Engineering Mechanics

Proceedings Vol. 8 (2002)

INŽENÝRSKÁ MECHANIKA 2002

ENGINEERING MECHANICS 2002

Copyright © 2002 Institute of Mechanics of Solids, Faculty of Mechanical Engineering, Bruno University of Technology, Brno

 

Jiří Náprstek, Miroš Pirner, Cyril Fischer
pages 195 - +8p., full text

Long-term observation of bridges supported by bearings made of synthetic materials reveals a steady horizontal deformation increase of these elements. This process can be very dangerous for the bridge as a whole. Therefore an applicable theoretical model should be developed and implemented to predict the level of these deformations and to give adequate recommendations to design practice. While a short-term response corresponds rather with the Voigt model, the long-term records have a trend of a non-uniform increase of deformations respecting the Maxwell model. Therefore influences of horizontal time variable loading can accumulate successively. The process of an increase can be either stabilized approaching to horizontal asymptotic line or it can lose the stability in a certain moment and starts to rise beyond any limits. The mathematical model of the system is composed ofVoigt and Maxwell elements in a form of a system of linear differential equations. The system is solved either directly or in an integro-differential form using the Laplace transformation. The general and several special cases of external excitation are investigated in details. Closed form results are presented for impulse and Heaviside types of the loading. Experimental measurement in a laboratory and approximative analyses have been done and compared with results obtained by theoretical investigation.

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