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Target uniform hazard response spectra. Top: the target UHRS at the rock outcrop and the scaled response spectra for the three seed records. Bottom: the target UHRS and the response spectra of the resulting compatible records.
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The seismic design of most civil structures is usually accomplished using the response spectrum approach or simplified equivalent lateral force methods. However, some special tasks require the use of dynamic time history analyses. In the nuclear industry, for example, dynamic analyses are required in the design verification and seismic assessment o...
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Citations
... More specifically, it employs localized wave-like functions known as wavelets instead of continual harmonics as a base to decompose a signal. Among various WT methodologies for generating artificial ground motions are the wavelet packet transform [23,30], the Discrete Wavelet Transform [15], the Harmonic Wavelet Transform [21,36], and the Continuous Wavelet Transform (CWT) [37]. The choice of an appropriate joint time-frequency signal analysis approach heavily depends on the problem at hand, since different approaches may not yield the same estimate of the energy distribution on the time-frequency plane for the same signal (e.g. ...
A new stochastic methodology is proposed for the generation of bidirectional horizontal components of artificial, fully nonstationary, site‐ and spectrum‐compatible seismic accelerograms through a nonseparable process. The model operates in the time‐frequency domain and combines spectral representation techniques with signal processing tools. The basis of the methodology involves the generation of spectrum‐compatible stationary artificial accelerogram signals whose nonstationarity is then modeled with a time‐frequency modulating function that is based on a seed ground motion record. At the core of the proposed methodology lies the use of the Continuous Wavelet Transform (CWT). Specifically, the CWT method is used to perform time‐frequency analysis and to define the nonstationary component. The proposed methodology provides any required number of seismic accelerograms whose temporal and spectral modulation is consistent with the characteristics of the site of interest. Furthermore, the model is extended to the case of pairs of bidirectional horizontal components. This is accomplished by probabilistically generating two orthogonal spectra whose geometric mean spectrum is compatible with a target spectrum. This procedure also takes into account the correlation structure of spectral acceleration pairs in orthogonal directions at different periods based on empirical models. The bidirectional components are then generated with the proposed site and spectrum‐based methodology. An online tool that implements the proposed methodology is freely provided.
... In this context, V and ζ are set to π and 0.05, respectively. The scale "s" and shift "p" of the wavelets, with s ¼ 2π VT and p ¼ discretized time step, are adopted for such applications, following the methodology outlined in the past research (Montejo and Suarez, 2013). ...
This study addresses the critical need to understand the seismic behavior of cable-stayed bridges under Multi-Support Excitation (MSE) in order to mitigate earthquake-induced damage to these structures. The primary focus is on the investigation of response amplification phenomena and their seismic implications for cable-stayed bridges. Through a detailed comparative analysis of MSE and Synchronous Excitation (SE) across various structural locations, the study evaluates the impact of site-specific recorded ground motions of different earthquake categories. A pragmatic framework is developed to simulate realistic MSE ground motions for diverse earthquake scenarios, emphasizing the necessity of considering MSE in bridge design. The findings reveal a significant amplification of the design requirements due to antisymmetric mode excitation and increased tower and pier motions. The study also identified the need for in-depth analysis of cable-stayed bridges to address the increased vulnerability of tower-adjacent areas and to devise targeted reinforcement strategies of vulnerable components. These insights are critical for advancing seismic design practices and improving the resilience of cable-stayed bridges, contributing to safer urban infrastructure.
... where K ψ represents a constant depends on the wavelet function selected for the analysis [44]. ...
... Step 4: The response spectrum of the generated GM is then compared with the target response spectrum, and Steps 1-3 are repeated until the desired level of matching is obtained (the Root-Mean-Square of the differences in percent at each of the periods was less than 6 % [43]) or the maximum number of iterations is reached (usually 30). The details of this methodology can be found in Montejo et al. [44]. It should be noted that another spectrum-compatible methods [41,45] can be adopted into the proposed framework. ...
