In-plane and out-of plane experimental characterization of rc masonry infilled frames

2015-07-01

Akhound, Farhad; Vasconcelos, Graça; Lourenço, Paulo B.; Palha, Carlos Alberto Oliveira Fernandes; Silva, Luís C.

Masonry infills; In-plane behavior; Out-of-plane behavior; Airbag testing

Seismic investigations of typical south European masonry infilled frames were performed bytesting two reduced scale specimens: one in the in-plane direction and another in the out-ofplanedirection. Information about geometry and reinforcement scheme of those structuresconstructed in 1980s were obtained by [1]. The specimen to be tested in the in-plane directionwas constructed as double leaf masonry while the specimen for testing in the out-of-planedirection is constructed with only its exterior leaf since the recent earthquakes havehighlighted the vulnerability of the external leaf of the infills in out-of-plane direction [2].The tests were performed by applying the pre-defined values of displacements in the in-planeand out-of-plane directions in the control points. For in-plane testing it was done by hydraulicactuator and for out-of-plane testing through the application of an airbag. Input and output airin the airbag was controlled by using a software to apply a specific displacement in thecontrol point of the infill wall. Mid-point of the infill was assumed as a control point for outof-plane testing.Deformation and crack patterns of the infill confirm the formation of two-way archingmechanism of the masonry infill until collapse of the upper horizontal interface between infilland frame which is known as weakest interface due to difficulties in filling the mortarbetween bricks of last row and upper beam. This results in the crack opening through a welldefinedpath and the consequent collapse of the infill.