Most residential buildings in Iran are constructed from unreinforced masonry walls (URM) which are often characterized by high seismic vulnerability. The majority of these structures were designed only for the gravity loads; therefore, they don't have adequate resistance and ductility against horizontally-applied loads such as those induced by earthquakes. When these structures are subjected to lateral loads applied by moderate and strong earthquakes, they collapse completely, causing massive

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... ath tolls and extensive losses. Iranian seismic history has shown that the majority of masonry buildings were completely destroyed under severe earthquakes, with a number of buildings with timber laces remaining safe and stable. In the past, timber framed masonry structures were built with no design guidelines and were solely based on the experience of traditional Iranian architects. Also, in the construction of these buildings, a form of wooden bracing system is used as the load carrying system. As a result, the buildings often show suitable seismic performance under severe earthquakes. Therefore, the main goal of this study is assessing the effects of timber ties on the seismic behavior of URMs. For this purpose, the plans of Iranian traditional buildings were reviewed and two groups of masonry models were selected to evaluate their seismic vulnerability. Nonlinear static analyses were performed on the models. The results demonstrated that confining masonry walls with timber increases the stiffness and capacity of the studied models. In addition, the performance level of the studied models can be modified from Collapse Prevention (CP) to Life Safety (LS). Also, the results showed that adding timber laces significantly increases the behavior coefficient of the masonry walls. It can therefore be concluded that timber laces significantly influence the performance of masonry structures.