Artigos de revistas: "Seismic instability"

1

Bernal, Dionisio. "Instability of buildings during seismic response". Engineering Structures 20, n.º 4-6 (abril de 1998): 496–502. http://dx.doi.org/10.1016/s0141-0296(97)00037-0.

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Rodríguez-Ochoa, Rafael, Farrokh Nadim, José M. Cepeda, Michael A. Hicks e Zhongqiang Liu. "Hazard analysis of seismic submarine slope instability". Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards 9, n.º 3 (3 de julho de 2015): 128–47. http://dx.doi.org/10.1080/17499518.2015.1051546.

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Zhang, Jin, Yanguo Wang, David C. Nobes, Guangnan Huang e Hongxing Li. "Deep seismic reflection data interpretation using balanced filtering method". GEOPHYSICS 82, n.º 5 (1 de setembro de 2017): N43—N49. http://dx.doi.org/10.1190/geo2016-0061.1.

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Inverse [Formula: see text] filtering can perform energy compensation and phase correction of seismic reflection data, but it has an instability problem due to its high-pass characteristics. Although improved methods, such as gain-limited inverse [Formula: see text] filtering and stabilized inverse [Formula: see text] filtering, overcome the instability to some extent, they are not suitable for compensating deep seismic reflection events with weak energy. Focusing on the enhancement of deep seismic events, we have developed a balanced filtering method based on the ratio of the phase-compensated signal to its analytic signal counterpart. The method is insensitive to the depth of seismic records, and it can make shallow and deep seismic records visible simultaneously. When tested on synthetic data and real seismic data, compared with other methods, the balanced filtering method improves the amplitude strength of the deep reflection events and the continuity of shallow and deep seismic events effectively, which makes the deep reflection data easier to interpret.

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Du, Wen Feng, Fu Dong Yu e Zhi Yong Zhou. "Dynamic Stability Analysis of K8 Single-Layer Latticed Shell Structures Suffered from Earthquakes". Applied Mechanics and Materials 94-96 (setembro de 2011): 52–56. http://dx.doi.org/10.4028/www.scientific.net/amm.94-96.52.

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Aiming at the dynamic stability of the K8 single-layer latticed shell structures, it was carried out the dynamic stability analysis based on the finite element method(FEM) in this paper. The dynamic responses of the structure are calculated using the FEM and the B-R rule is applied to determine the dynamic instability critical loads. Results show that the dynamic instability is prone to take place in the K8 single-layer latticed shell structures under the severe seismic load and the dynamic instability critical seismic wave peak value is about 0.7g. The location of instability starts from the intersection between the third circular members and the radial members, then it spreads abroad until the structure collapses.

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Wadas, S. H., S. Tschache, U. Polom e C. M. Krawczyk. "Ground instability of sinkhole areas indicated by elastic moduli and seismic attributes". Geophysical Journal International 222, n.º 1 (20 de abril de 2020): 289–304. http://dx.doi.org/10.1093/gji/ggaa167.

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SUMMARY Elastic moduli derived from vertical seismic profiles (VSPs) and 2-D SH-wave reflection seismic profiles are used to characterize mechanical properties of rocks in sinkhole areas. VP and VS were used to calculate the Poisson’s ratio and the dynamic shear modulus. The study shows that 2-D shear wave reflection seismics is suited to depict the heterogeneities of the subsurface induced by subsurface erosion. Low shear wave velocities of ca. 120–350 m s–1 and low shear strength values between 25 and 250 MPa are identified for the subsurface erosion horizon that consists of soluble Permian evapourites and the disturbed overlying deposits. These low values are a result of cavities and fractures induced by dissolution, creating unstable zones. In compliance with the shear modulus the Poisson’s ratio derived from the VSPs shows values of 0.38–0.48 for both the presumed subsurface erosion horizon, and the deposits above. This is a further indicator of reduced underground stability. In the VSPs, anomalies of the shear modulus and the Poisson’s ratio correlate with low electrical resistivities of less than 10 Ωm from borehole logs, indicating high conductivity due to fluid content. Further investigation reveals a conversion of S-to-P wave for the subsurface erosion horizon, which is probably the result of dipping layers and an oriented fracture network. Seismic attribute analysis of the 2-D sections shows strong attenuation of high frequencies and low similarity of adjacent traces, which correlate with the degree of subsurface erosion induced wave disturbance of the underground.

