Different Types Of Earthquakes Research Articles

Effect of damper mass on soil-structure displacement in dynamic response to earthquake vibration with finite element modelling

Earthquake is a natural disaster that always occur inside the region of pacific ring of fire. Many structures such as high-rise buildings, bridges, dams and many more failed and take severe damage due to the impact of the strong vibration of the earthquake. A pile foundation is a type of deep footing which is suitable for high-rise buildings founded on clay soils where its function to prevent potential failures such as bearing capacity and collapse. In addition, the problem of tall buildings is prone to sway and damaged when earthquake strike and such vibrations cause the dynamic behaviour of structure to change significantly in terms of excessive lateral displacements and accelerations. Thus, the effect of damper mass on soil-structure displacement in dynamic response to earthquake vibration was determined. The effectiveness of vibration absorber to the single pile structured in clay soil was modelled and simulated in finite element program PLAXIS 3D version 20 with and without the presence of the damper where the inputs were taken from the Sumatera and Chi – chi earthquakes. The problem was modelled and simulated by drawing a geometry, assigning the soil and pile materials input, loading and boundary conditions, meshing generated and staged construction for calculations of displacement structure output in response to dynamic due to earthquake vibration. The displacement-time with the effect of mass of the vibration with and without absorber are presented. The results show a good performance of damper on the single pile structured on soft soil with different types of earthquakes.

Efficiency of Friction Pendulum Bearings in Vertically Irregular Structures Subjected to Various Types of Earthquakes

The attention towards seismic mitigation using passive control systems has increased significantly over the last few decades to reduce earthquake demands and achieve the required performance objectives. Nowadays, friction pendulum bearings have proven efficient in mitigating regular RC structures subjected to a wide range of earthquakes. Nonetheless, limited studies were dedicated to investigating the performance and efficiency of this type of isolation system utilized in RC structures with various types of vertical irregularities. Besides, comprehensive parametric assessments that investigate the behavior of structures supported on friction pendulum bearings subjected to pulse-like and non-pulse-like earthquakes are scarce. Thus, this study aims to assess the behavior of RC frames equipped with friction pendulum isolators under different types of earthquakes. In the context of the paper, three types of vertical irregularities, known as soft-story, heavy-story, and stepped structures, will be modeled and investigated. Moreover, the outcomes of these buildings will be benchmarked to a regular model to illustrate the efficiency of the selected isolation systems. Furthermore, the performance of the base-isolated buildings with friction pendulum isolators subjected to pulse-like and non-pulse-like earthquakes will be reported. In general, the study results have shown that pulse-like earthquakes exhibited higher values than non-pulse-like earthquakes for the different responses of the structures at the periods of 2.5 and 3 and the damping ratios of 15%, 20%, and 25%. Doi: 10.28991/CEJ-2022-08-09-05 Full Text: PDF

Evaluation of the Methods Used to Calculate the Structural Damage Index for Reinforced Concrete Structures Exposed to Various Earthquakes

This study deals with the structural evaluation and compression is made between the methods of calculating the damage index of a two-dimensional reinforced concrete structure. A three bay, ten storys frame was designed based on the specifications of the American Concrete Institute (ACI 318-19), the structure was analyzed by non-linear dynamic analysis method by exposing the frame to three different types of earthquakes using (ETABS Version 19.0.0) program. Several methods proposed by researchers were used for calculating the total damage indices of the structure, another method was suggested in the present work, there was convergence in the values calculated on the basis of the composite methods of physical and engineering variables compared with the methods that depend on engineering variables only, such as ductility or displacement. The damage indices based on physical variables only, such as the hysterical dissipated energy, was considered ineffective in representing the real damage, especially in the case of medium and large damages, and it is advisable to adopt more than one method to ensure the safety of the structure and not to rely on one method determined by a few variables in order to express the exact and actual damage in all aspects.

