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Energy Radiation from a Multi-Story Building


Favela, Javier (2004) Energy Radiation from a Multi-Story Building. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/SNYE-QG70.


Damping limits the resonance of vibrating systems and thus higher anelastic damping is generally favored for engineered structures subjected to earthquake motions, because it means that a structure can dissipate a larger percentage of its energy per oscillation cycle. However, there are elastic processes that can mimic the effects of anelastic damping. In particular, buildings lose kinetic energy when their motion generates elastic waves in the Earth, which is referred to as radiation damping. Unlike anelastic damping, strong radiation damping may not always be desirable, as reciprocity can be used to show that buildings may be strongly excited by elastic waves of similar characteristics to those generated by the building's forced vibrations. As a result, it is important to quantify the radiation damping of structures to be able to improve their design.

Several experiments using Caltech's nine story Millikan Library as a controlled source were performed to investigate the radiation damping of the structure. The building was forced to resonate at its North-South and East-West fundamental modes, and seismometers were deployed around the structure in order to measure the waves generated by the library's excitation. From this "local" data set, we determine the elastic properties of the soils surrounding the structure and estimate what percentage of the total damping of the structure is due to energy radiation. Using Fourier transforms, we were also able to detect these waves at distances up to 400 km from the source using the broadband stations of the Southern California Seismic Network. This "regional" data set is used in an attempt to identify arrival times and to constrain the type of waves being observed at regional distances.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:forced vibration; regional displacements; seismic waves; signal velocity; structural damping
Degree Grantor:California Institute of Technology
Division:Geological and Planetary Sciences
Major Option:Geophysics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Heaton, Thomas H.
Thesis Committee:
  • Clayton, Robert W. (chair)
  • Kanamori, Hiroo
  • Tromp, Jeroen
  • Hall, John F.
  • Heaton, Thomas H.
Defense Date:29 April 2004
Record Number:CaltechETD:etd-06032004-143147
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:2417
Deposited By: Imported from ETD-db
Deposited On:03 Jun 2004
Last Modified:27 Jan 2021 20:14

Thesis Files

PDF (JFavela-DoubleSideFinal.pdf) - Final Version
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PDF (JFavela-SingleSideFinal.pdf) - Final Version
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