what determines the distancea beam bridge can span
Beam bridge Beam bridges are often only used for relatively short distances because, unlike truss bridges, they have no built in supports. The only supports are provided by piers. The farther apart its supports, the weaker a beam bridge gets. As a result, beam bridges rarely span more than 250 feet (80Â m). This doesn't mean beam bridges aren't used to cross great distances, it only means that a series of beam bridges must be joined together, creating what's known as a continuous span.
Sundial Bridge at Turtle Bay The Sundial Bridge is a cantilever spar cable-stayed bridge, similar to Calatrava's earlier design of the Puente del Alamillo in Seville, Spain (1992). This type of bridge does not balance the forces by using a symmetrical arrangement of cable forces on each side of its support tower; instead, it uses a cantilever tower, set at a 42-degree angle[9] and loaded by cable stays on only one side. This design requires that the spar resist bending and torsional forces and that its foundation resists overturning. While this leads to a less structurally efficient structure, the architectural statement is dramatic. The bridge is 700 feet (210Â m) in length and crosses the river without touching the water, a design criterion that helps protect the salmon spawning grounds beneath the bridge.[10] The cable stays are not centered on the walkway but instead divide the bridge into a major and minor path.