Ground Motion Characteristics Research Articles

Characteristics and Identification Method of Natural and Mine Earthquakes: A Case Study on the Hegang Mining Area

Accurate identification of natural and mine earthquakes in mining areas is of great significance to the construction of secondary disaster warning networks. Based on 490 records of natural and mine earthquakes in the Hegang area from 2006 to 2017, this paper compares and analyzes the ground motion characteristics of the research samples (150 earthquake records and 200 mine earthquake records) and selects the key identification parameters of dominant frequency, Pm/Tc, and Sm/Tc. The correct identification rate of the test samples (60 seismic records and 80 mine earthquake records) is 95.7%, 91.4%, and 93.6%, respectively, and the actual threat rate is 90.8%, 83.3%, and 86.3%, respectively. Finally, based on the selected key identification parameters, a “three-parameter comprehensive gradient discriminant method” is proposed. The correct identification rate and actual threat rate are 99.3% and 98.4%, respectively, which can basically accurately identify natural and mine earthquakes. It provides a certain method and theoretical support for the mining area vibration identification method, safety production, and disaster warning.

Selection of Ground Motion Intensity Measures in Fragility Analysis of a Mega-Scale Steel Frame Structure at Separate Limit States: A Case Study

Selecting an appropriate ground motion intensity measure (IM) to estimate the aleatory uncertainty produced by ground motion variability is the first and crucial step in fragility analysis. The choice of IM is influenced not only by the structural system type itself but also by the limit state of the structural damage. In this study, an investigation of the selection of IM in fragility analysis with respect to different limit states is developed for a 48-story mega-scale steel frame structure with buckling restrained braces. A comparative study of the efficiency of 27 IMs is conducted at four structural damage limit states, i.e., negligible, light, moderate, and severe, through the lognormal standard deviation estimated in fragility equations. In addition, for the purpose of considering the influence of different earthquake characteristics, two completely different sets of ground motions are selected, namely near-field pulse-like and far-field earthquakes. The research shows that the ground motion characteristics and structural damage limit states have nonnegligible effects on the flexibility of intensity measures. For combination-type IMs, the number of combined terms and the combined power index have a significant impact on their performance; thus, an optimized dual-parameter combination-type intensity measure is recommended.

Numerical Investigation of the Effects of Ground Motion Characteristics on the Seismic Behavior of Liquefiable Soil

The seismic behavior of liquefiable soils can be significantly influenced by many ground motion characteristics. Therefore, it is crucial to identify the ground motion characteristics that have the most significant effects on the seismic behavior of liquefiable soils. In this paper, a series of nonlinear numerical analyses were performed to investigate the influence of ground motion characteristics on the seismic behavior of loose liquefiable soil. The liquefiable soil profiles were built with the same relative densities but different layer thicknesses. In order to clarify the effect of the ground motion characteristics on the liquefiable soil mechanism, soil profiles were subjected to ground motion sets having different characteristics, such as maximum horizontal accelerations, frequency contents, and significant durations. The numerical analyses were performed using the open-source program OpenSees. The results were presented and discussed in terms of peak ground acceleration, amplification ratio, maximum excess pore pressure ratio, maximum shear strain, and maximum lateral displacement. The results indicated that the maximum horizontal acceleration and the frequency content greatly influence the site response behavior of the liquefiable soil. Furthermore, the nonlinear behavior of the soil is more obvious on being subjected to long-duration ground motions as compared to shorter duration ground motions having the same maximum horizontal acceleration. The findings presented in this study could be helpful when analyzing the seismic response of liquefiable soils coupling superstructures.

