Mechanical behaviour of adhesive anchors installed in concrete
The thesis presents the main characteristics of the mechanical behaviour of adhesive anchors installed in concrete. They are the mechanisms of failure, the relationship between applied pull-out load and slip of the anchor and the stresses and strains in each of the three components (steel-resin-concrete). The study is primarily experimental but theoretical and finite element analyses are also included. These main characteristics are dependent on the adhesion and wetting phenomena across the resin-concrete and resin-steel interfaces, and on a series of parameters relating to geometry, properties of materials and methods of installation. The principal conclusions obtained are: a) The combined mode of failure involving concrete, resin tensile and interfacial bond failure, is the most probable provided that the resin has a high adhesive strength and that the anchor diameter is larger than the minimum value necessary to prevent steel failure, which can be calculated. b) The sequence of failure in the combined mode is concrete failure in the upper part, bond failure in the remaining part of the anchor, and resin tensile fracture at the bottom of the anchor. c) The values of pull-out load normalized with respect to concrete strength can be regarded as independent of concrete strength. Therefore, a limit state design criterion for adhesive anchors in any concrete substrate can be established. d) The values of anchor displacement normalized with respect to concrete strength vary linearly with it. Based upon this, a simple mathematical function can be determined, which allows the calculation of the displacement of any adhesive anchor. This can be used as a design criterion for the limit state of serviceability of the particular system.