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Opis przemieszczeń niesprężystych w symulacji zużycia za pomocą modelu ciała Prandtla

Piotrowski J.

Zeszyty Naukowe. Transport / Politechnika Śląska

2004

z. 54

109-118

Do opisu normalnych przemieszczeń niesprężystych w symulacji zużycia zaproponowano heurystyczny model warstwy wierzchniej koła i szyny w postaci ciała Prandtla, przytwierdzonego do sprężystego materiału rodzimego. Przemieszczenia ciała mogą być niesprężyste. W praktyce symulacji zużycia będzie to prowadzić do modyfikacji profili nie tylko przez ścierny ubytek materiału, lecz także wskutek resztkowych przemieszczeń niesprężystych. Przedstawiono metodę rozwiązywania normalnego zadania kontaktowego z uwzględnieniem warstwy wierzchniej według proponowanego modelu. Praca zawiera przykłady obliczeniowe. Wyznaczenie parametrów modelu wymaga użycia MES.

In order to take into account normal inelastic displacements during wear simulation a heuristic model of the surface layer has been proposed in the form of the Prandtl body fixed to the elastic material. The displacements of the Prandtl body may be inelastic. In practise of wear simulation this will lead to the modification of profiles not only by abrasive loss of material but also by inelastic, residual displacements. The method of solving the normal contact problem for bodies with the layer model has been presented. The paper presents numerical results. Determination of parameters of the body requires FEM calculations.

Effect of strength and stiffness deterioration on seismic behaviour of R/C asymmetric buildings

Das P. K., Dutta S.C.

International Journal of Applied Mechanics and Engineering

2002

Vol. 7, no 2

527-564

Past earthquakes (e.g., 1985 Mexico earthquake) have demonstrated the severe seismic vulnerability of asymmetric buildings due to coupled lateral-torsional vibration in elastic as well as in inelastic range, even under a purely translational ground shaking. Extensive research effort on inelastic behaviour of asymmetric buildings has generally used an elasto-plastic or bilinear hysteresis behaviour for the structural load-resisting elements, ignoring the strength and stiffness deteriorating characteristics of RC structural elements under cyclic loading. Hence, these studies could not recognize the possibility of progressively increasing torsional damage of load resisting elements near one edge, due to continuous shifting of centre of resistance caused by such degradations during inelastic excursions. The present study on asymmetric one storey building systems aims to assess these possible detrimental effects. The system responses are studied using a) elasto-plastic, b) stiffness degrading, c) strength deteriorating, and d) stiffness degrading as well as strength deteriorating hysteresis models for the load-resisting elements. These responses are expressed in terms of the maximum displacement demand and hysteretic energy demand in load-resisting elements. Variations of these two response quantities are studied for feasible ranges of influencing parameters due to each of the four hysteresis behaviours. The results are compared to understand the effects of stiffness degradation and strength deterioration. The remedial measures are also outlined to control the excessive response found to be generated due to such degradation effects. The study may prove useful to arrive at more justified torsional code provisions.