CFRP
(Carbon Fibre Reinforced Polymer)-strengthening with plates and sheets of
existing concrete structures is
today a well-known method, proven with good
results all over the world. However, limited research has been carried out
regarding the behaviour of CFRP strengthen structures in cold climates. This
paper addresses field testing of a CFRP strengthening pre-stressed concrete
hollow box-girder bridge in Stockholm, Sweden, the Gröndals Bridge. Also how
the strengthening behaves in cold climate is investigated. Two long term
monitoring systems has been installed on a, one traditional system with LVDTs
(Linear Vertical Displacement Transducers) mounted over cracks for continuous
monitoring and one system with FOS (Fiber Optical Sensors) mounted over cracks
and on CFRPplates. Results show that difference in temperature causes most of
the live load. Other results from summer and winter measurements shows that the
CFRP plates are not tensioned during winter. A conclusion from this is that the
strengthening would have been much more effective if the CFRP would be applied
in the winter when the existing structure is contracted due to the temperature
effect. Furthermore, the opening of cracks could be followed over time.