Search results for "Random vibration"
showing 7 items of 27 documents
Reliability Analysis of Discrete Dynamic Systems under Non-Stationary Random Excitations
1987
In this paper we shall describe an approach to the study the reliability of structures modeled as linear discrete dynamic systems which has been designed to withstand nonstationary random excitations. Ne shall discuss this problem upon consideration the following four steps:
On the sensitivity of bridge seismic response with local soil amplification
1998
The paper presents a numerical sensitivity study of the local site effects on structural response. Following a recently developed model of spatial coherency and a concept of a simple site coefficient the local site effects are modelled as filtrations of excitation processes with a frequency shift. An analysis of a bridge response with supports founded on different soils is carried out. The joint effects of dynamic response and pseudostatic motion are considered. Two types of response are analysed: longitudinal and transverse. The differences between dynamic displacements and force responses are pointed out.
Direct evaluation of the equivalent linear damping for TLCD systems in random vibration for pre-design purposes
2014
Abstract Passive control of structural vibrations has received in recent years a great attention from researchers concerned with vibration control. Several types of devices have been proposed in order to reduce the dynamic responses of different kinds of structural systems. Among them, the Tuned Liquid Column Damper (TLCD) proved to be very effective in reducing vibration of structures. Since the increasing use of TLCDs in practical realizations, this paper aims at developing an approximate formulation, by means of a statistical linearization technique, able to estimate the parameters of a structure equipped with a TLCD subjected to random loads for pre-design purposes. Moreover, it is show…
Frequency composition of traction and tillage forces on a mole plough
1997
Field experiments were carried out in order to quantify the variations of the traction and tillage forces on a mole plough, in the case of four clayey soils of Eastern France. The same tractor-implement system, the same forward working speed (1 m s−1) and the same length of ploughing (20 m) were used. Specially designed strain gauge transducers applied to the system delivered a signal which was numerised and analysed in terms of power spectral density (PSD) function. The frequency composition of the traction and tillage forces consisted of interactions between soil and tool as well as vibrations of the tractor-implement system. Low frequencies (0–2 Hz range) were related to the random prope…
Spatial response spectra and site amplification effects
2002
A simplified analysis of local site amplification effects on the seismic response of multi-support structures is presented. The site effects are modeled by considering reflections and transmission of vertically propagating shear waves from bedrock to the surface through a soil layer. A random vibration-based response spectrum of a simple oscillator on two supports, one of which is founded on rock outcrop and the other on soil layer, is formulated in order to study the influence of non-uniform excitations on multi-support structures. Joint inertial and pseudo-static effects in the overall response are studied in detail. The resulting response spectra are formulated as displacement and force …
Random vibration mitigation of beams via tuned mass dampers with spring inertia effects
2019
The dynamics of beams equipped with tuned mass dampers is of considerable interest in engineering applications. Here, the purpose is to introduce a comprehensive framework to address the stochastic response of the system under stationary and non-stationary loads, considering inertia effects along the spring of every tuned mass damper applied to the beam. For this, the key step is to show that a tuned mass damper with spring inertia effects can be reverted to an equivalent external support, whose reaction force on the beam depends only on the deflection of the attachment point. On this basis, a generalized function approach provides closed analytical expressions for frequency and impulse res…
Stochastic linearization for the response of MDOF systems subjected to external and parametric Gaussian excitations
1991
The stochastic linearization approach is examined for the most general case of non zero-mean response of non-linear MDOF systems subjected to parametric and external Gaussian white excitations. It is shown that, for these systems too, stochastic linearization and Gaussian closure are two equivalent approaches if the former is applied to the coefficients of the Ito differential rule. Moreover, an extension of the Atalik-Utku approach to non zero-mean response systems allows to obtain simple formulations for the linearized drift coefficients. Some applications show the good accuracy of the method.