Seismic performance of infilled RC frames retrofitted with thermal insulation coatings

In recent years, the European Commission member countries has adopted measures and strategies to reduce energy consumption and CO2 emissions to contrast the effects of climate change. Considering that buildings are responsible for 40% of energy demand and 39% of CO2 emissions at global level, urgent measures are needed to improve their performances. In this context, improving the thermal performance of the buildings envelope has been demonstrated to play a key role in the overall building performance and, to date, many technical solutions are available on the market. However, only few studies have investigated the contribution of such system in the lateral response of full-scale infilled multistorey reinforced concrete (RC) buildings under earthquake loads. To fill this gap, an experimental program was carried out on a full-scale two-storey infilled reinforced concrete (RC) frame unretrofitted and retrofitted with thermal insulation coating applied from the exterior of the building with two different installation methods. The seismic displacements were applied by means of pseudo-dynamic testing method using the 2009 L'Aquila earthquake record scaled at different intensities. The results indicated that the use of a high-performance cementitious adhesive with a continuous application on the infill and the frame provides additional lateral strength. This allows to reduce the displacement demand at high earthquake intensities respect to the unretrofitted frame or the frame retrofitted by using a standard installation method. However, the increase of the base shear due to the increased infill strength lead to increase the shear demand on the ground floor columns, thus leading to potential shear failures. These aspects are discussed in detail based on the results of the tests and of a refined numerical model.