Estimating the elastic period of masonry towers C. Rainieri 1 , G. Fabbrocino 2 1 Ph.D., Research associate, Structural and Geotechnical Dynamics Laboratory StreGa, University of Molise, Via Duca degli Abruzzi – 86039Termoli, Italy 2 Associate Professor, Structural and Geotechnical Dynamics Laboratory StreGa, University of Molise, Via Duca degli Abruzzi – 86039Termoli, Italy Abstract The fundamental period of vibration plays a primary role for the assessment of the seismic demand on structures. It can be evaluated by numerical analyses, or even according to basic formulations provided by building codes for common structural typologies. In the present paper, the results of an extensive experimental campaign based on output-only modal identification of masonry towers in the Molise region (South- ern Italy) are presented. The collected data, including information about geometry and material properties of the towers, have been analyzed and combined with those derived from an extensive literature review, to identify the main parameters influencing the value of the fundamental period of Italian masonry towers. The re- sulting database has been useful first of all to check the effectiveness of available formulations for prediction of the fundamental period of masonry towers reported in building codes. Moreover, correlations between the fundamental period of ma- sonry towers and relevant geometric parameters are illustrated and discussed in order to develop a novel formulation providing the fundamental period of Italian masonry towers as a function of the height. Proceedings of the SEM IMAC XXX Conference Jan. 30 – Feb. 2, 2012, Jacksonville, FL USA ©2011 Society for Experimental Mechanics Inc.