Periods of Vibration for Displacement-Based Assessment of RC Buildings





ABSTRACT
Simple empirical relationships are available in many design codes to relate the height of a building to its fundamental period of vibration. These relationships have been realized for force-based design and so produce conservative estimates of period such that the lateral shear force will be conservatively predicted from an acceleration spectrum. Where assessment of a structure is concerned, it is the displacement demand that gives an indication of the damage that can be expected, this displacement would be underestimated with the use of the aforementioned period – height formulae. Furthermore, the period of vibration of interest in assessment is the yield period, which is calculated using the yield stiffness, also often referred to as the cracked or elastic stiffness. The derivation of a yield period – height formula for use in displacement-based assessment of European buildings is thus the focus of this dissertation. Analytical fibre element models of RC frames of varying height have been developed and the yield period has been sought using eigenvalue, pushover and dynamic analyses. Keywords: displacement; assessment; period; yield; RC buildings;


ACKNOWLEDGEMENTS
The author wishes to thank in particular Dr Rui Pinho for all of his guidance and support throughout the duration of this research project and his invaluable critique during the final stages of the dissertation. In addition, this work has greatly benefited from the comments and advice of Professor Nigel Priestley. Also, the author is grateful to Professor Shunsuke Otani for introducing the work of Professor Shunsuke Sugano during his lectures at the ROSE School, Pavia which proved most useful to the research project. Furthermore, the author would like to thank Professor Shunsuke Sugano himself, for his kind assistance in supplying data from his past work.

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