Masonry panels with external thermal insulation subjected to in-plane diagonal compression

Partial collapse of masonry facades during past strong earthquakes is well documented together with the increased vulnerability due to the presence of thermo-insulation within double wythe masonry. The combined seismic and energy retrofit of existing aged buildings represents a topic of importance for the building stock. The current study investigates the in-plane performance of a specific thermo-insulation scheme with panels attached on the external facades of multistory buildings. Diagonal compression tests of prototype specimens are done to study the influence of thermal insulation on the in-plane behaviour of clay brick masonry panels with or without thermal insulation. It was found that the thermo insulating attachment of the tested type performs in a satisfactory way when subjected to the stress field that arises to these masonry panels when subjected to diagonal compression. The thermo insolating panels, although finally debonded from the masonry substrate, do not collapse, even when the masonry panel develops large diagonal cracks, due to the presence of the used plastic anchors. The presence of such thermo insulating attachments leads to an increase of the in-plane load capacity and to a less brittle behaviour than the one without this thermo-insulation. This may also lead to a less vulnerable seismic performance than that of the same masonry panel without this thermo insulating attachment, although further validation is needed considering also the out-of-plane performance. The employed numerical modeling was successful in simulating the most important aspects of the in-plane response of the tested masonry wallets with or without thermo-insulating attachments. The good agreement with observed performance as well as the general nature of this numerical simulation confirms its validity.