Enerpac strand jacks for Gerald Desmond Bridge Pier decks lift

13 November, 2018

Cable-stayed design

The bridge has a cable-stayed design based on two 157m steel reinforced concrete towers.

Due for completion in 2019, it will be the second-tallest cable-stayed bridge in the US and with the highest vertical clearance of any cable-stayed bridge in the US. Bigge Crane and Rigging’s task was to lift the pier tables for each of the two towers, which will form the east and west ends of the 610m main span extending over the water channel.

Bigge used Enerpac HSL 5000 strand jacks to lift the pier tables. “The Enerpac strand jack is perfect for this kind of job,” said John Levintini, projects operations manager at Bigge Crane and Rigging. “It would have been impractical to use a crane given the size and weight of the pier table. The strand jack is the best choice in terms of both lifting capacity and cost.”

 Four-column falsework

In preparation for the positioning on the pier tables, four-column falsework was installed on each of the two towers. Enerpac HSL 5000 strand jacks, each with 48 steel strands, were positioned at each corner of the falsework to lift the steel framework pier table positioned around the base of the tower. Synchronising the strand jacks allowed all lifting positions to be raised simultaneously, ensuring the pier tables remained balanced. Positioning the pier decks called for patience and precision; each stroke of the strand jack was 46cm, with the entire lift of each pier table taking 10 hours.

SCC control system

Bigge synchronised the lift through Enerpac’s SCC control system, allowing the entire lift to be managed by a single operator. “The lift was straightforward,” Levintini noted. “However, manoeuvring the pier table into its final resting position on the falsework was a delicate operation – the final alignment was co-ordinated with the strand jack and visual feedback by engineers on the piers.”

Mike Beres, sales director Americas, Enerpac Heavy lifting Technology, commented: “Strand jacks pack tremendous lifting capacity into a small footprint. Moreover, the system software can control up to 60 jack/pump combinations so the potential for large scale synchronous lifting is quite scalable. The flexibility of the strand jack system allows Bigge to use this equipment on many other projects across multiple industries.”

With the east and west towers’ pier tables in position, the first cable strands have now been installed. Each pier table is suspended by four cable strands running from the corners up to the first casing hole in the tower. Following the removal of the falsework, cranes will be lifted onto both pier tables to begin the balanced-cantilever construction of the main span.

 Joint effort

The Gerald Desmond Bridge Replacement Project is a joint effort of Caltrans and the Port of Long Beach, with funding contributions from the US Department of Transportation and the Los Angeles County Metropolitan Transportation Authority (Metro). Construction of the bridge is managed by SFI JV, a joint venture organisation comprising Shimmick Construction Inc., Spanish company FCC Construction, and Italian company Impregilo SpA.

www.enerpac.com