Spatial and Temporal Distribution of Lobate Scarps in the Lunar South Polar Region: Evidence for Latitudinal Variation of Scarp Geometry, Kinematics and Formation Ages, Neo‐Tectonic Activity and Sources of Potential Seismic Risks at the Artemis Candidate Landing Regions

AbstractLobate scarps (thrust faults) in the lunar south polar region (90°–60°S) provide important insights into tectonic history, seismicity, and seismic hazard potential of landing sites. In this study, we discovered 75 new lobate scarps and >500 segments, exhibiting latitudinal variation of geometry and movement directions. Formation ages of 141 prominent scarp segments show fault growth rates and directions, decreasing ages from south pole to mid‐latitude, continuous tectonic activity in the last 100 million years with a peak around 10 Ma, seismic resetting of ages, and timings of global contraction. The scarps are capable of producing small‐medium size moonquakes within 5–10 km depths. The deterministic seismic hazard analysis, considering occurrence of MW 1–4 shallow moonquakes along the scarps in the next few decades, and their seismic ground motion characteristics, suggests variable levels of potential seismic risk at the Artemis candidate landing regions and further probabilistic seismic hazard analysis is necessary.

Pseudo-Dynamic Test on Composite Frame with Steel-Reinforced Recycled Concrete Columns and Steel Beams

Pseudo-dynamic tests were conducted on a 2/5-scaled, three-story, two-span frame with steel-reinforced recycled concrete (SRRC) columns and steel beams. The El-Centro earthquake waves, Taft earthquake waves, and Lanzhou artificial earthquake waves were considered as the main loads to study the seismic behavior. The failure modes, displacement and acceleration time history curves, hysteretic characteristics, energy dissipation, stiffness degradation, and inter-story drift capacity of the composite frame were analyzed. Results showed that the composite frame did not show plastic deformation during the whole test process, and the steel beams and columns basically did not yield. Under the action of three seismic waves, the displacement response, acceleration response, and restoring force response of the composite frame were increased with seismic intensity, while the hysteretic curves and energy dissipation were different as the seismic wave changed. The seismic response of the composite frame was greatly affected by the spectral characteristics of the loading ground motion and the hysteretic energy mainly consisted of recoverable elastic deformation energy. Under the action of Taft wave with the input peak acceleration of 400 gal (rare earthquake), the stiffness degradation of composite frame was the largest, which reduced to 47% of the initial stiffness. This indicated that the composite frame had good energy dissipation performance in the elastic and elastic-plastic stages, and still possessed good rigidity after a rare earthquake, fully achieving the design purpose of “no collapse in major earthquake”.

Selection of seismic isolation system parameters for the near-optimal design of structures

The benefits of seismic isolation are many. Structures that are isolated from the ground seismically perform better than those that are not. They experience reduced floor accelerations and drifts and are less likely to experience damage to structural elements. Additionally, their contents are better protected from the effects of earthquakes. The selection and design of seismic isolation devices are complex and require a good understanding of how they behave during earthquakes. This study investigates the effect of various isolation system parameters and ground motion characteristics on the seismic response of base isolated structures in order to develop rational procedures for design and analysis. Additionally, the study investigates the problem of optimal design of seismic isolation systems through parametric nonlinear dynamic analysis. Results showed that the maximum base shear and displacement were velocity-sensitive and that the peak ground velocity controls the motion. The largest maximum base shear occurred when using isolation systems with high yield strength levels and low degrees of nonlinearity, while the smallest maximum base shear occurred when using low yield strength levels and high degrees of nonlinearity. Results from the study can be used to select the appropriate isolation devices and design them correctly to achieve the benefits they provide.

An advanced intensity measure for aftershock collapse fragility assessment of structures

A ground motion intensity measure (IM) characterizes the damage potential of seismic ground motion on a structure and makes a connection between the structural response analysis and seismic hazard analysis. During earthquake events, aftershocks (ASs) are usually observed following a mainshock (MS), having no time for repairing between the events. For developing a framework to integrate aftershock seismic hazard into performance-based earthquake engineering, it is essential to apply an IM that accounts for the damage state experienced by the structure under the MS event. In the present study, the ability of some well-known and advanced IMs to predict the collapse capacity of reinforced concrete moment resisting frames (RC MRFs) under mainshock-aftershock (MS-AS) sequences with low dispersion is investigated. This ability for an IM is denoted as its efficiency. Furthermore, the potential bias in the collapse capacity values predicted using the IMs, with regard to ground motion characteristics is tested. The ability of an IM for reducing the bias to predict the seismic response or damage state capacity is denoted as sufficiency. The results show that the efficiency of the IMs for collapse capacity prediction of the structures under MS-AS sequences decreases when compared with the results obtained from only MS records as a prevalent method. In addition, most of the IMs that have high efficiency, do not have high sufficiency with regard to scale factor or magnitude (or both). The multi-objective particle swarm optimization algorithm is applied to develop an optimal IM with high efficiency and sufficiency for collapse capacity prediction of RC MRFs.

