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Mode superposition methods applied to linear mechanical systems under earthquake type excitation


Merchant, Howard Carl (1961) Mode superposition methods applied to linear mechanical systems under earthquake type excitation. Dissertation (Ph.D.), California Institute of Technology.


The determination of the maximum dynamic responses of a multidegree of freedom mechanical system under earthquake type excitation using mode superposition methods is the general problem considered. The experimental work was carried out using a special purpose electronic differential analyzer involving a three degree of freedom system, or a three mode approximation to a larger system.

The results indicate that a suitably weighted average of the sum of the absolute values and the square root of the sum of the squares of the individual mode contributions gives a practical design criterion for the base shear forces. For critical designs this weighted average reduces to the absolute sum of the modes, which will be close to the true value for a significantly high percentage of the cases. The base moment may be more accurately approximated than the base shear by use of the first mode alone.

Item Type:Thesis (Dissertation (Ph.D.))
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Mechanical Engineering
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Unknown, Unknown
Thesis Committee:
  • Hudson, Donald E.
  • Housner, George W.
  • Caughey, Thomas Kirk
Defense Date:1 January 1961
Record Number:CaltechETD:etd-04132006-153621
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1374
Deposited By: Imported from ETD-db
Deposited On:13 Apr 2006
Last Modified:26 Dec 2012 02:37

Thesis Files

PDF (Merchant_hc_1961.pdf) - Final Version
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