Inelastic buckling mode interactions and resonance instabilities in thin-walled columns due to the fatigue damage

Abstract

Purpose The problems of inelastic instability (buckling) and dynamic instability (resonance) have been the subject of extensive investigation and have received wide attention from the structural mechanics community. This paper aims to tackle these problems in thin-walled structures, taking into account geometrical and/or material non-linearity. Design/methodology/approach The inelastic buckling mode interactions and resonance instabilities of prismatic thin-walled columns are analysed by implementing the semi-analytical finite strip method (FSM). A scalar damage parameter is implemented in conjunction with a material modelling named rheological-dynamical analogy to address stiffness reduction induced by the fatigue damage. Findings Inelastic buckling stresses lag behind the elastic buckling stresses across all modes, which is a consequence of the viscoelastic behaviour of materials. Because of the lag, the same column length does not always correspond to the same mode at the elastic and inelastic critical stress. Originality/value This paper presents the influence of mode interactions on the effective stresses and resonance instabilities in thin-walled columns due to the fatigue damage. These mode interactions have a great influence on damage variables because of the fatigue and effective stresses around mode transitions. In its usual semi-analytical form, the FSM cannot be used to solve the mode interaction problem explained in this paper, because this technique ignores the important influence of interaction of the buckling modes when applied only for undamaged state of structure

Fatigue damage in bending of reinforced concrete frames using non-destructive tests for dynamic strength of the cylinder

“…Time-dependent material behavior, i.e. viscoelasticity (VE) and/or viscoplasticity (VP), may lead to instabilities of structures that do not develop suddenly, but over a long period of time, which may be predicted by the fundamental (lowest) frequency (Mila sinovi c et al, 2020b). The RDA is an analytical method whereby resonance frequencies may be simply calculated using the modal damping ratios equal to zero.…”

Rheological-dynamical model of concrete and its application on RC beams

“…The RDA solves quasi-static problems using limit values of dynamic expressions from theory of fatigue, at zero excitation frequency. As a complete example, the inelastic buckling mode interactions and resonance instabilities of prismatic thin-walled columns induced by fatigue damage were also solved using the RDA (Milašinović et al 2020).…”