Strong ground motion data of the 2015 Gorkha Nepal earthquake sequence in the Kathmandu Valley

Strong-motion records of earthquakes are used not only to evaluate the source rupture process, seismic wave propagation and strong ground motion characteristics, but also to provide valuable data for earthquake disaster mitigation. The Kathmandu Valley, Nepal, which is characterised by having soft sediments that have been deposited in an earthquake-prone zone, has experienced numerous earthquakes. We have operated four strong-motion stations in the Kathmandu Valley since 2011. These stations recorded the 2015 magnitude 7.8 Gorkha Nepal earthquake that occurred in the Himalayan continental collision zone. For several months after the mainshock, we deployed four additional temporary stations. Here, we describe the seismic data for 18 earthquakes over magnitude 5.0 collected by this array, including the 2015 magnitude 7.3 Dolakha earthquake of maximum aftershock and three large aftershocks of magnitude 6-class. These data are essential for validating the sedimentary structure of the basin and for evaluating the hazard and risk of future earthquakes in the Kathmandu Valley.

Ground Motion and Site Characteristics Evaluation Using Hilbert-Huang Transform Method Based on Light-Moderate Earthquakes

Compared with strong earthquakes (Ms ≥ 6.0), light-moderate earthquakes (Ms 4–5.9) occurred more frequently and distributed more widely, and rich ground motions have been collected around world. It provides a solid data base for the investigation on the ground motion and regional site characteristics which are closely related to seismic geological disaster. We chose two light-moderate earthquakes in China as study cases. Based on Hilbert-Huang transform, we analyzed the ground motion characteristics in time-frequency domain. Using a stable coda wave and marginal spectrum of it based on horizontal to vertical Fourier spectral ratio (HVSR) method, the site characteristics are clarified. Result shows that the amplitude (instantaneous frequency energy) of Hilbert-Huang spectrum is mainly concentrated within 20 Hz at the stations that are close to epicenter. The energy will change from concentration to divergence in time and frequency and decrease with the increase of epicenter distance under soil site condition. Two earthquakes present a low prominent frequency characteristic (1.075–2.45 Hz). Hilbert energy at soil layer is about 3 times greater than it at rock site when the epicenter distance is close and soil layer can also amplify the instantaneous energy. The predominant frequency of site at each station is within 3.6–6.2 Hz. The predominant frequencies of the earthquakes are lower than the predominant frequencies of the sites and would not produce resonance effects. The result can provide meaningful references for later study works about the characteristics and application of light-moderate earthquakes.

Spatial variation of structural fragility due to supershear earthquakes

Collapse fragility of structures is studied using equipotent subshear and supershear earthquakes. Supershear earthquakes propagate at a speed faster than the shear-wave speed of the medium, thereby producing significantly different ground motion characteristics than subshear ruptures. In particular, fault parallel component dominance is established in the literature for supershear events. By considering a set of stations parallel to the strike of the fault, and another set perpendicular to the strike of the fault at various distances, fragility curves are derived as a function of distance from the fault in the near-field. In addition, the fault-parallel and fault-normal components in the near-field are applied separately to single-degree-of-freedom systems with peak-oriented modified Ibarra–Medina–Krawinkler hysteretic behaviour to characterize the component-wise differences across the subshear and supershear cases. A comparison of the median fragilities with HAZUS suggested values of similar structural systems is also presented.