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Nyland, E., e Qing Li. "Analysis of seismic instability of the Vancouver Island lithoprobe transect". Canadian Journal of Earth Sciences 23, n.º 12 (1 de dezembro de 1986): 2057–67. http://dx.doi.org/10.1139/e86-190.

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Seismic refraction and reflection surveys and gravity measurements over Vancouver Island, British Columbia, Canada, can constrain a finite-element model of the geodynamics of the subduction zone. Stress estimates obtained from this model have been combined with rock failure criteria to yield a probability measure of seismic risk that assumes seismic events start from a dilute distribution of Griffith cracks. The results are in agreement with the observed seismicity and lead to the suggestion that the dominant mechanism of this oceanic plate subduction zone is gravitational ridge push and mantle convection.

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Cui, Fang Peng, Yue Ping Yin, Rui Lin Hu e Jin Qing Yu. "Failure Mechanisms of the Landslides Triggered by the 2008 Wenchuan Earthquake, China". Advanced Materials Research 594-597 (novembro de 2012): 1864–68. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.1864.

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Taking the landslides triggered by the 2008 Wenchuan Earthquake as examples, their dynamic responses with different epicenter distances due to single and combined action with regionality and spatial heterogeneity of the Primary and Secondary waves were simulated by applying the Universal Distinct Element Code software. The results shows that the slope suffered from the combined action between P and S waves appears instability prior to the slope under single action of P wave. With the epicenter distance increasing, the key controlling factor resulting in the slope failure varies from the combined seismic action between P and S waves to the single seismic action of the P wave. As for the formation mechanism of slope instability, coupled action between the vertical and horizontal seismic forces results in the slope dynamic failure with key action varying from the vertical to the horizontal one. Finally, the initial instability originates always at slope shoulder due to the peak ground acceleration amplification effect and the variation trend of the slope mechanical parameters on its fracturing of the seismic action.

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Orlando, Luciana. "Multidisciplinary Approach to a Recovery Plan of Historical Buildings". International Journal of Geophysics 2011 (2011): 1–12. http://dx.doi.org/10.1155/2011/258043.

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The paper emphasizes the advantages of employing multiple data techniques—geology, GPS, surveys of cracking, boreholes, seismic refraction and electrical resistivity tomography—to image the shallow stratigraphy and hypothesize the cause of instability of an urban area. The study is focused on the joint interpretation of the crack pattern, topographic monitoring and the features of the underground, to define the area affected by instability and the direction of ground motion with the objective to advance a hypothesis on the cause of the instability of the area and to depict the main features. Borehole stratigraphies for a univocal interpretation of the lithology of electrical and seismic data and electrical resistivity tomography to constrain the interpretation of the lateral velocity variations and thickness of seismic bedrock were used. The geophysical surveys reveals to be complementary in the depicting of underground features. The study is approached at small and medium scale.

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Taurbekova, A. Ә., О. Zh Mamyrbaev, K. Zh Doshtaev e Т. К. Eginbaykyzy. "HYDRODYNAMIC INSTABILITY MECHANISM PROCESS FOR ASSESSMENT SEISMIC ACTIVITY". SERIES PHYSICO-MATHEMATICAL 4, n.º 348 (28 de dezembro de 2023): 268–89. http://dx.doi.org/10.32014/2023.2518-1726.234.

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Xue, Zongan, Yanyan Ma, Shengjian Wang, Huayu Hu e Qingqing Li. "A Multi-Task Learning Framework of Stable Q-Compensated Reverse Time Migration Based on Fractional Viscoacoustic Wave Equation". Fractal and Fractional 7, n.º 12 (10 de dezembro de 2023): 874. http://dx.doi.org/10.3390/fractalfract7120874.

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Q-compensated reverse time migration (Q-RTM) is a crucial technique in seismic imaging. However, stability is a prominent concern due to the exponential increase in high-frequency ambient noise during seismic wavefield propagation. The two primary strategies for mitigating instability in Q-RTM are regularization and low-pass filtering. Q-RTM instability can be addressed through regularization. However, determining the appropriate regularization parameters is often an experimental process, leading to challenges in accurately recovering the wavefield. Another approach to control instability is low-pass filtering. Nevertheless, selecting the cutoff frequency for different Q values is a complex task. In situations with low signal-to-noise ratios (SNRs) in seismic data, using low-pass filtering can make Q-RTM highly unstable. The need for a small cutoff frequency for stability can result in a significant loss of high-frequency signals. In this study, we propose a multi-task learning (MTL) framework that leverages data-driven concepts to address the issue of amplitude attenuation in seismic records, particularly when dealing with instability during the Q-RTM (reverse time migration with Q-attenuation) process. Our innovative framework is executed using a convolutional neural network. This network has the capability to both predict and compensate for the missing high-frequency components caused by Q-effects while simultaneously reconstructing the low-frequency information present in seismograms. This approach helps mitigate overwhelming instability phenomena and enhances the overall generalization capacity of the model. Numerical examples demonstrate that our Q-RTM results closely align with the reference images, indicating the effectiveness of our proposed MTL frequency-extension method. This method effectively compensates for the attenuation of high-frequency signals and mitigates the instability issues associated with the traditional Q-RTM process.

