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Abstract: The seismic performance of structures with irregular distribution of mass, stiffness and strength along the height, may be significantly different compared to regular structures, depending on the limit-state or the level of seismic intensity considered. In the framework of probabilistic performance based earthquake engineering, it is possible to quantify the effects of vertical irregularities on the seismic performance of structures. In this study, the seismic performance of different non-geometric vertical irregular structures is compared to a regular structure at various performance levels with a probabilistic approach. The results show that the non-uniform distribution of lateral resisting properties over the height of structure influences the seismic performance, especially at the limit-states close to collapse until global dynamic instability. These effects may be on the seismic intensity capacity and/or on the ductility capacity of the structure, based on the type and the position of vertical irregularities. Also from the standpoint of a probabilistic seismic performance based design, the vertical irregularities increase the mean annual frequency of exceeding the GI performance level by about 5% to 30%. [Copyright &y& Elsevier]

This study adopts a random procedure in the evaluation of the effect of the rotational component of earthquake on the accidental eccentricity of symmetric and asymmetric buildings. The spectral density function of the rotational component of earthquake acceleration (about the vertical axis) is obtained on the basis of the spectral density function of the horizontal component of earthquake acceleration. The rotational component of an earthquake can increase the response of the structure. The degree of the increase is highly dependent upon the dynamic characteristics of the system and the rotational component of the earthquake. To bring this increase under consideration, seismic codes represent a parameter referred to as accidental eccentricity, as a part of the design eccentricity. The purpose of the present study is to estimate the value of this increase and to make appropriate suggestions based on frequency domain analysis. [ABSTRACT FROM AUTHOR]