Farhad AKHOUNDI۱ - PhD Stude nt, ISISE, University of Minho, Guimaraes, Portugal
Graça VASCONCELOS - Assistant Professor, ISISE, University of Minho, Department of Civil Engineering, Portugal
Paulo B. LOURENÇO - Professor, ISISE, U niversity of Minho, Department of Civil Engineering, Portugal
Carlos PALHA - Engineer, Univerrsity of Minho, Department of Civil Engineering, Portugal

In order to investigate the o ut-of-plane behaviour of masonry infill walls, quasi-static testing was performed on a masonry infill walls built inside a reinforced concrete frame by mea ns of an airbag system to apply the uniform out-of-plane load to each component of the infill. The main advantage of this testing setup is that the out-of-plane loading can be applied more uniformly in the walls, contrarily to point load configuration. The test was perform ed under displacement control by selecting the mid-point of the infill as control point. Input and output air in the airbag was controlled by using a softw are to apply a specific displacement in the control point o f the infill wall. The effect of the distance betw een thereaction frame of the airbag and the masonry infill on the effective contact area was previously analys ed. Four load cells were attached to the reaction frame to me asure the out-of-plane force.The effective conta ct area of the airbag was calculated by dividing the load me asured in loadcells by the pressure inside the ai rbag. When the distance between the reaction walls and the masonry infill wall is smaller, the effective area is closer to the nominal area of the airbag.Deformation and crack patterns of the infill confirm the formation of arching mechanism and two-way bending of the masonry infill. Until collapse of the horizontal interface between infi ll and upper beam in RC frame, the infill bends in two directions but the failure of that interface which is kno wn as weakest interface due to difficulties in filling the mortar between bricks of last row and upper be am results in the crack opening trough a well-defined path and the consequent collapse of the infill.

Masonry, Infill, Out-of- Plane, Airbag