Coupled Systems Mechanics, Vol. 5, No. 2 (2016) 127-144 DOI: http://dx.doi.org/10.12989/csm.2016.5.2.127 127 Copyright © 2016 Techno-Press, Ltd. http://www.techno-press.org/?journal=csm&subpage=7 ISSN: 2234-2184 (Print), 2234-2192 (Online) Influence of interface on the behavior of infilled frame subjected to lateral load using linear analysis K. Senthil 1 and K.S. Satyanarayanan 2 1 National Institute of Technology Jalandhar, Punjab 144011, India 2 SRM University, Kattankulathur, Kancheepuram, TamilNadu 603203, India (Received March 19, 2016, Revised May 9, 2016, Accepted May 10, 2016) Abstract. Two dimensional numerical investigations were carried out to study the influence of interface thickness and their pattern on the behavior of reinforced concrete frames subjected to in-plane lateral loads using commercial finite element tool SAP 2000. The linear elastic analysis was carried out on one and two bay structural systems as well as the influence of number of stories was studied by varying the number of stories as single, three and five. The cement mortar was used as interface material and their effect was studied by varying thicknesses as 6, 8, 10, 14 and 20 mm. The interface was recognized as one sided, two sided, three sided and four sided and their effect was studied by removing the interface material between the reinforced concrete frame and masonry infill. The effect of lateral loads on infill masonry wall was also studied by varying assumed loads as 10, 20, 30, 40, 50 and 60 kN. The behavior of infilled frames studied has revealed that there is a maximum influence of interface thickness and interface pattern corresponding to 10 mm thickness. In general, the lateral displacement of frame is increased linearly with increase in lateral loads. Keywords: finite element method; interface thickness; interface pattern; in-plane lateral loads; maximum principal stress 1. Introduction Recent earthquakes in Nepal (2015), Bhuj (2001), Turkey (Kocaeli 1999, Duzce1999, Bingol 2003) have demonstrated large seismic demands that were not accounted for in their design. Most of the weakest spot of the building are reinforced concrete frame element and infill masonry wall element which in spite of bonding layers of interface element. The post-earthquake reconnaissance surveys showed (Dogangun et al. 2008) the lack of lateral strength together with masonry infill, frame element and interface element for collapse in most cases. According to Erdik and Aydınoglu (2003), in urban areas, 30% buildings were reinforced concrete frame, 48% were brick masonry and 22% were adobe or rubble masonry. In rural areas, 82% of buildings were brick masonry while 18% were reinforced concrete frame. Therefore, the safety of the masonry building is very important in the moderate to severe seismic zones, as 90% of the world population lives and works in masonry buildings and these buildings should be protected during earthquakes. Corresponding author, Assistant Professor, E-mail: urssenthil85@yahoo.co.in