THE METRHOD OF INCREASING LEVEL OF SEISMIC SAFETY OF EXISTING BUILDINGS

This paper is devoted to development of the method for increasing a seismic safety level of existing buildings and constructions having insufficient seismic safety level due to the changing of seismic zoning maps and requirements of new Codes on Earthquake Engineering. There is a considerable number of buildings in many cities in seismically active countries of the world, which have insufficient safety margin in case of severe earthquakes. These buildings with perfect architectural appearances and comfortable conditions were designed and erected ۲۰-۳۰ years ago for inhabitants or offices according to the old Codes, in which the level of seismic effect considerably differed from contemporary Codes on Aseismic Building. During severe earthquakes serious damages of these buildings, which cause the loss of people lives and material assets, are expected. The problem of reinforcement of these buildings is of great social-economical, psychological and moral importance. National programs on reconstruction and reinforcement of such buildings are developed in many countries. During the reinforcement process for existing buildings the main aspects are temporarily evacuation of inhabitants and preservation of architectural appearance of buildings. It is the most delicate one, because it is related to great material expenditures, people's psychological training, especially for residential multi-story buildings, where a large number of families live. The experience of many countries of restoration and reinforcement of old buildings shows that a lot of efforts and time are required for the authorities to obtain the inhabitants' consent for temporary evacuation and their allocation in other buildings. The architectural appearance of a whole building will also significantly suffer during the traditional ways of reinforcement by additional increasing the sizes of bearing elements (columns, crossbars and building walls).