Advanced hysteresis method for early damage detection of fastening systems in concrete under fatigue load

This paper presents an advanced method for the characterization of the fatigue failure and corresponding load process of fastening systems in concrete. The required hysteresis model is based on mathematical and physical principals with a secondary approximation of the hysteresis loops using measurement data in accordance with conformance criteria. Thus conventional characteristic values of the hysteresis loop, displacements, stiffness's and energies could be determined. The developed predictive model uses four adjustment parameters (determined through regression analysis) and was applied to experimental fatigue tests of anchor channels in concrete. Investigations of these adjustment parameters revealed the potential to identify an indicator for the early prediction of experimental tests, in relation to specific changes and processes in the shape and area of hysteresis loops. These geometric properties effect modifications of the hysteresis centroid - being a sensitive characteristic of the loop form, is determined through numerical methods and analysed in correlation with the four adjustment parameters.