Seismic behaviour of isolated multi-span continuous bridge to nonstationary random seismic excitation

Abstract

This paper concentrates on the results of responses of a multi-span continuous bridge isolated with double concave friction pendulum bearings subjected to non-stationary random seismic excitation characterized by the incoherence, the wave-passage, and the site-response effects. The earthquake excitation is modelled as a non-stationary random process as uniformly modulated broad-band excitation. To perform the seismic isolation procedure, the double concave friction pendulum bearings which are sliding devices that utilize two spherical concave surfaces are placed at each of the six support points of the deck. The non-stationary response of the isolated bridge is compared with the corresponding stationary response in order to study the effects of non-stationary characteristics of the earthquake input motion. Solutions obtained from the stationary and non-stationary stochastic analyses for the isolated bridge to spatially varying earthquake ground motions are compared for the special cases of the earthquake ground motion model. The spatially varying earthquake ground motions are described stochastically based on an empirical coherency loss function and a filtered power spectral density function. The site effect is considered by a transfer function derived from one dimensional wave propagation theory. It is observed that the stationary assump-S. Ates ( ) tion is reasonable for the considered ground motion duration.

Perturbation methods in evolutionary spectral analysis for linear dynamics and equivalent statistical linearization

“…The evolutionary spectral analysis is used to compute the response of a multi-span bridge subject to an earthquake, modeled as a coherent random field [35,72,1].…”

“…The equation of motion [1] since the contribution to the excitation coming from the damping forces may be neglected [30]. The projection of (83) into the modal basis Φ reads ( )…”

Nonstationary First Threshold Crossing Reliability for Linear System Excited by Modulated Gaussian Process

“…Moreover, a wide class of engineering problems deals with reliability evaluation of structures subject to loads characterized by an intrinsic probabilistic nature and whose correct description could be obtained by means of random process. Besides, there are situations where suitable modelling of these loads requires taking their nonstationary characteristics into account [1][2][3][4]. Examples of such conditions include ground acceleration during an earthquake and structural vibration induced by gust loading.…”

Integration Algorithm for Covariance Nonstationary Dynamic Analysis of SDOF Systems Using Equivalent Stochastic Linearization

“…The inner evolutive nature of the input has serious consequences in structural responses, and this has been observed both in general cases, such as Du±ng models, 2 and in real engineering problems, such as buildings or bridges. 13,14 With reference to nonstationary input, a more proper approach consists in using nonseparable input. This produces some numerical di±culties, since the input should be de¯ned by using processes modulated in amplitude and/or in frequency.…”