Suspension bridge load paths

Trace how a bridge deck, hangers and main cable share gravity loads as the structure settles.

How do cables carry a bridge’s weight?

Monochrome sketch of the John A. Roebling Suspension Bridge showing its deck, main cables and vertical hangers at a stone tower
Reference sketch: the deck, tower and cable system of the John A. Roebling Suspension Bridge, adapted from a photograph.
Sketch from photo: Nathaniel Mitchell · Public domain · sketch adaptation

What you can model

Four connected steel box beams form a continuous deck beneath a segmented main cable. Three vertical hangers transfer load between them, with fixed elevated cable anchorages at the ends. The geometry diagram makes the load path visible before the response plots show the assembly settling under gravity.

Continuous beam deck, main cable, three hangers and end supports.
Continuous beam deck, main cable, three hangers and end supports.

What you can explore

Follow deck displacement and cable tension as the motion approaches equilibrium. Then compare the combined left-end reaction with half the total weight. That reaction includes both the cable anchorage and deck support, showing how their contributions work together to carry the bridge.

Deck settling, cable tension and combined left-end reaction.
Deck settling, cable tension and combined left-end reaction.

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