Development of a lamella-model to evaluate stresses caused by hot asphalt installation

On road-bridges hot asphalt is installed to provide a level and waterproof surface. That wearing surface, however, needs occasional renewal. On a number of steel highway-bridges it has been observed that after such asphalt-renewal fatigue-cracks have increasingly occurred at the welds of orthotropic bridge-decks. The German Federal Highway Research Institute has assigned a research project to RWTH Aachen University to evaluate the response of steel-bridges to time- and location-dependent, nonlinear temperature profiles. Since FEM-software with the needed level of detailing could not provide solutions for long large-span bridges, a software-based lamella-model was developed. This model enables the partition of the bridge into rectangular beam-lamella, precisely considers the nonlinear temperature and calculates the inner forces and displacements along the bridge. This paper presents the theoretical background of the lamella-program as well as results calculated exemplary for a 742m-long German highway-bridge including validation with in situ temperature and strain measurements during asphalting.