Seismic reliability evaluation of spatially correlated pipeline networks by quasi-Monte Carlo simulation

The reliability assessment of pipeline networks under nature disasters helps to improve the disaster prevention capability and overall resilience of pipeline networks. For the earthquake hazard, the seismic damage of pipelines in the network is usually correlated due to the spatial correlation of critical parameters, including characteristics of pipeline, soil properties and ground motions. This paper proposes a framework to evaluate the seismic reliability of pipeline network under spatially correlated parameters based on the quasi-Monte Carlo (QMC) simulation. The influence of spatial correlated random variables on the seismic reliability of pipeline network is investigated with explicit consideration of the correlated random variables including the peak ground velocity, the wall thickness and the yield stress of pipe segment. The framework has been implemented in seismic reliability evaluation of two pipeline networks. The result shows that the QMC method has better simulation accuracy than the standard MC method under same sampling numbers. The spatial correlations have different influences on the seismic connectivity reliability of pipeline networks with different topological redundancy and parallelism of connective paths from sources to user nodes. For the pipeline network with greater redundancy and parallelism, the model without considering the spatial correlations overestimates the network connectivity reliability.

Analysis of Multistorey RCC Frame subjected to Mainshock and Aftershock Earthquake

Abstract: Structure analysis and design are significantly influenced by earthquake. It is believed that seismic evaluation is required for the viability and serviceability of both present and future building structures. When a structure's base is subjected to a certain type of ground motion, a time history analysis is performed to examine the dynamic reaction of the structure at each time interval. The near-field earthquake ground motion verification may have specific impacts for both forward and backward directivity. The initial's velocity and displacement motions, respectively, exhibit pulse and fling-step characteristics. Therefore, it is crucial to assess how well structures built solely to withstand the primary shock would work through future aftershocks. Using modern seismic protection systems, such as base isolations or / and supplemental dampening devices, that significantly reduce building damages during main shocks and their related aftershocks is one of the appropriate solutions to this issue. Due to changes in both static and dynamic stress that take place during the earthquake process, aftershock events are set off by the primary shock. In order to better understand the ground motion features of a sizable collection of mainshock and subsequent aftershock ground motion data recorded in accelerograph stations around the region, this study reviews pertinent literature in the field. The G+9 RCC building will be used in this study to conduct a time history analysis of the mainshock and aftershock data of the Chamoli earthquake provided by the Centre for Engineering Strong Motion Research Ground Motion Database. For designing purposes, the IS 456-2000 code is taken into consideration. Live loads are measured in accordance with IS 875-part 1, and seismic zone IV is selected for analysis in accordance with IS 1893-2016. Storey drift, base shear, joint reactions, and storey displacement are just a few of the variables that can have an impact on how well a building performs. Since each of these variables has a significant impact on how a structure responds to seismic loads, they are also taken into account when evaluating the results.

Seismic fragility assessment for cantilever retaining walls with various backfill slopes in South Korea

We evaluate seismic fragilities for cantilever retaining walls with three slope angles of backfill (i.e., 0, 10°, and 20°), subjected to the ground motions computed for four site classes (S2, S3, S4, and S5). We collect measured shear wave velocity profiles and select representative profiles. Using one-dimensional site response analyses, surface ground motions are computed corresponding to various site conditions. Numerical models are developed for a cantilever retaining wall with a height of 4 m using the FLAC2D software, and are verified by a comparison with an analytical solution. We analyze the correlations between the seismic behavior of the retaining wall and various ground motion parameters. A probabilistic seismic demand model is introduced to calculate the probabilities of exceeding three limit states of retaining walls, based on the relative wall displacements and settlements of the backfills. We propose a suite of seismic fragility curves which are functions of either the peak ground acceleration (PGA) or cumulative absolute velocity (CAV). In addition, we propose a suite of seismic fragility surfaces using dual ground motion parameters (PGA and CAV). The results highlight that the backfill slope angle and ground motion characteristics have a primary influence on the probabilities. When the backfill slope angle increases from 0 to 20°, the probabilities of exceeding the three limit states increase by up to approximately 1.7, 4.0, and 8.5 times, respectively. Additionally, the probabilities for S3 ground motions with a PGA of 0.4 g are higher than those for S2 motions with the same PGA by up to approximately 5, 16, and 36 times, respectively.

