Ground Motion Scaling Research Articles

Estimation of Earthquake-Induced Direct Economic Losses of Portfolio Buildings Based on Seismic Fragility Surface

Regional seismic loss assessment is crucial for developing earthquake emergency plans, which can significantly reduce casualties and socioeconomic losses in urban communities. Due to the complex types of building structures in a region, it is not possible to accurately measure the damage state of building structures using a single scalar ground motion intensity measure (IM). To more accurately reflect the responses of structures under earthquake excitations, the seismic fragility surface models for 4 typical RC frame structures are developed based on the vector ground motion IMs. The results indicate that the fragility surface model offers a superior level of precision in capturing the inherent uncertainty of ground motion and subsequently determines a more precise probability of structural failure, outperforming traditional single scalar ground motion IM fragility curve models. This enhanced accuracy holds significant implications for regional loss assessment. To fully consider the spatial cross-correlation of vector ground motion IMs, based on the established ground motion database of 8778 records, principal component analysis (PCA) and geostatistical analysis methods are used to construct a spatial cross-correlation influence field that simultaneously considers multiple ground motion IMs to simulate more realistic earthquake scenarios. Considering the impact of uncertainty in loss ratio on earthquake-induced direct economic loss estimation results, the maximum entropy technique is used in conjunction with an improved Latin Hypercube Sampling (LHS) to achieve spatially uniform sampling of loss ratio (LR). This study proposes an assessment framework for regional seismic direct economic loss for portfolio buildings based on the seismic fragility surface model considering spatial cross-correlation and uncertainty of loss ratio. The proposed framework is verified by numerical examples, and it is proven that the regional portfolio buildings considering multiple ground motion IMs is more reliable and robust than those merely considering a single ground motion IM, and when spatial cross-correlation is not considered, the probability of serious economic losses will be underestimated.

Seismic Performance Prediction of RC, BRB and SDOF Structures Using Deep Learning and the Intensity Measure INp

The motivation for using artificial neural networks in this study stems from their computational efficiency and ability to model complex, high-level abstractions. Deep learning models were utilized to predict the structural responses of reinforced concrete (RC) buildings subjected to earthquakes. For this aim, the dataset for training and evaluation was derived from complex computational dynamic analyses, which involved scaling real ground motion records at different intensity levels (spectral acceleration Sa(T1) and the recently proposed INp). The results, specifically the maximum interstory drifts, were characterized for the output neurons in terms of their corresponding statistical parameters: mean, median, and standard deviation; while two input variables (fundamental period and earthquake intensity) were used in the neural networks to represent buildings and seismic risk. To validate deep learning as a robust tool for seismic predesign and rapid estimation, a prediction model was developed to assess the seismic performance of a complex RC building with buckling restrained braces (RC-BRBs). Additionally, other deep learning models were explored to predict ductility and hysteretic energy in nonlinear single degree of freedom (SDOF) systems. The findings demonstrated that increasing the number of hidden layers generally reduces prediction error, although an excessive number can lead to overfitting.

Application of Metaheuristic Algorithms in Ground Motion Selection and Scaling for Time History Analysis of Structures

Application of Metaheuristic Algorithms in Ground Motion Selection and Scaling for Time History Analysis of Structures

Assessing the Impact of Ground Motion Duration on Losses in Typical Modern Steel Moment Frames

This research was undertaken to study the duration effects on the seismic economic risk of steel moment frame (SMF) buildings, a prominent class of buildings in commercial stock. Firstly, a modified version of FEMA P-695 ground motion scaling, tailored for seismic loss estimation purposes and incorporating two sets of spectrally matched bi-directional short- and long-duration ground motions, is proposed to study code-compliant plan-symmetrical SMFs with different heights (i.e., two to 20 stories). It is shown that long-duration ground motions increase the collapse risk of SMFs, on average, by 28.0% at the MCE level. Next, a component-based loss estimation methodology was adopted for evaluating the seismic losses under each set of ground motions. These losses are studied separately for building components (i.e., structural and nonstructural) and contents. Moreover, we propose an approach for calculating average annualized loss (AAL) as a prominent risk meter that segregates contributions of short- and long-duration ground motions to attain hazard consistency. Loss analyses showed the minimal impact of building height on the contribution of these two types of earthquakes. The seismic risk analysis of buildings also revealed that collapse risk is influenced mainly by duration effects followed by building and content losses.