Dynamic modelling and control of shear-mode rotational MR damper for mitigating hazard vibration of building structures

Magneto-rheological (MR) materials and their devices are being rapidly developed and have drawn surge of interest for the potential application in vibration control. Among them, a novel shear-mode rotational MR damper (SM-RMRD) with adaptive variable stiffness and damping was developed for adaptive structural control in real-time against different types of earthquakes. To make use of this innovative device perfectly, a robust and reliable model should be developed to simulate the nonlinear and hysteretic behaviours for the application in adaptive control. Accordingly, this research initially presents a new phenomenological model to describe the force response of the SM-RMRD. Then, model parameters are estimated based on experimental data of force, displacement and velocity, which were directly or indirectly obtained from the device under different loading protocols. The field dependence of each model parameter is also investigated so that a general model with current-related parameters is acquired for designing the control strategy. Using the current-dependent model of SM-RMRD, a semi-active controller is developed and implemented to the SM-RMRD to produce the feedback control for the structures in real-time. Finally, the effectiveness of proposed control method is appraised by a numerical study, in which an SM-RMRDs-incorporated three-storey building model with different control strategies are subjected to various scaled benchmark earthquakes. The comparison result verifies the excellent capacity of the proposed controller based on the developed phenomenological model in terms of reducing the storey acceleration and inter-storey drift.

A numerical investigation of seismic performance for an RC frame with latticed concrete infill walls

Expansive polystyrene granule cement (EPSC) latticed concrete wall can be used as an infill wall. After the expanded polystyrene granule cement form has been demolished, the part that remains is a latticed concrete infill wall comprising lattice beams and columns whose cross section is circular with a diameter of 0.12 m. The horizontal and vertical rebar are arranged within the beams and columns. The dynamic responses of a full-scale single-story reinforced concrete (RC) frame with latticed concrete infill walls subjected to earthquake-induced ground motion are simulated using the nonlinear finite element ABAQUS software. This study aims to investigate the effects of different types of earthquakes on the structure and the acceleration responses of the structure. The results obtained indicate that the structure has excellent seismic behavior, although the structural responses vary between earthquakes. This research may help in promoting the design and application of RC frames with latticed concrete infill walls.

Evaluation of responses of semi-rigid frames at target displacements predicted by the nonlinear static analysis

Responses of semi-rigid frames having different degrees of semi-rigidity obtained by the nonlinear static analysis (NSA) are evaluated at specific target displacements by comparing them with those obtained by the nonlinear time-history analysis (NTHA) for scaled earthquakes. The peak ground accelerations (PGA) of the earthquakes are scaled such that the obtained peak top story displacements match with the target displacements. Three different types of earthquakes are considered, namely, far-field and near-field earthquakes with directivity and fling-step effects. In order to make the study a comprehensive one, three degrees of semi-rigidity (one fully rigid and the other two semi-rigid), and two frames having different heights are considered. An ensemble of five-time histories of ground motion is included in each type of earthquake. A large number of responses are considered in the study. They include the peak top-story displacement, maximum inter-story drift ratio, peak base shear, total number of plastic hinges, and square root of sum of the squares (SRSS) of the maximum plastic hinge rotations. Results of the study indicate that the nonlinear static analysis provides a fairly good estimate of the peak values of top-story displacements, inter-story drift ratio (for shorter frame), peak base shear and number of plastic hinges; however, the SRSS of maximum plastic hinge rotations in semi-rigid frames are considerably more in the nonlinear static analysis as compared to the nonlinear time history analysis.

Overview of the development of smart base isolation system featuring magnetorheological elastomer

Despite its success and wide application, base isolation system has been challenged for its passive nature, i.e., incapable of working with versatile external loadings. This is particularly exaggerated during near-source earthquakes and earthquakes with dominate low-frequency components. To address this issue, many efforts have been explored, including active base isolation system and hybrid base isolation system (with added controllable damping). Active base isolation system requires extra energy input which is not economical and the power supply may not be available during earthquakes. Although with tunable energy dissipation ability, hybrid base isolation systems are not able to alter its fundamental natural frequency to cope with varying external loadings. This paper reports an overview of new adventure with aim to develop adaptive base isolation system with controllable stiffness (thus adaptive natural frequency). With assistance of the feedback control system and the use of smart material technology, the proposed smart base isolation system is able to realize real-time decoupling of external loading and hence provides effective seismic protection against different types of earthquakes.

