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Simplified dynamic analysis of eccentric buildings with a setback. 1: the effect of mass irregularity
Author(s) -
Georgoussis George K.
Publication year - 2011
Publication title -
the structural design of tall and special buildings
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.895
H-Index - 43
eISSN - 1541-7808
pISSN - 1541-7794
DOI - 10.1002/tal.567
Subject(s) - setback , structural engineering , eccentric , bent molecular geometry , tower , modal analysis , vibration , modal , reduction (mathematics) , mathematics , engineering , geometry , physics , finite element method , materials science , acoustics , civil engineering , polymer chemistry
SUMMARY The dynamic response of eccentric buildings with a setback is investigated and a simple method is proposed for assessing vibration frequencies and modal base shears and torques. With the proposed methodology the aforementioned basic dynamic quantities are determined by analysing first the symmetrical counterpart structure and then an equivalent one‐storey eccentric system. The type of buildings examined represents the class of tall structures with a significant reduction in the size of floor plans above a certain level, but without any modification on the structural system, which is considered to be uniform over the height of the building, but eccentric to the mass axis. It is shown that the vertical mass irregularity thus produced increases substantially the contribution of the higher modes of vibration to the total response of such structures and this contribution increases with the height of the tower structure above the setback level. A number of common buildings with a mixed‐bent‐type structural system are analysed by the proposed method and the results are compared with more accurate results obtained by three‐dimensional dynamic analyses. Copyright © 2009 John Wiley & Sons, Ltd.