Assessment of out-of-plane strength of masonry infills according to EC6

In the last decades the attention to the out-of-plane response of infills has been increasingly growing due to their influence on the global seismic behaviour of frame structures. In order to assess their out-of-plane capacity, different approaches have been proposed, such as those based on the arching effect and on the yield-line theory. Both methods are implemented in Eurocode 6 for masonry structures. The first approach is based on the observation that an arching effect develops in a wall provided that surrounding elements are able to resist thrust. The second approach consists in defining a kinematically admissible mechanism (yield-line mechanism) and calculating the limit load by equating the internal and external works. This method was implemented in Eurocode 6 (EC6) as well as in other codes by means of coefficients, which depend on the orthogonal ratio of the masonry flexural strengths, the degree of fixity at the edges of the wall and the wall aspect ratio. The suitability of the methods proposed in EC6 is investigated herein for masonry infills through comparison with experimental tests. It is found that, considering the second approach, the results are, on the average, conservative, contrary to the assumption that the method should provide an upper bound of the resistance.