Load-induced seismicity near Tsaoling, Taiwan

Recent work shows erosion reduces vertical normal stress, triggering thrust earthquakes. Whether deposition will inhibit earthquake triggering, or favor different types of earthquakes is not clear. Here we address this question using earthquake catalogs, earthquake focal mechanisms, and a point-load stress transfer model to study induced seismicity at the Tsaoling impoundment after the 1999 Mw7.6 Chi-Chi earthquake. This impoundment formed when a river was blocked by the mainshock-induced landslide. Temporally, we found a marked increase and decrease in earthquake activities in this location at the beginning and end of this impoundment life cycle. Spatially, the number of earthquakes decreased away from the impoundment in a pattern correlated with surface point load models based on both the Boussinesq and Westergaard equations. Using first motions and SH to P amplitude ratios, we derived focal mechanisms, and found the point source on surface weakens the strike-slip and normal fault planes mostly occurred during our study period. Some of the Chi-Chi aftershocks not explained by dislocation stress transfer studies can be explained by such load-induced seismicity. Previous studies show earthquakes can affect surficial geological processes; this study suggests that surficial processes can create positive loading that feedbacks and triggers seismicity.

Gravity and Displacement Variations in the Areas of Strong Earthquakes in the East of Russia

The modern gravimetry methods are capable of measuring gravity with an accuracy of up to 10–10 of the normal value, which is commensurate with the accuracy of the up-to-date methods of displacement measurements by satellite geodesy. Significant changes, e.g., in the coseismic displacements of the Earth’s surface are recorded in the zones of large earthquakes. These changes should manifest themselves in the variations of gravity. Absolute measurements have been conducted by various modifications of absolute ballistic gravimeters GABL since the mid-1970s at the Klyuchi point (Novosibirsk) in the south of the West Siberian plate. Monitoring observations have been taking place in the seismically active regions since the 1990s. In this paper we consider the results of the long-term measurements of the variations in gravity and recent crustal displacements for different types of earthquakes (the zones of shear, extension, and compression). In the seismically active areas in the east of Russia, the longest annual series of absolute measurements starting from 1992 was recorded in the southeastern segment of Baikal region. In this area, the Kultuk earthquake with magnitude 6.5 occurred on August 27, 2008, at a distance of 25 km from the observation point of the Talaya seismic station. The measurements in Gornyi (Mountainous) Altai have been conducted since 2000. A strikeslip earthquake with magnitude 7.5 took place in the southern segment of the region on September 27, 2003. The effects of the catastrophic M = 9.0 Tohoku, Japan, earthquake of March 11, 2011 were identified in Primor’e in the far zone of the event. The empirical data are consistent with the results of modeling based on the seismological data. The coseismic variations in gravity are caused by the combined effect of the changes in the elevation of the observation point and crustal deformation.

Fatigue failure of 350WT steel under large-strain seismic loading at room and subfreezing temperatures

Due to its high ductility, weldability and toughness at low temperature, CSA G40.21-350WT steel in Canada is primarily used in bridge construction, ship building, and seismic energy dissipation systems. This article presents uniaxial tensile tests and constant- and variable-amplitude cyclic testing performed on 350WT steel at room and subfreezing temperatures. The variable-amplitude tests include common step-loading patterns as well as tests under strain signals obtained from the brace response in building structures subjected to three different types of earthquakes. The ductility of 350WT steel from monotonic tensile tests is essentially same at room and low temperatures (−40°C). The cyclic test results revealed that cold temperatures as low as −35°C did not have adverse effects on the low cycle fatigue life of 350WT steel. The benchmark constant-amplitude tests were employed to predict fatigue life under different large-strain variable-amplitude loading patterns both for room and subfreezing temperature conditions. In addition to the common strain-life approach, the adequacy of two well-established energy-life models for predicting fatigue life under variable-amplitude loading was evaluated. The strain-life approach generally performed better than the energy-life methods, particularly for step-loading histories. Comparison between predictions and laboratory observations showed that the fatigue failure life under large strain seismic loading can be accurately estimated, especially at room temperature.

