Elaboration d'un isolateur a la base original pour les ponts et viaducs au Canada (French text)

This study presents the development, the design and the experimental validation in laboratory of an original seismic base isolator for bridges in Canada. The proposed seismic bearing is unidirectional and is made of two structural components: a frictional component, based on a pot bearing, which represents the dissipative part of the isolator, and a spring component which insures re-centering of the bearing and limits the seismic displacements.; This thesis is based on a literature review on base isolation, on the development of numerical models for dynamic analysis, on the application of well known technologies such as friction systems or elastomeric bearings in one hand, and on the development of new technologies such as Shape Memory Alloys or simply the adaptation of structural springs for seismic applications in Civil Engineering. Theoretical studies led to the elaboration of a superelastic rule without viscosity. Moreover, each component of the bearing was validated experimentally. Frictional tests on an interface made of stainless steel and teflon allowed the study of sliding at high frequencies and clearly showed the differences between static coefficient and dynamic coefficients of friction in steady state. A numerical model is proposed to take in account this phenomenon. Theoretical design of common springs available with literature has been adapted for our application. A complete design method and an experimental procedure to test a prototype are described for the proposed isolator. Based on this procedure, an experimental study on a complete prototype of the proposed isolator with a load bearing capacity of 400kN. Analysis of the experimental results confirms the good performance of the prototype. A theoretical and numerical model are presented to simulate the dynamic behaviour of the proposed isolator. Finally, an unidirectional and non linear dynamic analysis model is proposed to calculate the design displacement for the bearing. The software is based on the model of a deck isolated by a seismic bearing located at the top of the pier. Another computer program which performs non linear dynamic analysis for three dimensional structures has been modified to incorporate five new structural elements to take in account the behaviour of any seismic bearings in a bridge.