Rapid seismic response prediction of RC frames based on deep learning and limited building information

Building portfolio is the important urban engineering system, and the seismic resilience assessment of a city needs the quick and accurate prediction of the seismic responses of existed buildings. However, many existed buildings generally possess the problem that the design information materials are incomplete or completely lost. The major challenge in the seismic resilience assessment of building portfolio is how to predict the seismic responses of buildings quickly and accurately just using limited building information. This manuscript aims to develop a method for the seismic response prediction of the existed reinforced concrete (RC) frame buildings just using limited building information. A total of 162 typical RC frame buildings of low to medium rise are designed, and the inter-story drift (IDR) as well as peak floor acceleration (PFA) of each floor in each building are computed for 200 ground motions with nonlinear time history analysis (NLTHA) method. A convolutional neural network (CNN) is developed with ground motion records and five easy-getting building parameters as inputs. The outputs are IDR and PFA of each floor for the given building. Considering the physical means of an input parameter—number of stories, the modified loss function and modified evaluation function are proposed. The developed network is trained with the computed dataset and the modified loss function, and the trained model (referred to StruNet) can take the characteristics of ground motions and structures into consideration together comparing to previous studies. The proposed model is verified through four cases (i.e., 4 actual buildings with different construction time, occupancy types, and plane layouts), which are independent of the deep learning dataset. The results confirm that the proposed method offers prediction results with sufficient accuracy and shows high computational efficiency.

Seismic control of the structures with active tuned mass damper and variable fractional order fuzzy proportional–integral–derivative controller

The structural control of the building is a critical part of mitigating the catastrophic consequences of the earthquakes. The active control of structures has gained popularity in the construction industry because of its ability to adapt to different ground motion characteristics. The active tuned mass damper (ATMD) is one of the most versatile devices used for active structural control. This paper uses the ATMD and variable fractional order fuzzy PID (VFOFPID) controller for improving the performance of building structures subjected to horizontal ground motions. Having obtained the response of an 11-story shear building with this controller, the optimized control forces are determined through the pattern search algorithm and the performance indices of the system subjected to 100 different ground motions are evaluated. The performance indices are compared with those of uncontrolled as well as genetic fuzzy and fuzzy PID controlled structure. The results indicate that the VFOFPID controller proposed here can effectively reduce the drift and the absolute acceleration of the structure.

Dynamic Behaviour Of Geodesic Dome Structure For Different Time Histories

<p>Earthquake is caused by a sudden release of energy in the earth’s crust, which causes seismic waves. The most significant effects of earthquakes are ground shaking and rupture. It has both social and economic effects, such as causing death and injury to creatures, including humans, and may damage the natural and build environment. It is critical to comprehend the loss of life and damage to structures caused by ground motion. So, the ground motion characteristics are to be studied keenly on any structure in the design process. In the present study different time histories are used to perform dynamic analysis of a geodesic dome using the analytical approach. The results like base shear and joint displacements are obtained with respect to the ground motion time period.</p>

Development and Application of a Platform for Multidimensional Urban Earthquake Impact Simulation

Earthquakes can be devastating to cities. Therefore, accurate and efficient simulation of the potential seismic damage to buildings has become an indispensable part of worldwide efforts to mitigate earthquake hazards. Precise simulation results can highlight potential seismic damage and serve as a reference in urban development and for planning post-earthquake rescue operations. In urban areas, simulation of the structural dynamic response during an earthquake is key for planning an appropriate emergency response. Multidimensional visualization of the effects of earthquakes is a popular technique in current earthquake simulation research. In the present study, a dynamic multidimensional simulation method was developed for analyzing the impact of an earthquake on buildings. This method involved conducting three-dimensional (3D) dynamic analysis of data from a seismic capacity database. Polygonal models and seismic capacity data were used in a high-performance computing process to calculate the seismic response of each building in an urban environment. On the basis of the calculations, a platform was developed for multidimensional urban earthquake impact simulation (MDUES). The developed MDUES platform enables analysis of the impact of long-period earthquakes, simulation of the 3D seismic responses of buildings, and visualization of the disaster risk and earthquake impact in a specified area. In summary, simulation of structural seismic responses in an urban setting necessitates a careful examination of the characteristics of ground and building motion, and the results of this simulation can provide a crucial reference for city planning, post-earthquake rescue operations, and seismic damage assessments.