Effect of slip-area scaling on the earthquake frequency-magnitude relationship

The earthquake frequency-magnitude relationship is considered in the maximum entropy principle (MEP) perspective. The MEP suggests sampling with constraints as a simple stochastic model of seismicity. The model is based on the von Neumann’s acceptance-rejection method, with b-value as the parameter that breaks symmetry between small and large earthquakes. The Gutenberg–Richter law’s b-value forms a link between earthquake statistics and physics. Dependence between b-value and the rupture area vs. slip scaling exponent is derived. The relationship enables us to explain observed ranges of b-values for different types of earthquakes. Specifically, different b-value ranges for tectonic and induced, hydraulic fracturing seismicity is explained in terms of their different triggering mechanisms: by the applied stress increase and fault strength reduction, respectively.

Self-Tuning Fuzzy Control for Seismic Protection of Smart Base-Isolated Buildings Subjected to Pulse-Type Near-Fault Earthquakes

Pulse-type near-fault earthquakes have obvious long-duration pulses, so they can cause large deformation in a base-isolated system in contrast to non-pulse-type near-fault and far-field earthquakes. This paper proposes a novel self-tuning fuzzy logic control strategy for seismic protection of a base-isolated system, which can operate the control force of the piezoelectric friction damper against different types of earthquakes. This control strategy employs a hierarchic control algorithm, in which a higher-level supervisory fuzzy controller is implemented to adjust the input normalization factors and output scaling factor, while a sub-level fuzzy controller effectively determines the command voltage of the piezoelectric friction damper according to current level of earthquakes. The efficiency of the proposed control strategy is also compared with uncontrolled and maximum passive cases. Numerical results reveal that the novel fuzzy logic control strategy can effectively reduce the isolation system deformations without the loss of potential advantages of base-isolated system.

Båth's law and its relation to the tectonic environment: A case study for earthquakes in Mexico

We studied 66 mainshocks and their largest aftershocks in the Mexican subduction zone and in the Gulf of California with magnitudes in the range of 5.2<Mw<8.0 from 1932 to 2015. Three different types of earthquakes were analyzed: shallow thrust interplate, intermediate-depth inslab and transform strike-slip earthquakes (26, 19 and 21 events, respectively). We focus on observational aspects of the Båth's law. By studying the magnitude difference, energy ratios and energy partitioning of the mainshock-largest aftershock sequences, we analyze the physics of the mainshock-largest aftershock relationship (Båth's law). The partitioning of energy during a mainshock-aftershock sequence shows that about 96–97% of the energy dissipated in a sequence is associated with the mainshock and the rest is due to aftershocks. Our results for radiated seismic energy and energy-to-moment ratio are partially in agreement with worldwide studies supporting the observation of mechanism dependence of radiated seismic energy. The statistical tests indicate that the only significant difference is for shallow thrust and strike-slip events for these parameters. The statistical comparison of stress drop of shallow thrust versus that of inslab events shows a strongly significant difference with a confidence better than 99%. The comparison of stress drop of shallow thrust events with that of strike-slip events, also indicates a strongly significant difference. We see no dependence of stress drop with magnitude, which is strong evidence of earthquake self-similarity. We do not observe a systematic depth dependence of stress drop. The results also reveal differences in the earthquake rupture among the events. The magnitude difference between the mainshock and the largest aftershock for inslab events is larger than interplate and strike-slip events suggesting focal mechanism dependence of Båth's law. For the case of this parameter, only that for inslab and strike-slip events present a significant difference with 95% confidence.

