Developing a seismic retrofitting solution for wall-to-floor connections of URM buildings with wood diaphragms

Out-of-plane collapse of masonry walls in unreinforced masonry (URM) buildings has been identified as a major local failure mechanism affecting the global stability of a structure. Continuity between structural elements maintains proper load paths during seismic action, discouraging the formation of out-of-plane mechanisms. This is a key factor for an engineer to consider when trying to fully utilize the in-plane capacity of a masonry wall. This paper focuses on the seismic retrofit of wall-to-floor connections of URM buildings with wood diaphragm floors. The solution consists of a tie rod bolted to a timber floor joist and anchored to the masonry wall using an anchor plate. Several cyclic pull-out tests were carried out to characterize the behaviour of the strengthened connection so that an 'engineered' strengthening can be developed. The resultant behaviour has the contribution of different failures from yielding of the steel components to masonry cone breakout. The strengthen connection presents a higher increase in tensile capacity, displacements, and consequently energy dissipation.