The Improving of the Seismic Performance of Existing Old Public Unreinforced Masonry Buildings

Abstract

The paper is devoted to historical masonry buildings protection against the destructive influence of earthquakes. Strengthening such buildings that were not originally designed to resist seismic actions became a common practice in structural engineering in Romania. Seismic retrofitting of the cultural heritage, especially of the historic buildings, requires compliance with the severe restrictions of the Romanian legislation related to the preservation of the original artistic and structural features. That’s why the technical assessment, the strengthening followed by the rehabilitation of an old heritage building became an engineering “art” with a firm “scientific base”. After a very short presentation on the evolution of the masonry buildings in Romania, the paper deals with the study of a prototype of such a building in Constanţa city, within which “The National History and Archeology Museum” is located. To perform the technical assessment of the above mentioned building a theory of damage and failure of unreinforced masonry walls was applied. This theory was conceived by the Romanian engineer Emilian Ţiţaru when he studied the behavior of masonry buildings in Karpos district, after the July 26, 1963 Skopje earthquake. For the strengthening of the museum building the concept of “spectral position” was used. Some information on the use in Romania of the concept of “base isolation” is also given. 1. MASONRY BUILDINGS IN ROMANIA. A SHORT HISTORY. As in most countries of the world, buildings with structural systems – masonry walls type, were the most frequent ones used in the past. For many centuries masonry buildings have been “designed” by using some practical rules derived from well defined ratios among the dimensions of the main structural elements, based on experience acquired over the years. Even after the evolution of most specific theoretical background in the field of the theory of structures at the end of the XIX century and the beginning of the XX century, the design of masonry buildings has been mostly done through the same old established procedures. The beginning of the XX century marked the introduction of new materials in the structural systems of masonry buildings, such as reinforced concrete and steel. In the above mentioned period hundreds of thousands of rural residential and hundreds of public buildings with solid bricks structural walls have been built in Romania. From the second class of existing masonry type buildings, the most representative are those for: public services, military, education, health and culture (theatres, cinema, and museums).