Innovative Widening Truss Erection of the Huey P. Long Bridge

摘要

The Huey P. Long Bridge crosses the Mississippi River in New Orleans, Louisiana. The bridge opened to traffic in 1935; it is an 1840-foot three-span continuous cantilever truss bridge with an adjacent 530-foot simple span through truss which carries rail and v ehicular traffic. Th e p roposed wid ening o f the b ridge will b e co mplete b y 201 3. Th is p aper will add ress th e erection of the main river unit widening trusses as well as focus on the analysis and behavior of the temporary stability frame used to the brace the trusses during the lifts. The Mississippi River, at the location of the Huey P. Long Bridge, is a heavily traveled shipping channel This feature of the river drove the primary goal to minimize the risk of ship impact to falsework in the river. This gave rise to an innovative method to erect the primary trusses span by span eliminating the need for falsework in the river. The span by span erection method, utilizes temporary stabilizing frames that span between the bottom chords of the proposed widening trusses and have stabilizing towers to brace the compression chord of the truss while lifting. The whole system of trusses and stabilizing frames is lifted at the four corners by strand jacks supported on the top of the widened pier trusses. During the lift, the trusses are positioned outside of the pier trusses to allow them to be lifted to their final height. Once the trusses are lifted 150 vertical feet, the stabilizing frames telescope inward and pull the widening trusses transversely and are then lowered slightly onto their permanent bearings.