Rapid seismic-damage assessment of buildings on a regional scale is of considerable significance for emergency response and recovery endeavors following earthquakes. Deep-learning methods provide a critical means for rapid seismic-damage assessment. However, this method faces the challenge of insufficient ground motion (GM) samples with high destructive power owing to the limited availability of strong GM data. To address this issue, a rapid seismic-damage assessment method for buildings on a regional scale based on spectrum-compatible data augmentation and deep learning is proposed. First, the continuous wavelet transform (CWT) method is used to construct a response-spectrum-compatible GM for augmenting strong-motion data. The augmented strong-motion database is then employed in conjunction with deep-learning algorithms to predict building damage in urban areas. The proposed method is illustrated through an analysis of individual building cases and regional scenarios. A comparative study is also conducted by comparing the proposed method with the widely used acceleration-amplitude-scaling-based data-augmentation method. The main conclusions are as follows. (1) The GM generated by the proposed data-augmentation method exhibits a smaller degree of dispersion in terms of duration and seismic responses for individual buildings and building clusters compared to those of the acceleration-amplitude-scaling-based data-augmentation method. (2) The proposed spectrum-compatible GM data-augmentation method demonstrates improved accuracy in deep-learning predictions, surpassing the traditional amplitude-scaling-based data-augmentation method. These results highlight the significance of employing the proposed GM data-augmentation method for deep-learning-based seismic-damage assessment. (3) The proposed method achieves a seismic-damage assessment accuracy of 87.4% in a computation time of less than 1 s, resulting in a remarkable 1000-fold improvement in efficiency compared with time-history analysis method, which effectively fulfills the requirements for rapid post-earthquake emergency assessments of building clusters in a region.
... where K ψ represents a constant depends on the wavelet function selected for the analysis [44]. ...
... Step 4: The response spectrum of the generated GM is then compared with the target response spectrum, and Steps 1-3 are repeated until the desired level of matching is obtained (the Root-Mean-Square of the differences in percent at each of the periods was less than 6 % [43]) or the maximum number of iterations is reached (usually 30). The details of this methodology can be found in Montejo et al. [44]. It should be noted that another spectrum-compatible methods [41,45] can be adopted into the proposed framework. ...
Hospitals play an important role in post-earthquake emergency response and recovery, and the assessment of post-earthquake medical functionality is important for ensuring hospital functionality after earthquakes. Such assessments of hospital departments currently face the following challenges: (1) lack of unified modeling rules and integrated platforms to manage the associated data; (2) the complex functional coupling relationships between different components and medical equipment are not often considered; (3) lack of unified communication platforms, which hinders collaboration among researchers from different fields. Therefore, this paper proposes a BIM-based method for post-earthquake medical functionality assessment (PEMFA) of hospital departments considering functional coupling. Specifically, first, multi-level of detail (LOD) BIM modeling rules for structural components, nonstructural components, and medical equipment oriented towards PEMFA are suggested. Thereafter, a conversion method for the medical functionality assessment model and PEMFA method based on BIM are proposed. Subsequently, the PEMFA method for departments is proposed, emphasizing functional coupling. Finally, a typical medical building is selected as an example to demonstrate the proposed method. The results indicate the following: (1) the fragility data for various components and equipment of medical buildings can be integrated using the proposed multi-LOD modeling rules; (2) the mapping relationship between medical functional logic and BIM has been established, through which the functional coupling relationship between different components and equipment can be fully considered, thus providing an important method for the PEMFA of hospital departments and displaying results.
... As the acceleration response spectra of target LPGMs and ordinary ground motion are determined in Section 2.2, the spectra-compatible time histories of ground motions can be generated via a CWT-based algorithm proposed by Montejo et al. [27]. A brief introduction of this adopted algorithm is given below with Eqs. ...
... A brief introduction of this adopted algorithm is given below with Eqs. (2)(3)(4)(5) [27]. ...
