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Modeling concepts for bonded anchors

The efficient and permanently safe design of fastening systems requires a thorough understanding of all involved load carrying mechanisms and their potential change in course of time due to deterioration and material ageing. The latter are determined by the involved materials - concrete, steel, and, depending on the system, the mortars. In this contribution we focus on the behavior of bonded anchors under predominant tension loading.
Traditionally, cast-in steel bars as well as bonded anchors are modeled as 1D beam elements with perfect connection to the base material (e.g. concrete) or formulations in terms stress-slip laws. The current design practice for fastening elements utilizes the so-called uniform-bond model for practical reasons.
In this contribution we will compare different modeling techniques for bonded anchor systems in concrete. All model formulations will be calibrated and validated using a consistent experimental dataset supplemented by surface strain measurements that are obtained by 3D DIC. Concrete will be described by a well-established discrete particle model, which will be compared to traditional damage plasticity models. Levels of discretization for the anchor include 1D beam elements as well as 3D solids. Models for the mortar layer include standard stress-slip laws as well as surrogate models that are derived from lower scale models. All modeling approaches are compared with regard to their ability to capture the correct failure mode, the prediction quality in terms of load-displacement curves, and the computational cost. A model parameter sensitivity analysis completes the study.

Author(s):

Marco Marcon    
CD Lab, IKI, BOKU Vienna
Austria

Jan Vorel    
CD Lab, IKI, BOKU Vienna
Austria

Roman Wendner    
CD Lab, IKI, BOKU Vienna
Austria