Injected Anchors For The Seismic Retrofit Of Historical Stone Masonry Buildings: In Situ Experimental Tests

The paper reports the results of a research on the behaviour of injected anchors in historical masonry under cyclic loads. Monotonic and cyclic pull-out in situ tests were conducted on historical stone masonry to analyse the response of anchors injected orthogonally to the masonry main plane and at different heights to evaluate also the effect of different values of normal confinement on the anchor behaviour. Moreover the tests were conducted on anchors of different length, instrumented with strain-gauges. The aim was to investigate the loss of strength under cyclic loads. The results allowed: 1) construction of load-displacement graphs, up to the maximum load value (maximum strength); 2) steel bar deformation graphs on the length of the anchors at different values of load, under cyclic loads; 3) qualitative bond stress curve, derived from the steel bar strains, to investigate bond behavior along the bar length.