Experimental study on injected anchors for the seismic retrofit of historical masonry buildings

The paper reports the results of a research on the behaviour of injected anchors in historical masonry under cyclic loads. Laboratory tests with masonry specimens (bricks and mortar with low characteristics to replicate real historical masonry) were conducted to analyse the response of steel anchors injected using a special sock and with different types of mortar (cement and lime based). The test benches replicate the real condition of the use of these anchors: they allow to simulate the connection of masonry panels (T and L connections) or the anchor of steel ties to contrast the arch thrust. Monotonic and cyclic pull out tests were conducted on short and long anchors to define the loss of strength under cyclic loads for different situations. The results allowed to obtain: load-displacement graphs; steel bar deformation graphs on anchors’ length; a qualitative bond stress curve; comparison among maximum strengths obtained under several conditions.