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Kang, Kai, Andrey Ponomarev, Oleg Zerkal, Shiyuan Huang e Qigen Lin. "Shallow Landslide Susceptibility Mapping in Sochi Ski-Jump Area Using GIS and Numerical Modelling". ISPRS International Journal of Geo-Information 8, n.º 3 (19 de março de 2019): 148. http://dx.doi.org/10.3390/ijgi8030148.

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The mountainous region of Greater Sochi, including the Olympic ski-jump complex area, located in the northern Caucasus, is always subjected to landslides. The weathered mudstone of low strength and potential high-intensity earthquakes are considered as the crucial factors causing slope instability in the ski-jump complex area. This study aims to conduct a seismic slope instability map of the area. A slope map was derived from a digital elevation model (DEM) and calculated using ArcGIS. The numerical modelling of slope stability with various slope angles was conducted using Geostudio. The Spencer method was applied to calculate the slope safety factors (Fs). The pseudostatic analysis was used to compute Fs considering seismic effect. A good correlation between Fs and slope angle was found. Combining these data, sets slope instability maps were achieved. Newmark displacement maps were also drawn according to empirical regression equations. The result shows that the static safety factor map corresponds to the existing slope instability locations in a shallow landslide inventory map. The seismic safety factor maps and Newmark displacement maps may be applied to predict potential landslides of the study area in the case of earthquake occurrence.

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Humar, J., M. Mahgoub e M. Ghorbanie-Asl. "Effect of second-order forces on seismic response". Canadian Journal of Civil Engineering 33, n.º 6 (1 de junho de 2006): 692–706. http://dx.doi.org/10.1139/l05-119.

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In a building structure subjected to seismic forces, the gravity loads acting through the lateral displacements lead to additional shears and moments. This is generally referred to as the P–Δ effect; it tends to reduce the capacity of the structure to resist the seismic forces and may lead to instability. It has been suggested that an increase in structural strength, in stiffness, or in both would mitigate the P–Δ effect and ensure stability of the structure. It is shown here that instability results when the P–Δ effect causes the stiffness of the structure to become negative in the post-yield range, in which case increasing the strength, the stiffness, or both does not ensure stability. In a single-storey structure, stability can be ensured if there is sufficient strain hardening that the post-yield stiffness is positive even in the presence of the P–Δ effect. For a multistorey building the vulnerability of the structure to P–Δ instability can be judged by obtaining a pushover curve. It is shown that as long as the maximum displacement produced by the design earthquake lies in the region of positive slope of the pushover curve, the structure will remain stable.Key words: seismic response, P–Δ effect, dynamic instability, stability coefficient, amplification factor, pushover analysis, nonlinear analysis.

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13

Holt, Rob, e Andy Lubrano. "Stabilizing the phase of onshore 3D seismic data". GEOPHYSICS 85, n.º 6 (1 de novembro de 2020): V473—V479. http://dx.doi.org/10.1190/geo2019-0695.1.

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When present, surface-consistent (shot and/or receiver) phase instability will generate surface-consistent time shifts that are at least partially removed from seismic data when surface-consistent residual statics corrections are applied. The phase instability will not be fully corrected and lingers undetected in the data throughout the remainder of the processing workflow. After processing finishes, seismic interpreters often need to apply laterally varying phase rotations to tie their onshore 3D seismic data to synthetic seismograms, before starting detailed stratigraphic interpretation projects. We have developed and tested a new surface-consistent seismic processing workflow that can be applied to increase the phase stability of our seismic data. It is run after the final pass of conventional surface-consistent residual shot and receiver statics corrections have been applied to optimally align the seismic traces. The phase stability corrections are estimated from an additional pass of surface-consistent residual shot and receiver statics corrections that are calculated on the phase-independent seismic trace envelopes. We demonstrate the application of the workflow using synthetic and real seismic data. We gained confidence that the workflow was performing as expected after we intentionally phase rotated a small subset of the shots and receivers in our seismic test data sets and observed that the workflow corrected these intentionally phase-rotated traces with a high level of accuracy.