Effects of spatial variability of soil properties and ground motion characteristics on permanent displacements of slopes

The seismic performance of earth slopes is a problem of great importance in geotechnical earthquake engineering associated with various sources of uncertainty. This research investigates the effects of two important causes of such uncertainty: (a) the spatial variability of soil properties and (b) the variability of the temporal and frequency characteristics of the earthquake excitation. The former is investigated based on a series of detailed dynamic numerical simulations using stationary random fields of both cross-correlated and spatially autocorrelated soil properties. The latter is explored by conducting incremental dynamic analysis at various levels of excitation intensity using (a) a total of forty historic earthquake and synthetic records, modified to match the Eurocode 8 design spectra for rock sites, and (b) thirty original historic earthquake records. The results demonstrate the significant effect of the spatial variability of soil properties on the permanent slope displacements. Moreover, they show that the effect of the uncertainty associated with the variability in the temporal and frequency characteristics of excitations is more important compared to the effect of the spatial variability of soil properties.

Attenuation Characteristics of High-Frequency Ground Motions from Local Sources Caused by Great Subduction Zone Earthquakes in Northeast Japan

AbstractGround-motion attenuation characteristics are examined for the peak ground accelerations (PGAs) and peak ground velocities (PGVs) from strong-motion generation areas (SMGAs), which emit strong high-frequency waves during great subduction zone earthquakes. A conventional ground-motion prediction equation (GMPE) for earthquakes is designed based on the magnitude and distance from the source fault to predict the peak ground motion amplitude. For great subduction zone earthquakes, significant wavetrains of high-frequency ground motions are often separately observed in seismograms, and the corresponding rupture areas are estimated as SMGAs along the plate interface. In this case, although the advantages of using the shortest distances measured from the closest SMGAs rather than the shortest fault distance have been confirmed in previous studies, it is more physically reasonable to examine the ground-motion attenuation characteristics of individual SMGAs based on their magnitudes and locations. Therefore, we examine the attenuation characteristics of the PGAs and PGVs of individual SMGAs of the 2003 Mw 8.2 Tokachi–Oki earthquake and 2011 Mw 9.1 Tohoku earthquake in the Japan subduction zone considering data at stations within an SMGA distance of 300 km and the SMGA moment magnitude. The model, exhibiting the same functional form as a conventional GMPE, is fitted to the PGA and PGV data pertaining to each SMGA that are normalized to a bedrock site with VS30=760 m/s at any distance. The uncertainties in the obtained PGAs and PGVs are 3.6% and 13.5% lower, respectively, in terms of the residual in logarithmic units than those in the results of previous approaches considering only the SMGA distance. This result could help develop GMPEs for SMGAs to more appropriately predict the strong motions generated during great subduction zone earthquakes.

Empirical Correlations between the Spectral Input Energy and Spectral Acceleration

ABSTRACT Correlating different intensity measures (IMs) enables the joint consideration of multiple IMs in various performance-based earthquake engineering applications, such as ground motion selection. The correlations between the spectral input energy and spectral accelerations have not been previously examined. This study develops a correlation model quantifying the uncertainties due to GMPE selection and a finite sample size. The results show a strong correlation between the spectral amplitudes at the same period, and the correlation decreases as the period difference increases. With the proposed model, ground motion characteristics reflected by the input energy can be explicitly considered in performance-based earthquake engineering applications.