Seismic rehabilitation of URM heritage-listed Namazi school building using multiple retrofitting techniques

Abstract

When dealing with retrofitting historical URM buildings, two prime aspects of their weakness against seismic action should be considered. These include: (i) the capacity of structural elements, such as foundations, masonry walls and floors, to resist earthquake forces and (ii) the integrity of the building as a whole under ground shaking. In this paper, different retrofitting techniques adopted to counter the above weaknesses in rehabilitation of the heritage-listed Namazi high school buildings are discussed. Extensive field investigations were first carried out to determine the detailed architectural and structural forms of the buildings, as well as, their material types and properties. It was found that in constructing the historic school buildings, traditional Iranian construction techniques and materials were used alongside some more modern elements such as reinforced concrete and masonry jack arch slab systems. This made the buildings unique in form, hence more challenging to retrofit. Seismic vulnerability studies were then carried out to evaluate the weaknesses of structural elements and the buildings as a whole. Different retrofitting techniques were then selected and applied to overcome the weaknesses. Effectiveness, cost and architectural constraints were the main considerations in selecting the retrofitting techniques for different parts of the historical buildings from a pool of different available methods. The techniques used in enhancing the seismic capacity of structural elements included: reinforced shotcrete overlay for masonry walls, FRP overlay for RC floors and beams, steel confinement and bracing of masonry jack arch floor systems and RC ground-beam confinement of brick and stone masonry foundations. To enhance the overall integrity of the buildings through confinement, vertical and horizontal steel tie elements and reinforced concrete tie elements were used.