CD Laboratory for Life-Cycle Robustness in Fastening Technology

The topic is fastening systems (anchors) and their long-term behaviour in concrete: physical, mechanical and chemical influences and their effects are systematically recorded. The aim is to develop experimentally verified prediction models for ageing and degradation and to quantify the prediction quality.

Life cycle robustness refers to the ability of a fastening system to fulfil its position over its entire service life - despite ageing and damage processes and while maintaining the required level of safety.

To this end, this CD Laboratory relies on an interplay of experiment and simulation: the decisive mechanical, physical and chemical factors influencing life cycle robustness are systematically determined by means of specially developed experimental investigations, on the basis of which methods for computer modelling can then be developed.

The experimental part of this laboratory deals with the precise analysis of the individual components of common fastening systems (concrete, adhesive, dowels), their mutual interaction and the change in characteristics with influences such as ageing, chloride ingress or weathering. This requires a comprehensively equipped experimental laboratory, which includes a 3-axis servo-hydraulic testing machine, standard testing machines for material characterisation, a climate chamber, a test chamber for destructive tests under changed temperature conditions and non-contact imaging and traditional measuring systems.

The results of the experimental observations form the basis for the calibration and validation of numerical simulations, which in turn serve to design more detailed experiments. The aim is to develop the basis for the numerical simulation of the service life of fastening systems, which can also take into account rare combinations of environmental effects, load combinations and material properties. A typical example would be the determination of the load-bearing capacity and remaining service life of a façade fastening corroded by many years of chloride exposure and exposed to a storm of a century. For this purpose, the uncertainty in all input values must be described using scatter bands and distribution functions, their static dependency characterised and the probability of occurrence of different scenarios recorded.

This allows the interaction between the anchor and concrete (structural response) to be precisely predicted - from the time of installation to the end of the service life. Not only can new fastening systems be developed on this basis, but the safety of fastening systems in existing buildings can also be assessed.