Simulation of spatially varying ground motions including incoherence, wave‐passage and differential site‐response effects

Abstract

SUMMARYA method is presented for simulating arrays of spatially varying ground motions, incorporating the effects of incoherence, wave passage, and differential site response. Non-stationarity is accounted for by considering the motions as consisting of stationary segments. Two approaches are developed. In the first, simulated motions are consistent with the power spectral densities of a segmented recorded motion and are characterized by uniform variability at all locations. Uniform variability in the array of ground motions is essential when synthetic motions are used for statistical analysis of the response of multiply-supported structures. In the second approach, simulated motions are conditioned on the segmented record itself and exhibit increasing variance with distance from the site of the observation. For both approaches, example simulated motions are presented for an existing bridge model employing two alternatives for modeling the local soil response: i) idealizing each soil-column as a single-degree-of-freedom oscillator, and ii) employing the theory of vertical wave propagation in a single soil layer over bedrock. The selection of parameters in the simulation procedure and their effects on the characteristics of the generated motions are discussed. The method is validated by comparing statistical characteristics of the synthetic motions with target theoretical models. Response spectra of the simulated motions at each support are also examined.

Simulation of Spatially Varying Ground Motions in V-shaped Symmetric Canyons

“…Seismic ground motions in general have non-stationary characteristic in both time and frequency domains. However, most ground motions can be approximated with temporal segments that are nearly stationary [Konakli and Der Kiureghian, 2012]. For this reason, the case of stationary processes is studied herein.…”

“…Shinozuka and Zhang [1996] pointed out that the two techniques (MLP and CPDF) were stochastically equivalent, in spite of the different approaches they utilized to generate the unknown Fourier coefficients. Konakli and Der Kiureghian [2012] used both the conditional simulation and unconditional simulation to simulate spatially varying ground motions accounting for incoherence, wave-passage and differential site-response effects.…”

Excitación sísmica asíncrona en puentes: patrones de asincronismo, métodos de análisis y tipologías estudiadas

“…This material could be implemented in the asynchronous analysis (Soyluk and Dumanoglu, 2004) 99 taking into account the wave passage effect. It is about assigning an accelerogram to every structure support temporarily displacing it in the direction of the wave attack (Valdebenito and Aparicio, 2005) (Álvarez et al, 2012) (Konakli and Der Kiureghian, 2012). The method extends to nonlinear analysis according to (Ghobarah et al, 1996) and (Álvarez et al, 2006), this method is not very elaborate if it is compared with the method described in point 5.1 and its main disadvantage resides in not including the other asynchronous patterns.…”

Anti-symmetric mode excitation and seismic response of base-isolated bridges under asynchronous input motion

“…On the other hand, simulation of non-synchronous ground motions in time history analysis is a more straightforward option for the calculation of the structural (linear or not) response in a Monte Carlo framework. In this context, numerous simulation techniques have been developed for the generation of spatially variable ground motions; these either describe the random field through the combination of a power spectral density (PSD) model with a coherency one, or they simulate them conditioned to "known" accelerograms [11,12]. Spectral representation is one of the most popular methods for the simulation of random fields [13,14].…”