2nd Croatian Conference on Earthquake Engineering 2CroCEE

The structural response due to the seismic load depends on the dynamic structural properties and incoming ground motion. Although for low amplitude ground motions the material behaviour is assumed to be linear, as the amplitude increases the dynamic properties of the structures are changed so that the nonlinear effects should be considered.
In determining the nonlinear characteristics of structures the vibrational periods are important step to be followed. On the other hand, the local site effects have impact on earthquake motion alteration which in most cases contribute to the dynamic amplification of the ground motions. The definition of natural periods of existing buildings including the foundation structure of the whole system can be done by in-situ experimental methods. These experimental methods being cost-effective are constituted by various techniques relating the measurement of structural natural vibrations.
This work sums up the experience of UKIM-IZIIS in measuring the in-situ dynamic characteristics of different types of buildings in N.Macedonia. The measurements are based on ambient vibration using the newest technological methods. The established data-base apart from the vibrational periods includes the geometrical and structural properties of the measured structures which are shown in this paper.
The results have shown that apart from geometry the material characteristics play important roles in definition of dynamic characteristics of the structures. The inclusion of brick masonry infills in the final establishment of the dynamic properties plays important role and should be considered in the analysis of the structural analysis. Last but not least is the definition of representative hazard which indirectly influences the dynamics of the structures.