A Comparative Study Of Modelling The DynamicCharacteristics Of A Solid-stone Masonry Tower

Measured dynamic properties of an unreinforced stone masonry tower were used as a basis to compare the results of three analytical methods, simplified, frame analysis and finite element method. The results revealed that all three methods yield the first dynamic mode provided it is first calibrated by the corresponding measured value, but only the results obtained from the finite element method compared well with the experimental data up to the fifth dynamic mode. None of the analytical models used were able to reproduce the loose boundary interface between the roof and the masonry wall obtained experimentally. 1 Background In North America, a large number of historic buildings are labeled unreinforced masonry (URM) and were generally constructed without seismic considerations. Consequently, there is a need to assess the seismic adequacy of such structures located in moderate to high risk earthquake zones. The first step in assessing the dynamic behaviour of structures when subjected to seismic ground motion is by determining their dynamic properties. The natural frequencies, mode shapes and damping of the structure are pre-requisites for determining the forces affecting a historical building. The calculation of natural frequencies is not precise because parameters such as material properties and boundary conditions are unknown. Nevertheless, in this study the different numerical methods, namely a simplified method, the frame analysis and the finite element method are examined to assess their suitability for calculating the dynamic characteristics of thick stone Transactions on the Built Environment vol 15, © 1995 WIT Press, www.witpress.com, ISSN 1743-3509