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14

Ma, Tian Zhong, e Yan Peng Zhu. "Seismic Strengthening Methods and Analysis of Instability of Gravity Retaining Walls". Advanced Materials Research 971-973 (junho de 2014): 2141–46. http://dx.doi.org/10.4028/www.scientific.net/amr.971-973.2141.

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Using the frame supporting structure of pre-stressed anchor bolt seismic strengthening technology reinforced the instability of gravity retaining wall. Earth pressure of retaining wall in seismic reinforcement after shall take between active and static earth pressure for the form of the distribution . In this paper, based on the limit equilibrium theory, and the whole stability for retaining walls is analysis, the theoretical formula of the stability safety factor between stability against slope and overturning safety factor is derived. By calculation and comparative analysis with an example, the stability safety factor of gravity retaining wall with introducing this strengthening technology is improved obviously. Keywords: frame anchor structure; seismic strengthening; anti-slip and anti-overturning; stability coefficient;

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15

Yuan, Qingteng, Ming Xiao, Ci Kong e Kaicheng Wang. "Seismic Response and Security Assessment of Cross-Fault Hydraulic-Tunnel Lining Structures". Buildings 13, n.º 9 (15 de setembro de 2023): 2348. http://dx.doi.org/10.3390/buildings13092348.

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The foundation of a seismic safety assessment of cross-fault hydraulic tunnels is an acceptable and accurate seismic response. A dynamic contact force algorithm that may take into consideration the interaction between the fault–surrounding rock–lining structure was devised in light of the contact characteristics of various media in cross-fault hydraulic tunnels under seismic activity. A quantitative instability criterion using a relative displacement ratio as the criterion was devised based on the cusp catastrophe model. By using the cross-fault hydraulic tunnel of the Lawa Hydropower Station as an example, it was possible to evaluate and assess the impacts of four working circumstances on the seismic response of the tunnel lining structure. The findings demonstrated that the lining haunch exhibited stronger stress and displacement responses when subjected to seismic activity. The consideration of fault–surrounding rock–lining interaction exacerbated the displacement and stress seismic responses of the lining structure. The haunch, bottom arch, and top arch of the lining’s characteristic parts—which ranged in size from large to small—responded more seismically as peak ground acceleration rose. Applying the aforementioned instability criterion, the haunch, bottom arch, and top arch of the liner structure could withstand maximum peak ground accelerations of 0.10 g, 0.20 g, and 0.35 g, respectively. The aforementioned technique offers a fresh perspective on how to evaluate the seismic response and seismic safety of the tunnel’s lining structure, and the study’s findings can serve as a guide for seismic design.

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Han, Jing Jing, Bao Xian Liu e Dong Liang Zhang. "Stability Analysis of S-RMS under Seismic Loading". Advanced Materials Research 261-263 (maio de 2011): 1336–40. http://dx.doi.org/10.4028/www.scientific.net/amr.261-263.1336.

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Earthquake is one of the main geological disasters that cause slope instability. The stability analysis of soil-rock mixture slope under earthquake is made with FLAC3D in this paper. According to finding the shear strain concentrated deformation zone and the size of the displacement, they can help us to find the possible instability of the scope and location. The study result shows that the slope is stable in the natural state and certain displacement would occur in the potential slide mass of the slope under earthquake, and this must be taken into serious consideration in practical engineering.

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Rollo, Fabio, e Sebastiano Rampello. "Probabilistic assessment of seismic-induced slope displacements: an application in Italy". Bulletin of Earthquake Engineering 19, n.º 11 (5 de junho de 2021): 4261–88. http://dx.doi.org/10.1007/s10518-021-01138-5.