Differences in Epicentral Location of Mexican Earthquakes between Local and Global Catalogs: An update

Differences in epicentral locations between local and global catalogs for earthquakes in the Mexican subduction zone were first observed to be biased in the 1980s, based on a few well studied events. In this study we compare locations between two local catalogs; (1) a recent high precision catalog of events in the state of Guerrero and (2) the catalog of the Servicio Sismológico Nacional (SSN), to the global catalog of the United States Geological Service (USGS). We find that on average epicentral locations in the global catalog of earthquakes larger than M 5 in the Mexican subduction zone are 26 km towards N54°E of those in the local catalogs. We investigate how the errors vary for different types of earthquakes in Guerrero, and how they vary along the trench, from the state of Jalisco to the state of Chiapas. The average differences are largest for thrust events occurring close to the trench, and for events in Michoacán. The differences are greater on average for large earthquakes than for small. There is a trade-off between the distance from the trench and timing, suggesting a poor resolution of these parameters, due to the lack of stations the Pacific Ocean. We attribute the differences in locations to systematic patterns in the velocity structure of the mantle, with consistently fast paths to the northeast and relatively slow paths towards the southwest.

Estimation of Damping Correction Factors Using Duration Defined by the Standard Deviation of Phase Difference

The damping correction factors (DCFs) to convert the 5% damping acceleration response spectra to those for other damping levels are computed for the records of 13 Japanese earthquakes. Their correlation with the standard deviation of phase difference ( σ) is also investigated in ten frequency bands. The σ-DCF relations obtained are found to be very similar across the different types of earthquakes. Further, regression analysis suggests that for damping ratios of 1% and 2%, with the increase in σ, the DCFs increase in low-frequency bands (up to 4–5 Hz), whereas they decrease in higher frequency bands. On the other hand, for damping ratios of more than 5%, with the increase in σ, the DCFs decrease in low-frequency bands (up to 1 Hz), whereas the opposite tendency is observed in higher frequency ranges. This research also discusses the applicability of the σ-DCF relations to design ground motion simulation.

Operational modal analysis of a long-span suspension bridge under different earthquake events

Structural health monitoring (SHM) has gained in popularity in recent years since it can assess the performance and condition of instrumented structures in real time and provide valuable information to the asset\'s manager and owner. Operational modal analysis plays an important role in SHM and it involves the determination of natural frequencies, damping ratios and mode shapes of a constructed structure based on measured dynamic data. This paper presents the operational modal analysis and seismic response characterization of the Tsing Ma Suspension Bridge of 2,160 m long subjected to different earthquake events. Three kinds of events, i.e., short-distance, middle-distance and long-distance earthquakes are taken into account. A fast Bayesian modal identification method is used to carry out the operational modal analysis. The modal properties of the bridge are identified and compared by use of the field monitoring data acquired before and after the earthquake for each type of the events. Research emphasis is given on identifying the predominant modes of the seismic responses in the deck during short-distance, middledistance and long- istance earthquakes, respectively, and characterizing the response pattern of various structural portions (deck, towers, main cables, etc.) under different types of earthquakes. Since the bridge is over 2,000 m long, the seismic wave would arrive at the tower/anchorage basements of the two side spans at different time instants. The behaviors of structural dynamic responses on the Tsing Yi side span and on the Ma Wan side span under each type of the earthquake events are compared. The results obtained from this study would be beneficial to the seismic design of future long-span bridges to be built around Hong Kong (e.g., the Hong Kong-Zhuhai-Macau Bridge).

