements that create the structural integrity of the bridge are also the elements that define its rhythm of design.
The components of the design together create the intricate phenomenon that exists for a bridge of this scale. From south to north, the bridge is comprised of deck plate girder spans, Warren deck truss spans, a braced ribbed deck arch span, three suspended spans, and finally, more Warren deck truss spans. Each of these elements contributes a level of strength which works in a partnership with the others.
A truss is a structure made up of many smaller parts, which is used in the same way as a beam but can be made longer and deeper because of its assembly. The Warren truss is a specific type of truss, patented in 1848 by James Warren and Willoughby Monzoni of Great Britan. This type of truss is recognized by its composition of equilateral or isosceles triangles that connect the top and bottom chords. A deck truss is a truss in which traffic travels on top of the structure.
The engineering of the bridge serves structural purpose, but equally defines the organizational properties of the design. The triangular geometry articulated within the truss continues the length of the span, a unifying element of the rhythmic sort that accentuates the hierarchical nature of the composition. The vertical cables of the suspension spans also work as a repetitive element, ascending symmetrically and peaking at the two towers that emerge from the channel which connects the Pacific and the Bay.
The elements of the Golden Gate bridge illustrate a purity of form and its proportions create its dramatic presence, using the simplest possible design that safely realizes the bridge’s intent. A monumental and iconic feat, it is a defining landmark that displays architectural and engineering prowess, highlighting the landscape of San Francisco.