This paper investigates the behaviour of composite box-girder bridges subje
ct to environmental thermal effects such as solar radiation, air temperatur
e and mind speed. It is based on the statistical analysis of measured tempe
rature data which were recorded hourly in a newly constructed composite box
-girder bridge for about 20 months continuously. Major thermal loading para
meters that characterize the temperature profile are defined, and the seaso
nal behaviour of the parameters is described in detail. The experimental re
sults are compared to the specifications suggested in the design codes for
thermal loads. In addition, a series of heat transfer analyses using the tw
o-dimensional finite element method is conducted in order to generalize the
results to bridges with different cross-sections. The findings of this stu
dy show that the design temperature distribution with uniform differential
between the concrete slab and the steel girder is unsuitable for representi
ng the thermal effects in design purpose.