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AbstractEarthquake-induced slope instability is one of the most important hazards related to ground shaking, causing damages to the environment and, often, casualties. Therefore, it is important to assess the seismic performance of slopes, especially in the near fault regions, evaluating the permanent displacements induced by seismic loading. This paper applies a probabilistic approach to evaluate the seismic performance of slopes using an updated database of ground motions recorded during the earthquakes occurred in Italy. The main advantage of this approach is that of accounting for the aleatory variability of both ground motions and prediction of seismic-induced displacements of slopes. The results are presented in terms of hazard curves, showing the annual rate of exceedance of permanent slope displacement evaluated using ground motion data provided by a standard probabilistic hazard analysis and a series of semi-empirical relationships linking the permanent displacements of slopes to one or more ground motion parameters. The procedure has been implemented on a regional scale to produce seismic landslide hazard maps for the Irpinia district, in Southern Italy, characterised by a severe seismic hazard. Seismic landslide hazard maps represent a useful tool for practitioners and government agencies for a regional planning to identify and monitor zones that are potentially susceptible to earthquake-induced slope instability, thus requiring further detailed, site-specific studies.

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Cano, Pablo A., e Ali Imanpour. "Evaluation of AISC Seismic Design Methods for Steel Multi-Tiered Special Concentrically Braced Frames". Engineering Journal 57, n.º 3 (30 de setembro de 2020): 193–214. http://dx.doi.org/10.62913/engj.v57i3.1166.

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Steel multi-tiered concentrically braced frames (MT-CBFs) are commonly used in North America as a lateral load resisting system of tall single-story buildings. Past studies show that MT-CBF columns designed in accordance with the 2010 AISC Seismic Provisions are prone to buckling due to a high axial compression force combined with in-plane bending moments caused by the nonuniform distribution of inelastic brace deformations along the frame height. Special design provisions have been introduced in the 2016 AISC Seismic Provisions to address flexural demands imposed on MT-CBF columns and prevent column instability. In this paper, the seismic design methods for multi-tiered special concentrically braced frames are evaluated using the nonlinear finite element analysis method. A two-tiered special concentrically braced frame was then created, and nonlinear static and dynamic analyses were performed to evaluate the seismic performance of both frames. Analysis results confirmed that the inelastic deformations in the frame designed using the 2010 requirements are not uniformly distributed but rather concentrated in one of the tiers and cause column instability under large story drifts, whereas, the 2016 design method significantly improves the distribution of inelastic deformation along the height of the frame and prevents column instability. Furthermore, it was found that the 2016 AISC Seismic Provisions accurately estimate the axial load but overestimate the in-plane flexural demands and underestimates the out-of-plane flexural demand. Nonetheless, the overestimation of in-plane flexure demands results in acceptable strength capacity even though out-of-plane flexural demands is underestimated.

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Bažant, Zdeněk P., e Milan Jirásek. "Softening-Induced Dynamic Localization Instability: Seismic Damage in Frames". Journal of Engineering Mechanics 122, n.º 12 (dezembro de 1996): 1149–58. http://dx.doi.org/10.1061/(asce)0733-9399(1996)122:12(1149).

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Cordier, Atrick P., Avid D. Mainprice e Jed Leigh Mosenfelder. "Mechanical instability near the stishovite-CaCl2 phase transition: implications for crystal preferred orientations and seismic properties". European Journal of Mineralogy 16, n.º 3 (7 de junho de 2004): 387–99. http://dx.doi.org/10.1127/0935-1221/2004/0016-0387.

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Wayih, Nchini Livinus, Mabel Nechia Wantim e Samuel Ndonwi Ayonghe. "Geotechnical Assessment of Seismic Vulnerability in the Built Environment of Fako Division, South West Region of Cameroon". Journal of Geography, Environment and Earth Science International 28, n.º 8 (30 de julho de 2024): 100–115. http://dx.doi.org/10.9734/jgeesi/2024/v28i8801.

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Introduction: Volcanic earthquakes may trigger severe hazards with considerable impact on the natural and built environment and the surrounding population. Aim: Evaluate the geotechnical characteristics of soils in Fako division to estimate their seismic vulnerability and recommend suitable stabilization techniques to enhance the safety and resilience of built environments. Place and Duration of Study: This study was conducted over a period of 12 months beginning from June 2022 to May 2023. Methodology: It employed a multi-criteria geotechnical approach, involving soil sampling, laboratory analysis, and seismic risk analysis. Soil samples collected from various locations within the study area, were subjected to laboratory tests to determine their plasticity (Atterberg limits) and load-bearing capacity (California Bearing Ratio - CBR). Historical data analysis and seismic hazard mapping were used to assess seismic vulnerability which helped to identify highly susceptible and unstable areas that may require engineered interventions. Results: The findings revealed significant variations in soil plasticity and load-bearing capacity, correlating with observed settlement and instability issues in the region. Historical seismic events, highlighted significant structural damage in areas with high plasticity and low CBR values, underscoring the necessity for robust soil stabilization measures (geotechnical interventions) to mitigate seismic risks and enhance the resilience and safety of structures, reducing the risk of settlement and instability within the Mount Cameroon area, particularly Fako Division.