Optimal selection and scaling of ground motion records compatible with input energy and acceleration spectra

AbstractNonlinear response history analysis is the primary tool for risk‐targeted design and seismic performance evaluation of structures. These analyses require the selection of a set of ground motions that satisfy predetermined conditions such as spectral acceleration. Numerous efforts have been made so far to obtain ground motion records which are expected to represent possible earthquakes. Even though spectral acceleration‐based ground motion scaling is a common procedure, recent studies showed that structural response can be better represented through the energy content of the records. To this end, this study aims to develop an energy and acceleration spectra‐compatible record selection and scaling methodology to achieve higher efficiency and lower bias in the predicted structural response. The efficiency of the proposed method is evaluated through the standard deviations of the computed story drifts of benchmark structures resulting from the records processed by either the proposed or commonly used methods. The results demonstrated that considering input energy together with spectral acceleration for the selection and scaling of the records can considerably reduce the bias in structural response, especially for structures located on stiff soils.

Broadband Ground-Motion Synthesis via Generative Adversarial Neural Operators: Development and Validation

ABSTRACT We present a data-driven framework for ground-motion synthesis that generates three-component acceleration time histories conditioned on moment magnitude (M), rupture distance (Rrup), time-average shear-wave velocity at the top 30 m (VS30), and style of faulting. We use a Generative Adversarial Neural Operator (GANO)—a resolution invariant architecture that guarantees model training independent of the data sampling frequency. We first present the conditional ground-motion synthesis algorithm (cGM-GANO) and discuss its advantages compared to the previous work. We next train cGM-GANO on simulated ground motions generated by the Southern California Earthquake Center Broadband Platform (BBP) and on recorded the Kiban–Kyoshin network (KiK-net) data, and show that the model can learn the overall magnitude, distance, and VS30 scaling of effective amplitude spectra (EAS) ordinates and pseudospectral accelerations (PSA). Results specifically show that cGM-GANO produces consistent median scaling with the training data for the corresponding tectonic environments over a wide range of frequencies for scenarios with sufficient data coverage. For the BBP dataset, cGM-GANO cannot learn the ground-motion scaling of the stochastic frequency components (f > 1 Hz); for the KiK-net dataset, the largest misfit is observed at short distances (Rrup<50 km) and for soft-soil conditions (VS30<200 m/s) due to the scarcity of such data. Except for these conditions, the aleatory variability of EAS and PSA are captured reasonably well. Finally, cGM-GANO produces similar median scaling to traditional ground-motion models (GMMs) for frequencies greater than 1 Hz for both PSA and EAS but underestimates the aleatory variability of EAS. Discrepancies in the comparisons between the synthetic ground motions and GMMs are attributed to inconsistencies between the training dataset and the datasets used in GMM development. Our pilot study demonstrates GANO’s potential for efficient synthesis of broadband ground motions.

Performance evaluation of concentrically braced frames equipped with pure bending yielding damper

In this paper, the seismic performance of steel concentrically braced frames (CBFs) equipped with the newly proposed pure bending yielding (PBY) damper is examined. The PBY damper, developed by the second author and his co-worker, is a type of steel damper that converts axial force to pure bending in a concentric brace. This is done through steel plates installed perpendicular to the brace axis that are resting on rollers placed symmetrically to produce four-point bending. For the sake of evaluation, 4, 8, and 12-story buildings composed of CBFs are studied. Results of experiments on the same damper are used for verification. The pushover analysis of the CBF systems shows that the systems equipped with the proposed damper are superior to the special concentric braced frames regarding ductility and stability in the nonlinear area of behavior. Besides, nonlinear dynamic analysis under 11 consistent and scaled ground motions exhibits that the residual drifts of the proposed system are less than 1% which is small enough to save nonstructural elements. All of the other structural elements, except for the PBY dampers, are shown to remain in the elastic region free of any seismic damage that confirms the suitable seismic behavior of the system.

