Importance of wood and iron tension members on seismic performance of historic masonry buildings: Three case studies from Turkey

Wood and/or iron tension members in the form of either tie bars (both wood and iron) in historic masonry arches or externally applied tension rings (iron) of masonry domes have been used in historic buildings especially in the areas that are vulnerable to severe earthquake excitations. Earthquake reconnaissance investigations revealed that masonry arches and domes with tension members showed satisfactory behavior under earthquake loading. To investigate their effectiveness on behavior, three case studies are analyzed from Turkey. The first one is a 16th century mosque having major structural cracks on its 25m-diameter brick masonry dome. Combined steel and CFRP sheets as tension members at several dome levels are proposed as a seismic retrofit measure. Significant improvement is obtained in response, leading to maximum 60% reduction in stresses. The second case study is a stone masonry vault having damaged wooden tie bars. Similarly, numerical results show that stresses as well as deformations can be reduced up to 50% by replacing the old ties with the new wooden tie bars. The third one is a 508-year-old tomb having a nearly collapsed brick masonry dome. At the support level of the dome, externally applied steel rings were used as tension members to limit stresses and deformations. Similar amounts of reductions in stresses are obtained. This study also shows that both traditional and contemporary retrofit strategies can be used in the same project when required.