... where K Ψ is a constant related to Ψ [27]. The acceleration response spectrum of G(t) is then compared with the target spectrum, and Eqs. ...
Super high-rise buildings usually exhibit low fundamental frequencies and are particularly susceptible to Long Period Ground Motions (LPGMs) characterized by rich components in long-period range. Previous seismic analyses of super high-rise buildings have primarily considered ordinary earthquake actions, overlooking the influence of LPGMs. To address this gap, the seismic responses of super high-rise buildings ranging in height from 400 m to 800 m are investigated when subjected to LPGMs. The effectiveness of earthquake intensity measures, which serve as indices connecting seismic hazards to structural responses, is evaluated in capturing the seismic effects caused by LPGM excitations. Firstly, this study introduces a statistical model for the response spectra of LPGMs. A simulation algorithm utilizing Continuous Wavelet Transformation (CWT) is then employed to generate LPGMs. Subsequently, simplified shear-flexural models are applied to serve as computational models for super high-rise buildings with varying heights. Furthermore, this study calculates, analyzes and compares typical seismic responses, such as lateral displacements and inter-story drifts, of these super high-rise buildings under simulated LPGMs and ordinary earthquake excitations. Additionally, a set of seismological ground motions is utilized to validate the seismic response analysis. The findings of this study reveal that LPGMs lead to significantly larger responses of super high-rise buildings exceeding 400 m in height compared to ordinary earthquakes. Furthermore, this study examines the correlation coefficients between various existing earthquake intensity measures and seismic responses under LPGM excitations. The results indicate a strong relationship between the LPGM induced responses and the spectral acceleration and velocity at the fundamental periods of the structures. The aim of this paper is to explore the seismic response of super high-rise buildings under LPGMs and provide a scientific basis for their seismic analysis and design.
... This set is constructed using the conventional spectral matching approach, where each horizontal component is independently matched to the target RotD100 spectrum. The spectral matching was performed using the CWT (Continuous Wavelet Transform) based algorithm proposed in [17] and implemented in the Python module REQPY [18]. As seen on the middle row plots in Figure 2, while there is a tight match for each horizontal component response spectrum, the resulting RotD100 may greatly exceed the target. ...
This article evaluates two different approaches to generate pulse‐like spectrally matched earthquake records pairs compatible with a target RotD100 spectrum. One is the conventional approach of separately matching each horizontal component to the target RotD100 spectrum, the other approach simultaneously modifies both horizontal components to tightly match the target RotD100. The characteristics of the resulting records are evaluated using amplitude scaled pulse records as baseline for comparison. It is shown that, using a target spectrum that includes a narrow‐band modification to accommodate the presence of a pulse, largely increases both methodologies likelihood of generating spectrally matched records that preserve the pulse‐like nature of the seeds. However, the records generated through independent component matching exhibit RotD100 spectral amplitudes that largely surpass the target amplitudes, and instantaneous power (IP) and peak ground velocities (PGV) substantially larger than the observed for the amplitude scaled records. Consequently, these motions generated unrealistically large inelastic demands when used as input for nonlinear response history analyses (NRHA), with mean peak inelastic demands up to 60% larger than the expected from amplitude scaled records. Conversely, the approach based on simultaneous modification of the two horizontal components generated the largest number of successful matches and the resulting records exhibited IP and PGV values close to the obtained for the amplitude scaled records. When used as input for NRHA, the mean peak inelastic demands were very close to the demands imposed by the amplitude scaled set. These results suggest that current 10% spectral amplitude penalization for spectrally matched records in ASCE7 is unnecessary for pulse‐like motions.
... The spectral matching was performed using the Python module REQPY (Montejo, 2021a) which contains different functions implementing CWT (Continuous Wavelet Transform) based algorithms (e.g. Montejo and Suarez 2013). The most naïve approach is to match each horizontal component separately to the target RotD100 spectrum, this set is denoted as sep.match. ...
