Evaluation
of the aerodynamic loads on long-span bridge deck
Actual bridge decks are always equipped
with various platform equipments, such as traffic, wind or noise barriers,
carter or aerodynamic appendages. The scaled models that are experimentally
used generally violate the aerodynamic similitude conditions of these elements.
On the other hand – because of the appearance of aerodynamic interference
phenomena in the separated flow around a bridge deck – the aerodynamic and
aeroelastic behaviour of the deck often shows characteristics of marked
sensitivity to these disturbing elements. The computational studies proposed on some of the most important actual
long-span bridges confirm the remarkable influence of these elements on both
the intensity of the static wind loads and on the frequency content of the
dynamic excitation. The knowledge of the physical phenomena at the basis of
these variations allows, as proposed in, aerodynamic devices or semi-active
control systems to be designed in order to increase the aerodynamic performance
(reduction of the aerodynamic forces, suppression of the vortex shedding,
increase of the aeroelastic damping) of existing bridges and to allow longer
span bridges to be built.
