Bridge deck link system - Post-tension - Bridge deck link system

The Algabar prestressing bars are part of a building system that creates a flexible connection between the decks, providing a hinge connection in the area between adjacent decks. This solution maximizes the benefits of continuous structures (linking the deck in the longitudinal and transverse direction and thus reducing the number of expansion joints) without deleting the simple construction concept of the simply supported beams isostatic structures (simplicity of design and construction).

The system is suitable for new buildings or even for retrofitting of existing structures, is very easy to design and install and allows to concentrate all the deformations of the viaduct in well-defined points, which can be the viaduct longitudinal axis or the abutements.

The devices consist of a series of high-strength steel bars 5400 mm long, with anchor plates at the ends with their nuts and a rubber strip placed between two steel profiles embedded in the slag edges (see joint type "Alga SP"). The compressive forces are released entirely on the rubber profile through the two angular steel profiles to the slab, while the tensile forces and the post-tension strength are absorbed directly by the bars and the slabs through the anchors.

The section of the bar between the anchors is covered with corrugated duct, filled with protective material and further protected in the area of the passage between the slabs by a second smooth duct. This duct is designed to allow relative movements of the decks, without inducing bending stresses in the bar beyond the allowed limits.

The installation procedure is very simple:

Before casting the slab, at the same time of the reinforcement laying, put the link bars towards the gap between the deck slabs. Post-tension force, distance and position in plan and transverse direction of the bars are generally defined by the bridge designer.

Install the steel profiles for the expansion joints that anchor the link system to the structure.

After concrete aging and after having prepared a hollow box for the bar stressing, insert the joint "Alga SP" in steel profiles and stress the bars, after having released the bearings temporarily fixed.

The mortar casting in the hollow boxes completes the simple installation procedure.