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Wang, Zehao, Defeng Zheng, Zhongde Gu, Xingsen Guo e Tingkai Nian. "A Methodology to Evaluate the Real-Time Stability of Submarine Slopes under Rapid Sedimentation". Journal of Marine Science and Engineering 12, n.º 5 (14 de maio de 2024): 823. http://dx.doi.org/10.3390/jmse12050823.

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Rapid sedimentation is widely recognized as a crucial factor in initiating the instability of submarine slopes. Once the slope fails, the subsequent landslide poses a significant threat to the safety of underwater infrastructures and potentially leads to severe damage to seabed pipelines, offshore foundations, and oil and gas exploitation wells. However, there is currently a lack of numerical methods to effectively assess the real-time stability of submarine slopes under rapid sedimentation. This study firstly employs a calibrated finite element (FE) model-change approach to reproduce the rapid sedimentation processes and proposes a concise method to calculate the safety factors for the real-time stability of sedimenting submarine slopes. Further, a parametric analysis is carried out to evaluate the effect of varying sedimentation rates on slope stability, and the critical sedimentation rate is numerically solved. Moreover, the effect of seismic events with different occurring times on the stability of rapidly sedimenting slopes is investigated in depth, and the most critical seismic loading pattern among various acceleration combinations is achieved. The results indicate that the presence of weak layers during sedimentation is a critical factor contributing to slope instability. The introduced rate of decrease in the safety factor proves valuable in assessing slope safety over a specific period. As the occurrence time of seismic events is delayed, the seismic resistance of the slope decreases, increasing the likelihood of shallower sliding surfaces. The findings offer insights into the mechanisms by which rapid sedimentation influences the stability of submarine slopes and provide valuable insights for predicting the potential instability of rapidly sedimenting slopes under specific seismic activity levels.

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Xiaowu, Pu, Wang Lanmin, Wang Ping, Chai Shaofeng e Xu Shiyang. "A Method for Quantitative Evaluation of Seismic Stability of Loess Slope Based on the Shaking Table Model Test". Shock and Vibration 2021 (3 de dezembro de 2021): 1–13. http://dx.doi.org/10.1155/2021/5587489.

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The large-scale shaking table model test, which can directly reproduce the process of slope instability and failure, is an important technical means for the prediction and evaluation of slope seismic stability. However, up to now, the systematic slope stability evaluation method based on the shaking table slope model test has not been established, which limits the application of the expensive shaking table model test in slope seismic design. Therefore, the slope stability evaluation method based on the model test needs to be developed and innovated. In this research, through three loess slope model tests with different rainfall, according to the change law of the peak value of transfer function spectrum, combined with the macrodestructive characteristics of the slope model, an accurate calculation method of the critical instability acceleration of the slope is proposed. Based on the behavior similarity theory, for the shaking table model test of slope whose soil cohesion cannot meet the similarity ratio, the reduction method of applying the critical instability acceleration obtained from the model test to prototype slope is proposed. Based on first-order natural frequency and damping ratio extracted from the TF spectrum curve, a calculation method for the stability factor Fs of loess slope based on the shaking table model test is proposed, and the stability factors of loess slope under the action of different seismic ground motion would be quantitatively calculated. The above methods provide another effective way for qualitative prediction and evaluation of seismic stability of loess slope.

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Sun, Dun Ben, e Qing Wen Ren. "Catastrophic Analysis of Seismic Response of Gravity Dam Sliding along Base Surface". Advanced Materials Research 311-313 (agosto de 2011): 2164–68. http://dx.doi.org/10.4028/www.scientific.net/amr.311-313.2164.

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For the instability problem of gravity dam sliding along base surface, cubic nonlinear constitutive model of soft material in base surface is adopted, which is usually expressed by Weibull model. Dynamic Equations of dam sliding along base surface is established. By means of catastrophe theory, the jumping and hysteresis phenomena of the vibration amplitude of the dam is analyzed, the parameter range of stable region in which amplitude doesn’t happen catastrophe is given and the factors which cause amplitude instability are discussed. The results obtained in the paper are of significant value for understanding the sliding instability mechanism of gravity dam under earthquake, as well as guiding the design of gravity dams.

