A
large number of concrete bridges built in Europe were characterized by
Reinforced Concrete (RC) hollow piers;
many of them are now in need of a
seismic upgrade to improve their response under severe earthquakes. Researchers
have mainly focused their attention on solid piers; few studies have been done
about hollow cross sections. To study the behaviour of rectangular hollow piers
subjected to combined axial load and bending, a total of 7 specimens have been
tested. The strengthening was performed by Carbon Fiber Reinforced Polymers
(FRP) wrapping. Planned tests have allowed to improve the knowledge of
unstrengthened hollow rectangular piers and to provide a contribution towards
the comprehension of the resistant mechanisms of hollow piers in presence of
FRP confinement. The experimental results and the related database has been
used for validation of CFRP strengthening design methods for hollow cross
sections and for assessment of potential extension of the current models
available for solid sections to non-circular hollow sections. Strengthened and
unstrengthened members have been numerically modelled. The results of the
present work suggest that a reliable numerical procedure to predict hollow
cross section behaviour under combination of flexure and compression should
include appropriate models for compressed bars buckling and concrete cover
spalling.