Abstract
In Europe, the qualification of injection anchors in masonry under static and quasi-static actions is based on an assessment of tests performed in undamaged masonry. Nevertheless, in seismic prone countries like Italy the influences deriving from earthquake actions cannot be disregarded. Masonry elements are very sensitive to cyclic/seismic action and research on the behavior of anchors in damaged masonry is rather limited. The paper presents the results of an experimental campaign aimed at evaluating the residual tensile strength of adhesive anchors installed into undamaged walls that were subsequently subjected to cyclic in-plane loading to simulate seismic actions before. Consequently, the anchors experienced different stresses depending on their location within the walls. Overall, 29 tests were performed with anchors placed both, in undamaged and damaged areas. The results showed that there is a correlation between residual tensile strength and masonry initial conditions, and therefore the installation of anchors in masonry elements should be carefully planned avoiding areas that could be heavily damaged during seismic events or considering redundant connections in critical areas. In particular, it seems that the width of the crack (created by cyclic actions) that passes nearby/into the anchor borehole is the main parameter that affects the ultimate resistance of the anchors.
Highlights
It is well-known that masonry structures are highly vulnerable to seismic actions, since they have great mass, low tensile strength, and ductility
The results show that the anchors along the diagonal (A3, A4, A6) feature the lowest carrying capacity with failure associated to anchor pull-out and/or brick failure or cone failure
There seems to be a clear correlation between the crack width, measured on the surface at or nearby the anchor location, and its maximum recorded load capacity
Summary
It is well-known that masonry structures are highly vulnerable to seismic actions, since they have great mass, low tensile strength, and ductility. ). Basic investigations under quasi-static loading are reported in [18,19,20], but due to the complexity of masonry injection anchor performance assessment is still mainly based on experimental testing [13] and only few predictive equations are used in design [14]. Many efforts have been made to evaluate the behavior of postinstalled anchors in concrete [21,22,23,24,25,26,27,28,29,30] under different conditions (i.e., concrete strength, cracked/non cracked), leading to a well-defined standard framework that allows designers to rely on equations or testing procedures that consider the determination of the performance of a fastener even under critical conditions such as seismic action.
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