Depending on project requirements, DSI employs two different stressing methods.

1. Stressing with multistrand jacks

This procedure can be used for cables with DYNA Bond ^® Anchorages.

All strands in a cable are stressed simultaneously with one hydraulic jack attached to the anchorage. Jacks up to a capacity of 15,000 kN are available. The advantage of this method is the fast and accurate stressing operation of the cable in one step. However, it is important to provide sufficient working space at the anchorage and to be aware of the fact that special lifting may be needed to handle the jacks efficiently.

2. Stressing with monojacks using the ConTen-System

This patented procedure is applicable for both DSI DYNA Bond ^® and DYNA Grip ^® stay cable systems.

All single strands are stressed immediately after being installed in the cable anchorages and thus optimising the entire installation process. A special calculation method has been developed by DSI to determine the force for the first strand and the corresponding forces for the subsequent strands in order to monitor the stressing operation up to the required final cable force.

A light weight monojack is placed on a stressed strand and an identical jack is placed on the strand to be stressed next. The jacks are hydraulically linked to compare the actual pressure in both jacks during stressing. This ConTen System makes it possible to equalize the force in all strands at the end of the stressing operation. In addition, the influence of temperature and load changes in the cables and in the structure during stressing are automatically eliminated.

After completion of the structure, it is possible to adjust the cable force by restressing or destressing the complete cable via the ring nut (shims are used in case of longer elongations). Special compact and lightweight gradient jacks are available for adjusting the cable force and the bridge profile, if necessary.

Tests

DYWIDAG Stay Cables have been successfully tested in static and fatique tests in compliance with PTI and/or fib recommendations. Also, tests with anchorages with an inclination of 0.6°as well as the leak tightness test - required by fib bulletin 30 - were successfully conducted.

DSI Services

• Comprehensive consulting services
• Special design and installation planning
• Component manufacture and delivery
• Installation: either turn-key using DSI staff, or project supervision and staff training
• Inspection and maintenance services