Permissible Scale Factors for Various Intensity Measures in Aftershock Ground Motion Scaling

This manuscript investigates the bias introduced by scaling aftershock ground motions when evaluating the performance of structures subjected to earthquake sequences. The study focuses on different hysteretic behaviors exhibited by structures and selects eight intensity measures as scale indicators. A benchmark database comprising 274 recorded mainshock–aftershock ground motions is utilized for analysis. The findings reveal that scaling aftershock records using intensity measures such as SI (seismic intensity), PGV (peak ground velocity), IC (Arias intensity), and Sa (spectral acceleration) relative to mainshock records effectively controls the mean bias within 30% throughout the entire period range, given a maximum scale factor of 10.0. However, it is observed that the additional damage in systems exhibiting un-degrading hysteretic behavior is more significantly affected by aftershock ground motion scaling compared to systems with degrading hysteretic behavior. Furthermore, scaling aftershock ground motions upwards using relative Sa tends to overestimate the additional damage incurred by structures. These results emphasize the importance of considering the specific hysteretic behavior of structures when applying aftershock ground motion scaling, as well as selecting appropriate intensity measures for accurate evaluation of structural performance.

Scaling of earthquake ground motions for tri-directional nonlinear response history analyses of reinforced concrete rectangular bridge piers

In performance-based earthquake design (PBED), both the capacity of the structure and the demand from earthquake ground shaking are required to establish the desired performance levels. A range of possible demands can be estimated through nonlinear response history analyses (NRHA), which requires a suite of earthquake ground motions appropriately scaled to the target earthquake intensity for which the structure's performance is to be evaluated. The scaling is usually done for a particular earthquake intensity measure (IM) to get the associated dispersion in the engineering demand parameter (EDP). Several scaling strategies are available for uni-directional (Uni-NRHA) and bi-directional nonlinear response history analyses (Bi-NRHA). However, for tri-directional nonlinear response history analysis (Tri-NRHA), one literature suggests using the same scale factor (SF) for the vertical component, which is estimated for the Bi-NRHA. Therefore, in this study, three well-known scaling strategies, which are usually used for Uni-NRHA, are employed with 16 different methods for application in Tri-NRHA of a reinforced concrete (RC) single-column bridge pier modelled as a single-mass three-degree-of-freedom (3DoF) system. The absolute maximum drift is taken as the EDP, and a total of 1920 Tri-NRHA of the pier are performed using two suites of 20 far-fault and 20 near-fault ground motions, which are scaled to three levels of target earthquake intensity. The sufficiency and efficiency of all the scaling methods are checked statistically under all three target intensities. The study reports the effects of (i) vertical components in calculating the SF, (ii) earthquake intensity and structural nonlinearity, and (iii) far-fault and near-fault ground motion characteristics on the dispersion of the EDP. Out of 16 scaling methods, one is found to be acceptably efficient than the others for application in Tri-NRHA under both far-fault and near-fault ground motions at all target intensities.

Evaluation the effect of amplitude scaling of real ground motions on seismic demands accounting different structural characteristics and soil classes

Evaluation the effect of amplitude scaling of real ground motions on seismic demands accounting different structural characteristics and soil classes

Seismic response of multi-storied building with shear wall considering soil-structure interaction in Patna, India

