Dynamic characteristics of traditional

The adobe-quincha system is a traditional construction technology that was used widely in Peru during the colonial period and at the beginning of the republican era. At present this constructions are located in the old part of the main cities of Peru like Lima, Arequipa, and Trujillo. These cities are trying to preserve these old constructions since they form part of their historical centres. This system was used to construct mainly particular residences and sometimes palaces, and consist of a first floor made of adobe or sun-dried bricks and upper floors made of quincha. The quincha is formed by wooden frames or panels which support a mesh of cane to receive a finishing plaster of mud and gypsum. Apparently, from experiences of past earthquakes that strike Peruvian cities, a second floor or upper floors made of light material provided better seismic behaviour. However since the basic material is earth (earthen constructions) is obvious that appropriate maintenance and conservation task are necessary. Therefore, in this research, a preliminary evaluation of structural condition of these kinds of buildings is performed. As example, a building that was used as hotel is presented, where ambient vibration measurements were performed to estimate its period of vibration. The building presents some partial collapse of interior walls and serious deterioration of the quincha walls. Although light weight of the upper stories could signify a better seismic behaviour, deterioration and lack of repair and maintenance make critical the vulnerability of these buildings