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Earthquakes and Structures
  Volume 3, Number 2, April 2012, pages 169-180
DOI: http://dx.doi.org/10.12989/eas.2012.3.2.169
 


Effect of ground motion characteristics on the pure friction isolation system
Radhikesh P. Nanda, Manish Shrikhande and Pankaj Agarwal

 
Abstract
    The performance of pure friction isolation system with respect to the frequency bandwidth of excitation and the predominant frequency is investigated. A set of earthquake ground motions (artificial as well as recorded [with different combinations of magnitude-distance and local site geology]) is considered for investigating effectiveness of pure friction isolators. The results indicate the performance of pure friction base isolated system does not only depend upon coefficient of friction and mass ratio but the stick-slip behaviour depends upon the frequency content of the excitation as well. Slippage prevails if the excitation frequency lies in a suitable frequency range. This range widens with increasing mass ratio. For larger mass ratios, the sliding effect is more pronounced and the maximum acceleration response is further reduced in the neighbourhood of frequency ratio (w/wn) of unity. The pure friction isolation system is effective in the case of broadband excitations only and that too, in the acceleration sensitive range of periods. The pure friction system is not effective for protection against narrow band motions for which the system response is quasi-periodic.
 
Key Words
    band-limited excitation; earthquake; ground motion characteristics; friction isolation; frequency content; shape factor
 
Address
Radhikesh P. Nanda: Department of Civil Engineering, NIT Durgapur, Durgapur, 713209, India
Manish Shrikhande and Pankaj Agarwal: Department of Earthquake Engineering, IIT Roorkee, Roorkee, 247667, India
 

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