The structural response of a building on soft or loose soil differs from that on hard and rocky soil. Investigating the behaviour of buildings with shear walls on such soft soil is essential. This study considers four structural models of the nine-storied building with and without infill walls. The modelled buildings represent the existing buildings in the Patna, India region. The frame was analysed in four different conditions: (1) Fixed base bare frame building, (2) Flexible base bare frame building, (3) Fixed base building with shear walls (4) Flexible base building with shear walls. Twenty-four pairs of scaled ground motion from the PEER Ground Motion Database were selected, and a nonlinear time history analysis was performed in SAP2000v20.0. Understanding that soil-structure interaction is paramount for building on soft soil, the study quantified the seismic response for the building in the Patna region, a region of high seismicity.Moreover, in current scenarios, multistorey buildings with an open ground storey and shear walls are prevalently found owing to their advantage for parking and enhancing the seismic capacity. The result shows that base flexibility significantly increases the peak floor displacement, total floor acceleration, inter-storey drift and displacement ductility for bare frame structures. At the same time, consideration of shear and infill walls only affects the flexible base structures. While shear and infill walls significantly affect the seismic behaviour of the fixed base structure. It was also found that the shear and infill walls increase the structure’s stiffness and thus reduce the fundamental vibration period of the structure. The study’s significant findings are (1) the shear and infill wall significantly reduces the seismic responses of the building, (2) base flexibility (SSI) increases the seismic vulnerability of the buildings, (3) the displacement ductility significantly depends on the aspect ratio (height/width) of the building, and (4) the inter-storey drift is relatively higher in the lower and mid storey of buildings.

Seismic design parameters (R, Cd, and Ω0) for uncoupled composite plate shear walls−concrete filled (C‐PSW/CF)

AbstractComposite Plate Shear Walls−Concrete Filled (C‐PSW/CF) are an innovative seismic force resisting system recently adapted for building applications. The walls consist of parallel steel faceplates connected with tie bars and filled with concrete. This paper summarizes the results of a recent FEMA P695 study completed to verify seismic design parameters for uncoupled C‐PSW/CFs with rectangular flange plate boundary elements. Seven archetype structures were: (i) designed, (ii) modeled using a benchmarked fiber‐based finite element analysis approach, (iii) subjected to nonlinear pushover analysis, (iv) and to incremental nonlinear dynamic analysis to failure for 22‐sets of scaled ground motions, and (v) the results were statistically analyzed to assess performance. These structures ranged from three (3) to twenty‐two (22) stories and included both planar and C‐shaped configurations. As part of this design process, recommendations for stiffness approximations for linear analysis of C‐PSW/CFs were developed. Additionally, these nonlinear incremental dynamic analysis results were post‐processed to determine the rotation and strain demands at the base of these structures at the design basis, maximum considered, and failure level earthquakes. These results showed that the rotation and strain demand at failure level earthquakes were comparable regardless of the ground motion. Ultimately, this FEMA P695 approach verified the R factor of 6.5, Cd factor of 5.5, and Ω0 of 2.5 for C‐PSW/CFs with boundary elements.

EESD special issue: AI and data‐driven methods in earthquake engineering – (Part 1)

EESD special issue: AI and data‐driven methods in earthquake engineering – (Part 1)

Induced Earthquake Source Parameters, Attenuation, and Site Effects From Waveform Envelopes in the Fennoscandian Shield

AbstractWe analyze envelopes of 233 and 22 ML0.0 to ML1.8 earthquakes induced by two geothermal stimulations in the Helsinki, Finland, metropolitan area. We separate source spectra and site terms and determine intrinsic attenuation and the scattering strength of shear waves in the 3–200 Hz frequency range using radiative transfer based synthetic envelopes. Displacement spectra yield scaling relations with a general deviation from self‐similarity, with a stronger albeit more controversial signal from the weaker 2020 stimulation. The 2020 earthquakes also tend to have a smaller local magnitude compared to 2018 earthquakes with the same moment magnitude. We discuss these connections in the context of fluid effects on rupture speed or medium properties. Site terms demonstrate that the spectral amplification relative to two reference borehole sites is not neutral at the other sensors; largest variations are observed at surface stations at frequencies larger than 30 Hz. Intrinsic attenuation is exceptionally low with values down to 2.4 × 10−5 at 20 Hz, which allows the observation of a diffuse reflection at the ∼50 km deep Moho. Scattering strength is in the range of globally observed data with between 10−3 and 10−4. The application of the employed Qopen analysis program to the 2020 data in a retrospective monitoring mode demonstrates its versatility as a seismicity processing tool. The diverse results have implications for scaling relations, hazard assessment and ground motion modeling, and imaging and monitoring using ballistic and scattered wavefields in the crystalline Fennoscandian Shield environment.

