An Innovated Technique for Retrofitting of Masonry Domes in Historical Buildings

Brick domes have been used as one of the most structural members in historical buildings such as mausoleums, religious centers and mosques. Low tensile strength of masonry constructions make them vulnerable to earthquake induced forces. Domes, under the gravity loads, are stable and strong enough, even though where tensile stresses exceed the tensile bearing capacity of masonry; cracks are appeared along the meridians. Under the earthquake loads these tensile stresses can be increased more seriously. Although, this drawback may be removed by post tensioning but conservation and restoration of historical buildings are very delicate operations requiring minimum interventions to save the original conception and historical value of the building. For this reason the applicable retrofitting techniques for historical buildings are very restricted. In this paper an innovated retrofitting technique using expanding grout is introduced. Expanding grouts is used for repointing of brick joints and creation of prestress forces between bricks. A nonlinear finite element model of a case study Khomar Taash brick dome in Jame mosque of Qazvin is developed using ABAQUS structural analysis software. Some of the required data for modeling of the dome are obtained from experimental works. In addition several vaults have been made and loaded to perceive the effectiveness of the method. The experimental and theoretical results show that the proposed technique can be effectively used for retrofitting of historical domes with a low level of intervention.