Safety Assessment of Tensile Elements and Anchored Structures

Pre-stressed anchors are indispensable elements in geotechnical engineering and represent a common technique for earth retention and slope stabilization. Tensile elements are widely used, aside from temporary use for building pit support, in the construction of road and railway lines. In addition to stabilize embankments and cuts, they are also used for retaining structures, abutments and pier footings as well as the reinforcement of existing structures. Anchored structures with permanent pre-stressed anchors must be observed by means of a periodic safety assessment, usually done by a visual inspection. Due to ageing, the increase in damage and the decrease of the conservation status, further examinations are increasingly required, usually in the form of anchor testing. The focus of such examinations is to determine the condition of the tendon and subsequently to assess the effects of damage on the structure's reliability.
The paper presents approaches for making more comprehensive and accurate statements about the condition of anchored structures and tensile elements and the influence of such on the bearing capacity of the structure. At the beginning, a workflow will be shown how a simple, yet conclusive and comprehensible estimation of the structure's reliability can be made, even if little information on the structure and the subsoil is available. Based on this, the possibilities of a numerical analysis of a defective structure, focussing on the failure of one or more anchors, will be shown. In addition, new approaches for the implementation of anchor lock-off testing and the monitoring of tensile elements are presented.

Keywords: Ensile element, Anchored structures, Inspection, Safety assessment, Testing.