A non-separable stochastic model for pulse-like ground motions

Summary A procedure to generate horizontal pairs of synthetic near‐fault ground motion components for specified earthquake source and site characteristics is presented. Some near‐fault ground motions contain a forward directivity pulse; others do not, even when the conditions for such a pulse are favorable. The proposed procedure generates pulse‐like and non‐pulse‐like motions in appropriate proportions. We use our recent stochastic models of pulse‐like and non‐pulse‐like near‐fault ground motions that are formulated in terms of physically meaningful parameters. The parameters of these models are fitted to databases of recorded pulse‐like and non‐pulse‐like motions. Using these empirical “observations,” predictive relations are developed for the model parameters in terms of the earthquake source and site characteristics (type of faulting, earthquake magnitude, depth to top of rupture plane, source‐to‐site distance, site characteristics, and directivity parameters). The correlation coefficients between the model parameters are also estimated. For a given earthquake scenario, the probability of occurrence of a directivity pulse is first computed; pulse‐like and non‐pulse‐like motions are then simulated according to the predicted proportions using the empirical predictive models. The resulting time series are realistic and reproduce important features of recorded near‐fault ground motions, including the natural variability. Moreover, the statistics of their elastic response spectra agree with those of the NGA‐West2 dataset, with the additional feature of distinguishing between pulse‐like and non‐pulse‐like cases and between forward and backward directivity scenarios. The synthetic motions can be used in addition to or in place of recorded motions in performance‐based earthquake engineering, particularly when recorded motions are scarce.

“…They include source-based deterministic models, 1,17,18 source-based stochastic models, [19][20][21] site-based stochastic models, 4,[22][23][24][25] and hybrid models. They include source-based deterministic models, 1,17,18 source-based stochastic models, [19][20][21] site-based stochastic models, 4,[22][23][24][25] and hybrid models.…”

Section: Introductionmentioning

confidence: 99%

“…They include source-based deterministic models, 1,17,18 source-based stochastic models, [19][20][21] site-based stochastic models, 4,[22][23][24][25] and hybrid models. 24,25 The residual motion is modeled using a source-based [19][20][21] or a sitebased 4,22-25 stochastic model. For engineering applications, stochastic and hybrid ground motion models are generally of more interest because they are able to represent a wider range of the frequencies that are present in recorded ground motions.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Simulation of orthogonal horizontal components of near‐fault ground motion for specified earthquake source and site characteristics

Dabaghi

Kiureghian

2018

“…Recently, to account for the observed variability of the parameters of pulses extracted from near‐fault impulsive records explicitly, few probabilistic models describing the uncertainty of low‐frequency contents in impulsive ground motions were proposed, for example, delta function and BOX or COS power spectrum . However, the energy of these types of power spectral density (PSD) concentrates at the dominant frequency of pulse ω p for a target record.…”

Section: Introductionmentioning

confidence: 99%

A stochastic model and synthesis for near‐fault impulsive ground motions

Yang

Zhou

2014

The orientations of ground motions are paramount when the pulse-like motions and their unfavorable seismic responses are considered. This paper addresses the stochastic modeling and synthesizing of near-fault impulsive ground motions with forward directivity effect taking the orientation of the strongest pulses into account. First, a statistical parametric analysis of velocity time histories in the orientation of the strongest pulse with a specified magnitude and various fault distances is performed. A new stochastic model is established consisting of a velocity pulse model with random parameters and a stochastic approach to synthesize high-frequency velocity time history. The high-frequency velocity history is achieved by integrating a stochastic high-frequency accelerogram, which is generated via the modified K-T spectrum of residual acceleration histories and then modulated by the specific envelope function. Next, the associated parameters of pulse model, envelope function, and power spectral density are estimated by the least-square fitting. Some chosen parameters in the stochastic model of near-fault motions based on correlation analysis are regarded as random variables, which are validated to follow the normal or lognormal distribution. Moreover, the number theoretical method is suggested to select efficiently representative points, for generating artificial near-fault impulsive ground motions with the feature of the strongest pulse, which can be used to the seismic response and reliability analysis of critical structures conveniently. Finally, the simulated ground motions demonstrate that the synthetic ground motions generated by the proposed stochastic model can represent the impulsive characteristic of near-fault ground motions.

A finite element model for seismic response analysis of deformable rocking frames

Vassiliou

Mackie

Stojadinović

2016

Summary A new finite element model to analyze the seismic response of deformable rocking bodies and rocking structures is presented. The model comprises a set of beam elements to represent the rocking body and zero‐length fiber cross‐section elements at the ends of the rocking body to represent the rocking surfaces. The energy dissipation during rocking motion is modeled using a Hilber–Hughes–Taylor numerically dissipative time step integration scheme. The model is verified through correct prediction of the horizontal and vertical displacements of a rigid rocking block and validated against the analytical Housner model solution for the rocking response of rigid bodies subjected to ground motion excitation. The proposed model is augmented by a dissipative model of the ground under the rocking surface to facilitate modeling of the rocking response of deformable bodies and structures. The augmented model is used to compute the overturning and uplift rocking response spectra for a deformable rocking frame structure to symmetric and anti‐symmetric Ricker pulse ground motion excitation. It is found that the deformability of the columns of a rocking frame does not jeopardize its stability under Ricker pulse ground motion excitation. In fact, there are cases where a deformable rocking frame is more stable than its rigid counterpart. Copyright © 2016 John Wiley & Sons, Ltd.