Thermal behaviour of composite box-girder bridges

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.