Construction—EMEA—Netherlands—Structural Repair Solutions
DYWIDAG Bar Tendons enhance Load-Bearing Capacity of the A44
Approach Bridges near Leiden
The bridge accommodating the A44 Motorway near the city of Leiden northeast of The Hague is more than 50 years old. Here, two
parallel steel bascule bridges with reinforced concrete approach bridges crosses the Old Rhine River. Due to a significant increase
in traffic volume on this section within the last decades, the Rijkswaterstaat decided to replace the entire asphalt wearing surface,
to replace the steel bascule bridges and to strengthen some sections of the approach bridges.
The superstructure of the approach bridges
consists of 1.1m high, T-shaped precast
post-tensioned concrete girders. The total
deck width is approximately 20.2m. On the
north side, there are 5 approximately 22m
long spans with 2 x 8 girders per span.
On the south side, there are 4 approximately
20m long spans with 2 x 6 girders per span.
A 20cm thick top slab was cast in place
partly between the 15cm thick upper
flanges of the girders and partly above them.
Furthermore, four transverse beams were
cast in place to provide sufficient structural
integration of the girders.
In various precast concrete girders,
diagonal cracking and local corrosion
of the post-tensioning anchorages was
detected. Furthermore, some girders
had been exposed to a fire in the past.
After comprehensive investigations into
the structure and calculations which were
carried out with reduced pre-stressing
forces, it was determined that the shear
capacity of several girders was insufficient
to meet current requirements.
Therefore, a strengthening solution using
so-called “post-tensioning stirrups” was
proposed by the consulting engineers.
DSI Construction Netherlands produced,
supplied, installed and tensioned a total of
439 of those special post-tensioning stirrups
that were used near the supports of the
21 girders with reduced bearing capacity.
Each post-tensioning stirrup consisted
of 2 vertical DYWIDAG Bar Tendons that
were installed vertically along the girders.
A total of 878 Type 32 WS, Y 1050 H
DYWIDAG Bar Tendons were used.
At the upper side of the girders, a massive
anchor plate with two welded couplers was
used as a dead-end anchor. At the lower
side, a steel beam was used as support
for two separate stressing anchors.
At each post-tensioning stirrup, two
DYWIDAG Bar Tendons were stressed
simultaneously with a force of 365kN
per tendon.
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After stressing, the PE sheathing of the
tendons was grouted and protection
caps were applied in order to obtain
adequate corrosion protection for the
DYWIDAG Tendons.
Work on this complex and challenging
project was carried out within a very tight
schedule in order to limit traffic obstructions
to a minimum. DSI is proud to have
contributed to the successful completion
of this project.
Owner
Rijkswaterstaat
(Department of the Dutch
Ministry of Infrastructure and
Environment), Netherlands
General Contractor
Joint Venture, consisting of
BSB Staalbouw B.V. and Mourik
Infra, both Netherlands
Consulting Engineers
Movares Nederland B.V.,
Netherlands
Subcontractor Post-Tensioning
DYWIDAG-Systems International B.V.,
Netherlands
DSI Scope
Production, supply, installation,
post-tensioning
DYWIDAG Products
878 Type 32 WS DYWIDAG Bar Tendons