Sustained load and time to failure of fastening systems

Fastening systems play a crucial role in structural engineering, e.g. connection of structural elements, assemble precast elements, and attach non-load bearing components. The significance of fastening systems can be found due to the fact that the potential damage caused by failed fasteners could be quite higher than the value of the products themselves. Fastening systems are usually designed to serve for a long time horizon under constant loading. Thus, a safe design requires a thorough insight of all involved mechanisms, e.g. creep, shrinkage, and their potential change with time, for all in-volved materials. In case of sustained loading, it is necessary to define load level limits that do not lead to failure during service lifetime. Therefore, characterization of the viscoelastic properties, as well as of the loading rate strength dependency of all involved material is required. The aim of the present contribution is to characterize experimentally the viscoelastic and the time dependent fracture properties of fastening systems. Consequently, sustained load tests for different fastening systems, mechanical and chemical adhesive, loaded at different load levels, are tested. In parallel full material characterization, as well as characterization of the viscoelastic properties and of the loading rate dependency of the involved materials is carried out. In particular, various tests, including standard cylinder and cube compression, three point bending, and Brazilian splitting are performed. Addition-ally, the loading rate strength dependency is characterized through three point bending tests per-formed at different loading rates, while the fracture time dependency is characterized through three point bending time to failure tests