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Li, Jie, e Jun Xu. "Dynamic Stability and Failure Probability Analysis of Dome Structures Under Stochastic Seismic Excitation". International Journal of Structural Stability and Dynamics 14, n.º 05 (junho de 2014): 1440001. http://dx.doi.org/10.1142/s021945541440001x.

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The intrinsic relationship between deterministic system and stochastic system is profoundly revealed by the probability density evolution method (PDEM) with introduction of physical law into the stochastic system. On this basis, stochastic dynamic stability analysis of single-layer dome structures under stochastic seismic excitation is firstly studied via incorporating an energetic physical criterion for identification of dynamic instability of dome structures into PDEM, which yields to sample stability (stable reliability). However, dynamic instability is not identical to structural failure definitely, where strength failure can be experienced not only in the stable structure but also when the structure is out of dynamic stability. It is practically feasible to decouple the stochastic dynamic response of dome structures to be a stable one and an unstable one according to the generalized density evolution equation (GDEE). Consequently, the global failure probability can be investigated separately based on the corresponding independent stochastic response. For unstable failure probability assessment, the failure probability is the unstable probability if the dome's failure is attributed to instability, whereas inverse absorbing is firstly implemented to get rid of the stochastic response before instability and a complementary process is filled in the safe domain immediately to finally assess the probability of strength failure after dynamic instability.

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Havenith, H. B., A. Strom, D. Jongmans, A. Abdrakhmatov, D. Delvaux e P. Tréfois. "Seismic triggering of landslides, Part A: Field evidence from the Northern Tien Shan". Natural Hazards and Earth System Sciences 3, n.º 1/2 (30 de abril de 2003): 135–49. http://dx.doi.org/10.5194/nhess-3-135-2003.

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Abstract. Landslides triggered by strong earthquakes often caused most of the global damage and most of all casualties related to the events, such as shown by the M = 7.7 Peru earthquake in 1970, by the M = 7.6 El Salvador earthquake in 2001 or by the M = 7.4 Khait (Tajikistan) earthquake in 1949. The obvious impact of a landslide on the population is directly related to its movement. Yet, prediction of future failure potential and hence future risk to population is necessary in order to avoid further catastrophes and involves the analyses of the origin of seismic instability. The seismic landslide potential is mainly determined by the interaction between the regional seismic hazard and local geological conditions. At a local scale, seismic factors interfering with geological conditions can produce site-specific ground motions. The influence of such Site Effects on instability is the principal topic of this paper, which is divided into two parts, A and B. The present Part A is concerned with the correlation of field data with observed instability phenomena. Field data were obtained on mainly three landslide sites in the Northern Tien Shan Mountains in Kyrgyzstan, Central Asia. Geophysical prospecting, earthquake recordings, geological observation, trenching and geotechnical tests were the main investigation tools. The collected information gives an insight in the geological background of the slope failure and allows us to roughly infer failure mechanisms from field evidence. A detailed analysis of the susceptibility of a mechanism to specific geological conditions will be shown in Part B.

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Zania, Varvara, Yiannis Tsompanakis e Prodromos N. Psarropoulos. "Seismic Distress and Slope Instability of Municipal Solid Waste Landfills". Journal of Earthquake Engineering 12, n.º 2 (13 de fevereiro de 2008): 312–40. http://dx.doi.org/10.1080/13632460701574605.

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dos Santos, Filipe Amarante, Corneliu Cismasiu e Francisco Braz Fernandes. "Cyclic Instability of Shape-Memory Alloys in Seismic Isolation Systems". International Journal of Structural Glass and Advanced Materials Research 2, n.º 1 (1 de janeiro de 2018): 82–95. http://dx.doi.org/10.3844/sgamrsp.2018.82.95.

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Hariri-Ardebili, M. A., e S. M. Seyed-Kolbadi. "Seismic cracking and instability of concrete dams: Smeared crack approach". Engineering Failure Analysis 52 (junho de 2015): 45–60. http://dx.doi.org/10.1016/j.engfailanal.2015.02.020.

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Hori, Y., e T. Kato. "Earthquake-Induced Instability of a Rotor Supported by Oil Film Bearings". Journal of Vibration and Acoustics 112, n.º 2 (1 de abril de 1990): 160–65. http://dx.doi.org/10.1115/1.2930108.

