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Dynamic analyses of suspension bridge structures

Abdel-Ghaffar, Ahmed Mansour (1976) Dynamic analyses of suspension bridge structures. California Institute of Technology . (Unpublished) http://resolver.caltech.edu/CaltechEERL:1976.EERL-76-01

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Abstract

A method of dynamic analysis for vertical, torsional and lateral free vibrations of suspension bridges has been developed that is based on linearized theory and the finite-element approach. The method involves two distinct steps: (1) specification of the potential and kinetic energies of the vibrating members of the continuous structure, leading to derivation of the equations of motion by Hamilton's Principle, (2) use of the finite-element technique to: (a) discretize the structure into equivalent systems of finite elements, (b) select the displacement model most closely approximating the real case, (c) derive element and assemblage stiffness and inertia properties, and finally (d) form the matrix equations of motion and the resulting eigenvalue problems. The stiffness and inertia properties are evaluated by expressing the potential and kinetic energies of the element (or the assemblage) in terms of nodal displacements. Detailed numerical examples are presented to illustrate the applicability and effectiveness of the analysis and to investigate the dynamic characteristics of suspension bridges with widely different properties. This method eliminates the need to solve transcendental frequency equations, simplifies the determination of the energy stored in different members of the bridge, and represents a simple, fast and accurate tool for calculating the natural frequencies and modes of vibration by means of a digital computer. The method is illustrated by calculating the modes and frequencies of a bridge and comparing them with the measured frequencies.


Item Type:Report or Paper (Technical Report)
Additional Information:PB 258 744/AS
Group:Earthquake Engineering Research Laboratory
Record Number:CaltechEERL:1976.EERL-76-01
Persistent URL:http://resolver.caltech.edu/CaltechEERL:1976.EERL-76-01
Usage Policy:You are granted permission for individual, educational, research and non-commercial reproduction, distribution, display and performance of this work in any format.
ID Code:26427
Collection:CaltechEERL
Deposited By: Imported from CaltechEERL
Deposited On:28 Nov 2001
Last Modified:26 Dec 2012 13:57

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