Out-of-Plane Response of Infill Masonry Walls

Abstract

The in-plane effect of infill walls on the structural response of reinforced concrete frames has been widely acknowledged via numerous experimental and numerical investigations and, as a result, the need to consider their effect on structural response has been acknowledged (indicated) in the latest generation of structural design codes worldwide. Due to the uncertainties concerning the behavior of masonry at the material and structural level, the latter elements are usually ignored during the structural analysis phase. They are only considered when (i) there is suspicion that their influence can be detrimental on the overall structural response or on the behavior of individual structural - loadbearing - elements or (ii) when it is necessary to justify an elevated overall load-carrying capacity of an existing frame structure. In the latter case, both the in-plane and out-of-plane behavior can potentially play significant roles in accurately determining the overall load-carrying capacity of the frame structure at hand. To date, emphasis has been placed on investigating the in-plane contribution of the infill walls on the overall structural response whereas the effect of the out-of plain behaviour of the infill walls has been less studied. Should the infill walls fail in the out-of-plane direction, then any calculations performed on the basis that they can sustain in-plane loading would be inaccurate. In the present study a model is proposed, which allows one to estimate which infill walls do not exhibit out-of-plane collapse and in doing so, continue participating in the structural model with their in-plane stiffness and bearing capacity. The predictions of the proposed analytical model are verified experimentally via shake table testing.