Lightly reinforced concrete walls in formwork blocks for the combined seismic and energy retrofit of masonry structures

In recent years the interest is arising towards systems for the combined structural and energy retrofit of existing structures. In the present paper a retrofit system consisting in a lightly reinforced concrete wall realized within formwork blocks in expanded clay is proposed; the shape of the blocks allows the introduction of an insulation layer with high isolation capacity. The system is conceived to work in parallel with the existing masonry structure: the realized reinforced concrete wall acts as a shear panel devoted to carry on the horizontal seismic actions, being the existing masonry walls in still in force to sustain vertical loads. Opportune connections are realized in correspondence of the horizontal floors' levels to transfer only the horizontal actions. Conceptual design, together with application to a real case study existing masonry building that allows to size and detail the panel, is presented. The results of experimental tests with horizontal forces on the proposed system are shown, as well as the calibration of a simple model able to estimate its dissipative performance as function of structural details and material properties.