Study on Effects of Sea Ice on Nonlinear Seismic Responses of Single-Column Pier Subject to Different Types of Earthquakes

The seismic response analysis model of a single-column pier surrounded by sea ice was established and it analyzed the nonlinear seismic response of the pier subject to different types of earthquakes. The results show that the maximum seismic responses of the pier occur when the mass of sea ice is about 5000~10000 ton, which should be used to design a pier. When the sea ice is considered, the curvature ductility demand coefficient，the maximum displacement and the maximum residual displacement of the pier are several times than those corresponding to without sea ice, and the M-Ø hysteretic curves of the cross-section of the pier subject to earthquakes present downfallen ‘S’ form significantly and the deformability and energy dissipation capability of the pier drop remarkably.

Evaluation of plastic energy dissipation capacity of steel beams suffering ductile fracture under various loading histories

AbstractThe energy dissipation capacity of a structure is a very important index that indicates the structural performance in energy‐based seismic design. This index depends greatly on the structural components that form the whole system. Owing to the wide use of the strong‐column weak‐beam strength hierarchy where steel beams dissipate the majority of earthquake input energy to the structures, it is necessary to evaluate the energy dissipation capacity of the beams. Under cyclic loadings such as seismic effects, the damage of the beams accumulates. Therefore, loading history is known to be the most pivotal factor influencing the deformation capacity and energy dissipation capacity of the beams. Seismic loadings with significantly different characteristics are applied to structural beams during different types of earthquakes and there is no unique appropriate loading protocol that can represent all types of seismic loadings. This paper focuses on the effects of various loading histories on the deformation capacity and energy dissipation capacity of the beams. Cyclic loading tests of steel beams were performed. In addition, some experimental results from published tests were also collected to form a database. This database was used to evaluate the energy dissipation capacity of steel beams suffering from ductile fracture under various loading histories. Copyright © 2011 John Wiley &amp; Sons, Ltd.

Geometric Spreading Functions and Modeling of Volcanic Zones for Strong-Motion Attenuation Models Derived from Records in Japan

Abstract Attenuation models derived from recorded ground motions are still important elements of probabilistic seismic hazard studies. Engineers use empirical attenuation models to derive the displacement demand for a site of interest from an earthquake at a given location. Many attenuation models have been published for different parts of the world and for different types of earthquakes. Most models have a simple function of constant or magnitude-dependent geometric spreading, and seldom consider well-known seismological effects such as Moho reflection for shallow crustal earthquakes, multiple travel paths and constructive interference for subduction earthquakes, and special characteristics of volcano zones. The reason for not accounting for such effects may be the desire for simplicity in the attenuation functional forms for engineering applications and a lack of records from which to reliably identify these effects quantitatively. In this article, a large set of strong-motion records obtained from dense recording networks in Japan is used to derive geometric attenuation functional form and a possible manner to model the effect of volcanic zones. A liberal approach is taken to introduce a relatively large number of parameters that can account for known seismological effects while retaining a fairly simple attenuation functional form, based on analyses of residuals from simple models similar to those published previously. Preliminary results are reported here, together with the proposed geometric attenuation function forms and plausible explanation of the physical process that leads to the proposed geometric attenuation functions. The proposed model shows a large increase in the maximum likelihood from the random effects methodology, the elimination of bias in the distribution of residuals with respect to source distance, and much improved fitting for well-recorded earthquakes.

Near-Source Released Energy in Relation to Fracture Energy on Earthquake Faults

The near-source energy released on a fault is estimated through the strain energy change and the fracture energy from the results of kinematic waveform inversion and dynamic modeling for two different types of earthquakes: a shallow crustal earthquake, the 2000 Tottori, Japan ( M w 6.6) earthquake, and an in-slab event, the 1999 Oaxaca, Mexico ( M w 7.5) earthquake. The procedure incorporates the spatial distribution of slip, critical slip-weakening distance, stress drop, and strength excess. The results show that the near-source energy density estimated over major asperities on the fault is nearly the same for the two earthquakes, while the fracture energy on the in-slab fault is appreciably larger than that for the crustal fault, suggesting higher strength in the in-slab fault zone. The near-source released energy on major asperities is significantly larger than the fracture energy in the two earthquakes.