Quantifying the effect of amplitude scaling of real ground motions based on structural responses of vertically irregular and regular RC frames

Increasing number of real ground motion (GM) record databases raised nonlinear dynamic analysis (NDA) as an attractive option to determine structural response statistics. Structural responses are sensitive to input motions and the appropriate selection and scaling of real GMs is one of the crucial topics in earthquake engineering. In this paper, the influence of amplitude scaling on important earthquake demand parameters (EDPs), namely, global drift ratio, inter-story drift ratio and maximum floor acceleration, were studied using different scaling approaches and scaling limits. Eurocode-8 was used as a reference seismic code and amplitude scaling effects on structural responses of vertically irregular and regular structures were quantified. Efficiency and sufficiency of amplitude scaling were assessed in terms of mean, dispersion and non-exceedance probability curves of the EDPs. Statistical distribution of GM characteristics and their dependence on GM amplitude scaling were also discussed. Evaluations have shown that similar mean responses can be obtained regardless of scaling limits, approaches, and building topology if spectral shape compatibility is ensured. Furthermore, results demonstrated that neither building regularity nor scaling of GMs influenced the statistical distribution of ground motion parameters and non-exceedance probability curves of the EDPs. In fact, it was revealed that record selection scenario including spectral compatibility of individual GMs had a dramatic impact on dispersion and exceedance probability of structural responses.

Erratum: Amplitude scaling of ground motions as a potential source of bias: Large scale investigations on structural drifts

Earthquake Engineering & Structural DynamicsEarly View ERRATUMFree Access Erratum: Amplitude scaling of ground motions as a potential source of bias: Large scale investigations on structural drifts This article corrects the following: Amplitude scaling of ground motions as a potential source of bias: Large-scale investigations on structural drifts Konstantinos Theodoros Tsalouchidis, Christoph Adam, Volume 51Issue 12Earthquake Engineering & Structural Dynamics pages: 2904-2924 First Published online: June 26, 2022 First published: 11 March 2023 https://doi.org/10.1002/eqe.3868AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat In the original publication,1 Figure 2c contains the 50th percentile spectrum of the ground motion CHICHI.02-TCU105N instead of the 80th (as it should). The correct figure is shown here (together with the remaining sub-figures of Figure 2 for completion). It is noted that no other remarks or changes in the text are needed and none of the conclusions of the paper or the description of this figure in the text are affected. FIGURE 2Open in figure viewerPowerPoint (A) Acceleration response of an SDOF system with T = 1s; (B) response spectra for two GMs; (C) 80th percentile spectra for the same GMs. REFERENCE 1Tsalouchidis KT, Adam C. Amplitude scaling of ground motions as a potential source of bias: large-scale investigations on structural drifts. Earthquake Engng Struct Dyn. 2022; 51: 2904- 2924. doi: 10.1002/eqe.3707 Early ViewOnline Version of Record before inclusion in an issue FiguresReferencesRelatedInformation

SHAKER: A selector of consistent and energetically equalized natural ground motions using the Italian earthquake database

Input motion set selection for nonlinear dynamic structural analysis is commonly based on spectral compatibility, obtained through the uniform scaling of natural signals. Due to the aleatory nature of the expected time history, alone spectral compatibility requirement appears very weak to guarantee scaled ground motions that suit local seismic hazard. Magnitude-Distance interval pairs to control selection and scaling factor thresholds do not always provide input motions with adequate energy levels. In order to tackle these critical issues, a novel computer-aided selection method based on consistency analysis to provide conservative energy levels has been developed. The method equalizes the ground motions subject to the spectral compatibility process to the modified Housner Intensity of the hazard spectra. A multi-parametric consistency analysis based on statistic confidence is performed on the equalized (by uniform scaling) ground motion set by comparing it with the larger regional natural dataset on the same Magnitude-Distance pairs. The consistency analysis involves multiple ground motion parameters taken into relation with the focal mechanism too. Sensitivity tests show the capability of the method to reach high spectral compatibility joined with high consistency degrees by multi-parametric calibration. Compared with the traditional ones, this method also shows greater performance in composing ground motion sets close to real occurrences with a more assorted spectral frequency distribution.

