pin and weld

A pin and hanger assembly is used to connect two plate girders of a bridge. These assemblies are used to provide an expansion joint in the bridge. One beam (the anchor span) is set on a pier with a short section cantilevered out toward the next pier. The other (the suspended span) begins underneath the anchor span, and has its far end resting on the next pier. The beams have holes directly above each other. The two holes are connected using hangers, a pair of connecting plates sandwiching the bridge girders. A pair of large steel pins through the plates and girder webbing provide the hinges, holding up the suspended span while allowing it to move longitudinally. Large washers are bolted to each end of the pin to retain the hangers. Exceptionally long spans may have two sets of girders cantilevered from opposite bridge piers with a third set of girders suspended by pin and hanger assemblies from both cantilevers.

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