Development of a Lamella-Model for the Assessment of Stresses during Hot Asphalt Installation

On road bridges, hot asphalt is installed to provide a protective, level and waterproof surface. That wearing surface however must be occasionally renewed after years of traffic loads. On a number of steel highway bridges, it has been observed that fatigue cracks increasingly occurred at the weld seams of orthotropic bridge-decks after such asphalt renewal. 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 induced by the installed layer of hot asphalt. Since FEM-software even on modern computer systems could not provide solutions for long, large-span bridges due to the required level of detailing, a software-based lamella-model was developed that saves time and computing resources. The lamella-model allows the partition of the bridge into rectangular beam-lamella, which consider precisely the nonlinear temperature profile and provide the determination of the inner forces, stresses, strains and displacements over the cross-section and along the bridge. This paper presents the theoretical background of the lamella-program as well as results calculated exemplarily for a 742-meter-long German highway bridge including the validation with temperature and strain measurements from that bridge during asphalting.