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Analytical Models for the Dynamics of Buildings


Jain, Sudhir Kumar (1983) Analytical Models for the Dynamics of Buildings. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/4k04-ca84.


This thesis investigates the significance of in-plane floor flexibility on the dynamics of buildings, and develops analytical models for structures that have flexible floor diaphragms. Experience with past earthquakes demonstrates that this feature is particularly important for long, narrow buildings and buildings with stiff end walls. In the method developed in this study, the equations of motion and appropriate boundary conditions for various elements of the structure are written in a single coordinate system and then are solved exactly.

One- and two-story buildings with end walls are analyzed by treating their floors and walls as bending and shear beams, respectively. The resulting equations of motion and the boundary conditions are solved to obtain the dynamic properties of the structure. The expected low torsional stiffness of the end walls or frames is confirmed by analysis of a single-story example structure. Study of a similar two-story building showed that the first two modes, dominated by the floor and the roof vibrations, make the largest contributions to the total base shear in the structure.

Floors of multistory buildings with end walls (or frames) are idealized as equivalent, distributed beams while the walls or frames are treated as bending or shear beams. Analysis of a nine-story building showed that the structure possesses several lower modes in which floors vibrate essentially as pinned-pinned beams.

Buildings with large numbers of uniform stories and frames (or walls) are treated as vertically-oriented anisotropic plates. It is concluded that the floors in such buildings can be assumed rigid for seismic analysis, since the modes involving floor deformations are not excited by uniform ground motion.

The approach can be generalized further to study more complex structures. An example is the Imperial County Services Building, which has two end walls in the upper stories and several walls in the ground story. The analytical model of this building predicts several important features of the complex dynamic behavior of the structure.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Civil Engineering
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Civil Engineering
Awards:Caltech Distinguished Alumni Award, 2022.
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Jennings, Paul C.
Group:Earthquake Engineering Research Laboratory, Caltech Distinguished Alumni Award
Thesis Committee:
  • Jennings, Paul C. (chair)
  • Housner, George W.
  • Babcock, Charles D.
  • Caughey, Thomas Kirk
  • Kanamori, Hiroo
Defense Date:25 May 1983
Other Numbering System:
Other Numbering System NameOther Numbering System ID
EERL Report83-02
Funding AgencyGrant Number
Record Number:CaltechTHESIS:08162019-113014700
Persistent URL:
Related URLs:
URLURL TypeDescription ItemTechnical Report EERL 83-02 in CaltechAUTHORS
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11761
Deposited By: Bianca Rios
Deposited On:16 Aug 2019 19:20
Last Modified:26 May 2022 22:23

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