TYING IT ALL Together

摘要

The Rancocas Creek Bridge, in Riverside, New Jersey, is considered the signature bridge for the new River LINE, a 34 mi (55 km) long light-rail system in New Jersey that will operate along the Delaware River between Trenton and Camden. Designed for joint light-rail and Cooper E80 freight train loading, it may also be the first steel tied arch to carry freight trains in the United States. A tied arch consists of an arched rib girder connected longitudinally at its ends by a tension element, or tie girder. The tie girder balances the horizontal thrust from the arch. This arrangement distinguishes a tied arch from a true arch, which relies on large abutments. The tie girder is supported by the rib girder through hangers. When the .bridge deck is loaded, forces are transferred from the deck and stringers to the floor beams, from the floor beams to the tie girder and hangers, and from the hangers to the rib girder. The rib girder carries the load in compression. Bending is also present when the load is unsymmetrical. The compression in the rib is carried to the ends, where the vertical component is resisted by bearings and the horiz tal component is resisted by the tie girder.