International Symposium on High P
Topic : "UHPC Session"
wide case studies
EALIZATION OF THE FI
RST ROAD BRIDGES MAD
Z. HAJAR, A. SIMON
Eiffage Construction ; D. LECOINTRE, J. PETITJEAN
( Presenter : J. PETITJEAN
will attend and pre
sent if paper is chosen )
The two bridges described in this paper were built during the year 2001 under an "innovation
charter" set up for engineering structures ; they represent a world first for road bridges.
These two overpasses have each tw
o spans of 22,00 m and 20,50 m. The deck cross section is
12 m wide ; each is an assembly of five
shaped precast beams made of UHPC. The beams
are longitudinally pretensioned with bonded strands and their longitudinal and transverse
keying is made on sit
e with the same concrete cast in place.
The UHPC used has a compressive strength in excess of 170 MPa and a direct tensile strength
of 8 MPa with a 3 % of volume fiber incorporation. The steel fibers mean the concrete is not
except in keying area
and replace the reinforcing steel, especially for transverse
bending behaviour where only the UHPC takes part.
Special characterization methods of UHPC properties have been also carried out in order to
get pertinent design data : flexural tests includi
ng fatigue on deck slab elements, tests on
prisms taken from a real
size beam element to estimate fibers distribution in the structure and
also creep evaluation made by deflections monitoring during precasting.
This application also required to settle spec
ial calculation methods and design rules which are
not currently covered by codes for the type of concrete employed. These rules where finalized
in close collaboration with recommendations of a working group on UHPCs.