... where Ts is the sampling time and is the number of recorded samples of s(t);a is the scale factor;b ¼ iTs is a time-shifting factor, being an integer value; w (a,b) Ã is the complex conjugate of the daughter wavelet w, which is a time translated and scale expanded/compressed version of a finite energy function w (t), called a mother wavelet. The Fast Fourier Transform (FFT) algorithms combined with CWT reduces computation burden and aids in noise elimination [41,42]. The Fourier transform-based CWT (FTCWT) [14] is represented as an inverse Fourier transform, given in Eq. (3), a convolution of the signal Fourier transforms, and wavelet Fourier transforms. ...
Fault diagnosis is essential to attain the microgrid’s stable, reliable, and economical operation. However, a microgrid’s fault current varies drastically based on the connected operating mode and connected renewable energy sources. This paper develops an intelligent fault detection and identification scheme for microgrids with high renewable energy penetration by combining Fourier-based Continuous Wavelet Transform (FTCWT) and Deep Learning (DL) methods. Several time-domain case studies representing different microgrid operating conditions were obtained and pre-processed in MATLAB/SIMULINK. The time-series data at the relay location are processed using an FTCWT to get time-frequency representation, and the sequence components waveforms were computed. The time-frequency representation and sequence components waveform contain helpful information, including fault conditions and healthy operating conditions for grid-connected and islanded microgrids that act as input datasets to the DL models. The proposed DL models perform fault location identification, fault type identification, and fault phase-detection for different operating modes. The development of the DL model for the fault detection/classification unit and fault location identification unit is carried out in the PyTorch framework. The experimental results show that the proposed model is more accurate when compared to the state-of-the-art methods.
... This method fully considers the local site characteristics and avoids the problem of phase difference in response to different borehole points when time history interpolation is directly carried out. The main steps of seismic wave correction by continuous wavelet transform are as follows [39] : ...
As the hub of the traffic network, the rapid assessment of the damaged state of bridges after earthquakes is of great significance for post-disaster rescue. The traditional vulnerability-based method can only provide the probability of different damage states of structures under different earthquake intensity indicators, which confuses the selection of post-disaster rescue routes. Therefore, based on nonlinear dynamic time history response analysis, this paper proposes a technology for earthquake disaster simulation of regional bridge groups and rapid assessment of post-earthquake damage state. First, the surface seismic response is calculated based on the regional geological borehole data obtained from the previous investigation; Second, the simplified computational mechanical model of the regional girder bridge is extracted to achieve standardized and modular data input and response analysis; Finally, the damaged state of the bridge is evaluated quantitatively based on the selected component damage index. Eighty-five bridges in a specific area are considered an example to verify the proposed method. The results show that the proposed method has high calculation efficiency and can consider the site characteristics and structural design parameters. Also, the calculation results can better reflect the actual earthquake damage distribution, providing strong technical support for post-disaster rescue.
... This approach is effective, although the frequency aspect of the adjustment is unclear, especially for cases where the relation between the scale and frequency for some wavelets is not uniquely defined [17,18]. In other studies [25][26][27][28], it is considered that the record can be decomposed into a set of coefficients that are associated with a set of functions of time. The coefficients are then adjusted iteratively to obtain the spectrum-matched record. ...
Spectrum-matched records are used in seismic engineering applications. The available approaches in the literature are based on the Fourier transform or wavelet transform. In the present study, we propose a novel and easy-to-implement approach to generate spectrum-matched records for a given seed record. The approach is based on the S-transform (ST). The use of the transform is advantageous since they provide refined time-frequency decomposition. The approach adjusts the amplitude of the ST coefficients in the S-transform domain. The approach is effective in matching a prescribed response spectrum at specified frequencies without complex parameter adjustment. The spectrum-matched records qualitatively retain the look of the seed records. The spectral acceleration of the spectrum-matched records is equal to the target spectrum at the specified frequencies, where the matching is required and specified.
