טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentZeiger Dror
SubjectInelastic Non-Linear Dynamic Behavior of Cable-Stayed
Bridges
DepartmentDepartment of Civil and Environmental Engineering
Supervisor Professor Emeritus Yeoshua Frostig


Abstract

          The effect of cable yielding and cable loosening on the behaviour of cable-stayed bridges subjected to dynamic loadings is studied in this dissertation.

The widely used method to deal with the periodic wind loads such as vortex shedding and flutter consists of determining the critical wind speed that results in flutter or resonance in the case of vortex shedding. The safety factor determined is the ratio between the critical and the maximum wind speed predicted in the site. The method presented in this research allows to determinate the safety factors for the structural components in terms of stress or strain level.

A lot of research works, only take into account the geometric nonlinearity, while neglecting the material nonlinearity. In this work, the response of the structure is studied considering of the material nonlinearity of the cables.

A nonlinear finite element method, based on incremental analysis, has been developed to provide an analytical tool for the investigation.

Basic characteristics of the nonlinear response are studied, using few examples. The results show that material nonlinearity plays a significant role in the dynamic response of such bridges. On the one hand, yielding or slacking of cables lead to a considerable increase in deformations, but on the other yielding results in an additional damping. Geometric nonlinearity becomes significant only when material nonlinearity is considered.

Safety factors are obtained also for cases in which the linear analysis yields an infinite increase in the displacements and stresses, hence providing a clearer view on the safety of the bridge.