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A considerable number of existing buildings in seismic prone countries has been constructed either based on earlier concepts for seismic design or without applying seismic provisions. As a consequence, their seismic upgrade is a matter of concern. In urban environments, these structures usually consist of reinforced concrete (RC) frames with brick infill walls. Their strengthening with traditional methodologies, such as concrete jackets and shear wall construction, often results in operation interruption and high cost. The present research examines the complex response of RC frames and brick infill walls strengthened with Fibre Reinforced Polymers (FRP), a recently proposed retrofit scheme that becomes attractive because of its low cost and ease of implementation. Instead of the commonly used pair of compression struts that models the infill wall, a multiple strut masonry panel element model with advanced constitutive laws is applied for the representation of the nonlinear response of the infill wall, while a tension tie is used to consider the FRP sheets contribution on the response. The parameters of the wall and the FRP elements that are used in the numerical model are calibrated against experimental results available in the literature for two-storey, one-bay reinforced concrete frames subjected to cyclic loading. The effectiveness of this innovative technique is presented considering the response of the masonry infilled RC frame with and without retrofit. By comparison of the results, conclusions are drawn concerning design procedures.

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In this Chapter a triple-domed basilica constructed at the end of the 19th century is selected as a case study to present a methodology for the selection of the appropriate intervention techniques in monumental structures. The methodology includes in-situ and laboratory testing, application of analytical methods, consideration of geotechnical parameters and regional seismicity. Seismic loads are estimated according to contemporary and older concepts for seismic design. Since the impact of near-fault phenomena on masonry structures has not been thoroughly studied, although considered as responsible for extensive structural damage during major seismic events, a procedure is presented in order to account for the special characteristics of strong ground motion, in the so-called near-fault region. The seismic performance of the structure before and after interventions, using traditional and new technology, is assessed by applying a validated finite element model. Also, the out-of-plane behavior of structural parts is evaluated through kinematic analysis of selective collapse mechanisms.