Damage Control of Masonry Infills in Seismic Design

The present research report deals with the limitation of earthquake-induced damage to non-structural masonry infills in the design of RC structures, focusing on a specific group of infills widely adopted in European (and specifically Italian) construction practise. In particular, traditional clay masonry infill typologies with masonry panels constructed in complete contact with the surrounding RC frame are investigated. The principal objectives of the work are related to improvements in the understanding of the seismic response of newly designed masonry infilled RC structures in function of relevant design parameters and types of infill as well as to the development of recommendations for a more refined verification procedure aimed to provide enhanced damage control. These goals are achieved through an extensive analytical parametric study on newly designed RC structural configurations with different masonry infill typologies. Numerical models calibrated with reference to test results from previous experimental studies are adopted to evaluate the structural response based on nonlinear dynamic analyses. The influence of several design parameters is investigated, including building height, ground motion intensity, ductility class, and masonry typology. Referring to the current force-based seismic design practise for RC structures with masonry infills, particular attention is devoted to the existing inter-storey drift limits, and the implementation of improved design criteria in function of various design conditions is proposed. Considering the strong relation of in-plane and out-of-plane damage, the current research is primarily concentrated on the in-plane structural response and infill damage control; however, issues related to codified verifications of the out-of-plane stability of non-structural elements are addressed. The possible occurrence of local effects in RC frame structures due to the presence of masonry infills is also examined. The design approach introduced in this work may be supplemented with further design parameters, evaluated from other available test results.