EXPERIMENTAL TESTS OF R/C FRAMES WITH MASONRY INFILL V. Sigmund, J. Zovkić University of Osijek, Faculty of Civil Engineering Osijek, Croatia Z. Sigmund University of Zagreb, Faculty of Civil Engineering Zagreb, Croatia ABSTRACT: Structural frames are often filled with masonry serving as partitions or cladding. Studies have demonstrated that infilled frames perform better than corresponding bare frame but the only feasible way to account for the effects of infill is to directly include the infill in the analytical model used for design. In order to test the numerical models and to define a simple method for analyzing the behavior of reinforced concrete frames with infill in earthquake regions we have done a series of tests with the aim to investigate the behavior of infilled r/c frames under seismic loads. Model frames represent part of a model structure. They were designed according to the EC8, modeled in a scale 1:2.5, infilled with three types of masonry and tested under constant vertical and cyclic horizontal loading. Presented is the relationship between drift capacity and properties of the frame-wall system controlling drift capacity. Keywords: r/c frames, infilled frames, masonry infill, in-plane loading, experimental tests 1. INTRODUCTION The vulnerability of unreinforced masonry to earthquake became evident to industrial society as early as in Naples, 1857, and Messina, 1908. Specific flaws in unintentional frame-wall systems were identified in the aftermath of the Skopje Earthquake of 1963. They were: (1) weakness introduced by openings in the wall, (2) captive columns, (3) out-of-plane collapse of walls, and (4) column failures under reversals of combinations of shear and tensile or compressive forces. These flaws have continued to cause tragic consequences in subsequent urban earthquakes with the most recent examples occurred in profusion in Wenchuan (2008) and L’Aquila (2008). A review of the literature on infilled-frames shows that consensus on the effects of the interaction between frames and in-plane masonry walls is lacking. Some researchers have suggested that infill walls have led to collapse of buildings and that infill walls may affect the response of frames detrimentally. Some others have suggested that masonry infill panels may be beneficial. Dolsek and Fajfar (2008) captured the essence of the problem stating: “The infill walls can have a beneficial effect on the structural response, provided that they are placed regularly throughout the structure, and that they do not cause shear failures of columns.” The existence of contradictions in the views of the research community have led to the deconstruction of the frame-wall system by many regional building codes that contain warnings about the interaction of frames and walls but are mostly silent on providing recommendations and bounds on their proper proportioning. That has been the driving reason for the proposed project. In multi-story construction, the most important attribute of the structure is its capability to [-] retain its integrity at story drift ratios on the order of 1.5%-2%. The results of neural-network analysis (Sigmund-Kalman,2009) based on approximately 100 tests of one-bay one-story infilled frames available in literature have demonstrated that drift ratios of that magnitude can be achieved by a