TDOT Stabilizes I-24 Hillside After Landslide

VSL Picked to Install Post-Tensioning for Huey Long Bridge

Fri March 30, 2007 - Southeast Edition
CEG



VStructural LLC (VSL) has been selected to furnish and install a bonded post-tensioning system for the $660-million Huey P. Long Bridge widening project in Jefferson Parish, La.

The Huey P. Long Bridge has served the New Orleans area since 1935. This widening project will add an additional travel lane and inside and outside shoulders to each side of the bridge — providing a safer, more reliable Mississippi River crossing. The completed project will include three 11-ft. (3.3 m) lanes in each direction, along with new inside and outside shoulders across the bridge. The project also will include construction of new roadway approaches that will provide signalized intersections at Bridge City Avenue and Jefferson Highway. This four-phase project has been greatly anticipated by local communities and is thought to be vital to the recovery of the Greater New Orleans area.

General contractor Massman Construction Co. hired VSL to supply the post-tensioning materials, equipment and installation. VSL’s responsibility includes supply and installation of 111 tons (100 t) of 0.6-in. (1.5 cm) diameter post-tensioned strand for the retrofit of the piers used to widen the existing bridge. According to Jeff Lungrin, VSL project manager, post-tensioning — a method of reinforcing and prestressing concrete, masonry and other structural elements — was selected for this project because the method easily accommodates the challenge of widening the existing piers.

“Post-tensioning is a very effective method of providing circumferential reinforcement for the existing piers,” said Lungrin. “In addition, horizontal post-tensioned tendons will be used as reinforcement at the ends of the piers where the thickness of the concrete will increase.”

Gregory Hunsicker, the VSL sales engineer for this project, also said the project involves the use of VSL’s intermediate Type Z-anchor, which is useful for both circumferential and repair applications.

Intermediate anchorages are used for those tendons where the ends cannot be anchored using normal stressing anchorages.

“The use of Z-anchors eliminates the need for stressing buttresses. As a result, the concrete forming is simplified and the aesthetics of the structure improved,” said Hunsicker.

Further, because of its high strength (270 ksi) and flexibility around the radii of the corner of the piers, the prestressing steel also lends itself to an efficient, durable and aesthetically attractive design. Another feature of the anchor head is that the anchor moves along the tendon axis during the stressing operation within a block-out. Following the completion of the post-tensioning, the block-out is later filled with a concrete pour-back.

With bonded post-tensioning, the prestressing steel is placed in a corrugated metal or plastic duct that has been cast into the concrete — typically after the concrete has been placed. A bonded post-tensioned tendon usually contains more than one prestressing steel strand and can range from several strands to 55 or more in a single tendon. The strands can be stressed individually or simultaneously with a monostrand or multistrand hydraulic jack. For Z-anchors, a curved jack chair is used to provide access for stressing.

After stressing, the duct is filled with a low-shrinkage, zero-bleed flowable cementitious grout to achieve bond to the concrete member and to protect the prestressing steel from corrosion.

VSL’s services are scheduled to begin in April and be complete by the end of this year. The first phase of the project began in April 2006 and the entire project will be complete in 2012.

The Huey P. Long Bridge Widening Project is one of three major bridge projects included in the TIMED Program — the single largest transportation program in state history. VSL also is providing its SSI 2000 stay cable system for the John James Audubon Bridge, which is part of the TIMED program.

For more information, visit www.hueypbridge.com.