A suspension cable under a uniform load hangs as a parabola, and the pull along it — its horizontal tension H — is the same at every point. It's the single number that decides how much the Golden Gate can take.
Real traffic crosses the span in 3D — every car's weight runs deck → suspender → main cable → tower. Overload it and the cables snap one by one, the deck tears, and the cars drop into the bay.
A suspension bridge is a load-relay.
No beam spans 1280 m. The deck hangs from vertical suspenders, which hang from two main cables in pure tension, leaning on the towers and pulling back on anchorages in rock.