# A Review of the Performance of Infilled RC Structures in Recent Earthquakes
## 1 Introduction  
Observations on the performance of buildings during low, medium and strong earthquakes have served to increase the knowledge concerning the buildings seismic behaviour and specifically to identify proper and improper constructions and earthquake load-resisting systems. Design procedures have been developed in regions that have been inhabited, which are subjected to relatively frequent earthquakes, resulting in reasonably good seismic performances [1]. Although such design procedures are not universally applicable due to regional differences, structural engineers can learn by studying those procedures in terms of construction materials and techniques. Apart from that, the post-earthquake damage reconnaissance reports highlighted the importance of the masonry infill walls in the seismic performance of the reinforced concrete (RC) building structures. [PERSON] et al. [2] pointed out that these elements, usually called 'non-structural' elements by the structural design codes, may play an essential role in structural behaviour and are responsible for a significant part of the human, material and economic losses, as proved in the Lorca earthquake in 2011 [3]. The same observation was made in 2016 by [PERSON] et al. [4], when a Mw 6.0 earthquake occurred in Central Italy, causing severe damages to infilled RC structures [5]. The RC structures behaviour depends on the structural elements' stiffness, strength, ductility and energy-dissipation characteristics, among other factors [6]. The building structural strength is provided by each structural member and the interaction and connection between them [7]. Since the buildings are structures with a high degree of redundancy, their response is controlled by the loading redistribution capacity, which can fail if some of the members reach the failure and the remaining ones cannot accommodate significant deformations before failure. The insufficient strength capacity of some structural members can be justified by being subjected to seismic loading demands significantly higher than the values considered during their design process. The structures should be designed according to the expected seismic demands prescribed by the modern codes to ensure adequate stiffness, strength and ductility to the elements and, consequently, the global structure. The seismic design of RC structures needs to be performed by considering the RC structural elements and secondary elements and non-structural elements like the masonry infill walls. Some international codes like Eurocode 8 [8] consider the infill panels as non-structural elements and provide low importance to their seismic behaviour and participation in the response of the building. Their contribution to the seismic structure response is usually disregarded. The Nepalese earthquake in 2015 evidenced that the infill walls often play an essential role in the seismic response of the RC structures [9]. They provide an increment of stiffness, strength, and energy dissipation to the global structure. They change the natural periods and vibration modes of structures, attracting higher seismic loadings than those expected during the design process [6]. Nevertheless, their in-plan and in-elevation distribution can also affect negatively the global structural response [10]. The infills walls presence reduce the building deformation capacity and can potentiate failure mechanisms that the structural members were not designed to support [11]. This manuscript aims to present the most representative types of damage observed in infilled RC structures due to earthquakes. Those damages are divided according to the ten most representative types. The main reasons that could trigger each damage type are presented. A detailed discussion is presented concerning the infill walls seismic behaviour and their interaction with the RC structures.