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The effect of seismic waves on the stability of a Jeffcott rotor supported by oil film bearings is investigated by calculating loci of the centers of the journal and the disk using the Runge-Kutta-Gill method. It will be shown that a linearly stable rotor can become unstable under a strong artificial shock and a real seismic wave, if it is running at speeds above twice the first critical speed, which is close to the natural frequency of the rotor. Thus, it will be pointed out that the linear analysis is insufficient to examine the stability of a rotor-bearing system if the rotor is operated above twice the critical speed and a strong shock such as due to an earthquake is expected.

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Sun, Lin, Junchao Li e Haoyu Lin. "Dynamic Stability Finite Difference Time Domain Analysis of Landfill Based on Hypergravity Test". Applied Sciences 14, n.º 7 (3 de abril de 2024): 3006. http://dx.doi.org/10.3390/app14073006.

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Earthquakes impact the stability of municipal solid waste (MSW) landfills, especially those with high water levels, and may further lead to disastrous landslides. Numerical analysis offers an efficient and cost-effective way to study the seismic stability of a landfill. In this study, the finite difference nonlinear analysis method was employed to meticulously evaluate the dynamic response of landfills under varying water levels and seismic intensities. The analysis was guided by the seismic instability and centrifuge test outcomes. The rationality of the computational model was verified by examining the responses of acceleration and pore pressure. Subsequently, the time history curve of the dynamic safety factor was derived from the dynamic response of landfills. The results indicated that a landfill was more susceptible to large earthquake effects, and its stability decreased as the water level rose, with the safety factor decreasing to a critical point under the coupling effect of strong earthquakes and high water levels. In contrast, the stability of the landfill with low water levels was good under weak earthquake conditions, with only a slight decrease in the safety factor observed. The seismic stability of a landfill was significantly influenced by both accumulative deformation and negative excess pore pressure. A certain degree of hysteresis in the landfill’s instability was also observed compared to the earthquake loading process. The time history curve of the safety factor can offer a comprehensive insight into seismic stability under diverse conditions. Additionally, future research efforts are needed to better determine the values of strength parameters of MSW in seismic analysis.

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Liang, Hui, Jin Tu, Shengshan Guo, Jianxin Liao, Deyu Li e Shiqi Peng. "Seismic fragility analysis of a High Arch Dam-Foundation System based on seismic instability failure mode". Soil Dynamics and Earthquake Engineering 130 (março de 2020): 105981. http://dx.doi.org/10.1016/j.soildyn.2019.105981.

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Liang, Hui, Shengshan Guo, Yifu Tian, Jin Tu, Deyu Li e Chunli Yan. "Probabilistic Seismic Analysis of the Deep Sliding Stability of a Concrete Gravity Dam-Foundation System". Advances in Civil Engineering 2020 (8 de dezembro de 2020): 1–10. http://dx.doi.org/10.1155/2020/8850398.

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There are various uncertainties in the design, construction, and operation of dams. These uncertainties have an important impact on the seismic response and seismic safety evaluation of concrete dams. In this research, a typical nonoverflow monolith of a concrete gravity dam is selected as a case study for the sliding stability analysis. Based on the analysis and demonstration of parameter sensitivity of friction coefficients and cohesion and their influence on the deep antisliding stability of the dam-foundation system, the probabilistic seismic analysis of a gravity dam-foundation system is carried out through Monte Carlo analysis with a large sample number. Damage levels are defined based on the sliding instability failure mode along with the corresponding threshold values of the damage index. Thus, seismic fragility analysis is investigated, and seismic fragility curves are obtained for the vulnerability assessment under earthquake hazards. The overall seismic stability of the gravity dam is evaluated, which provides the basis for the seismic safety evaluation in the probabilistic framework.

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Zhuge, Hanqing, Xianglong Zheng, Fangyuan Song e Zhanzhan Tang. "Fiber Model Considering the Local Instability Effect and Its Application to the Seismic Analysis of Eccentrically Compressed Steel Piers". Applied Sciences 12, n.º 12 (8 de junho de 2022): 5838. http://dx.doi.org/10.3390/app12125838.

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To propose a seismic response calculation model for eccentrically compressed steel piers that can consider the local instability effect and horizontal bidirectional earthquake actions, in-plane and out-of-plane pseudo-static numerical simulation and bidirectional seismic response analysis are performed to study the applicability of the improved fiber model. The comparison results with the refined hybrid-element model show that the improved fiber model can accurately simulate the hysteretic performance of eccentrically compressed steel piers in the in-plane or out-of-plane directions and can be used to calculate the structural seismic requirements under the bidirectional action of rarely met earthquakes.

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Buijze, Loes, