Span (engineering)

In engineering, span is the distance between two adjacent structural supports (e.g., two piers) of a structural member (e.g., a beam).

The first kind is used for bridges, the second one for power lines, overhead telecommunication lines, some type of antennas or for aerial tramways.

[citation needed] Span is a significant factor in finding the strength and size of a beam as it determines the maximum bending moment and deflection.

in the pictured beam is found using:[2] where The maximum bending moment and deflection occur midway between the two supports.

From this it follows that if the span is doubled, the maximum moment (and with it the stress) will quadruple, and deflection will increase by a factor of sixteen.