Shake Table response of a dual system with inline friction damper

The purpose of this paper is to investigate the structural characteristics of a dual system moment frame and concentrically braced frame with a friction damper (CBFD). The experimental test involves the design, detailing, fabrication, and testing of a full-scale dual system frame on a uniaxial shake table subjected to 16 scaled ground motions of various intensities and amplitudes and eight artificially generated sinusoidal, sweep and step functions. The dual system utilized for this testing includes two ordinary moment-resisting frames and a single ordinary concentric braced frame with and without an inline friction damper. Overall, the friction damped braced system decreased the system acceleration by 25 percent at the frame deck. The friction-damped brace increased the damping of the dual system frame by 6.7 percent while maintaining story drift below 1.7 percent. The residual frame story drifts demonstrated that the ordinary moment-resisting frames participated as re-centering frames correcting any residual elongation in the friction damper. Overall, the inline friction damper assembled within the dual system frame demonstrated enhanced structural performance and resiliency.

Design and Construction of Elevated Multispan Bridge Structure for Light Rail Transit in Jakarta, Indonesia

The Greater Jakarta Light Rail Transit Project (LRT Jabodebek) is an infrastructure project that utilizes lead rubber bearings (LRBs) to reduce seismic demand on structures. This seismically isolated system shall provide operational performance levels under design earthquakes. Nonlinear time-history analysis was used to evaluate the structural performance. Five pairs of scaled ground motions were used as the input motions for the time-history analysis. The ability of the lead rubber bearing to isolate the structures and dissipate earthquake energy will determine its effectiveness in achieving the targeted structural performance level. From this exercise, the targeted performance was achieved. In the last part of the paper, the construction documentation of the elevated structures is presented.

Assessment of ground motion amplitude scaling using interpretable Gaussian process regression: Application to steel moment frames

AbstractThe process of ground motion selection and scaling is an integral part of hazard‐ and risk‐consistent seismic demand analysis of structures. Due to the lack of ground motion records that naturally possess high amplitude and intensity, the research community generally relies on scaling the records to match a target hazard intensity level. The scaling factors used are frequently as high as 10. Due to the criticism received in previous research studies, the extent of amplitude scaling and its process has become a matter of debate, and various constraints on the scaling factors have been proposed. The primary argument against unrestricted amplitude scaling is the unrealistic nature of the scaled records and the possible biases caused in the engineering demand parameters (EDPs) of structures. This study presents a framework to utilize machine‐learning and statistical techniques for the assessment of ground motion amplitude scaling for nonlinear time‐history analysis (NTHA) of structures. The framework utilizes Bayesian non‐parametric Gaussian process regressions (GPRs) as surrogate models to obtain statistical estimates of EDPs for scaled and unscaled ground motions. The GPR surrogate models are developed based on a large‐scale analysis of five steel moment frames (SMFs) using 200 unscaled as‐recorded ground motions for ten spectral acceleration levels, () (ranging from 0 g to maximum considered earthquake, MCE) and 2500 scaled ground motions representing 50 scale factors (), and the 10 levels for each SMF. For each building, two types of EDPs are considered: i) peak inter‐story drift ratio (PIDR) and ii) peak floor acceleration (PFA). To provide a better interpretation of the GPR surrogate models, the concept of explainable artificial intelligence (i.e., Shapley additive explanation, SHAP) is used to obtain insights into the decision‐making process of the GPR models with respect to the and . Then, for the 10 levels, the GPR‐based EDP estimates under scaled ground motions corresponding to 50 different SFs are compared with the EDP estimates of unscaled ground motions. The comparison is conducted using Kolmogorov–Smirnov (KS) statistical hypothesis test. Results indicate that the range of allowable s depends on two factors: i) intensity level (characterized by ), and ii) the dynamic properties of the building. In general, it is noticed that allowable s range between 0.5 and 3.0 for PIDRs, and from 0.6 to 2.0 for PFAs. Finally, the EDP between the unscaled and scaled ground motions are adhered to various discrepancies observed in different intensity measures representing amplitude‐, duration‐, energy‐, and frequency‐ content of the two sets of ground motions.