Influences on the bond behaviour of anchorages under short-term and long-term loading

Abstract

This thesis focuses on the load-bearing behaviour of adhesive anchors. The influences on the bond strength of the anchors under short-term and long-term loading are investigated. The first part describes the current state of the art of bonded anchors under tensile loading and the influences on the load bearing capacity under short-term loading. In the second part, the factors influencing the long-term loading of adhesive anchors are presented. This section is a summary of various external and internal research. The influence of different parameters on the bond behaviour under long-term loading is then discussed. The third part focuses on the influence of incremental loading on the bond behaviour of adhesive anchors. The tests were part of a research project at the Institute of Construction Materials of the University of Stuttgart. As reference tests served short-term tests where the maximum load was reached within 3 minutes. To achieve incremental loading, the anchors were loaded at five percent steps. After loading, the anchors were unloaded and then reloaded within five minutes. Different parameters are varied throughout the test program: the embedment depth, the support width, concrete condition, drilling diameter, hole cleaning and the temperature while testing. Lastly, the short-term influence on the bond behaviour is investigated. High-strength concrete is used as anchorage base material to test epoxy adhesive anchors. This section describes this behaviour concerning the embedment depth, the bond length of the anchor, the type of steel component and the support width. A comparison between the failure load and the predicted load using the design models from the literature is carried out. Based on the results of the previous parts, the most critical influences on the bond behaviour of adhesive anchors are presented in the last section.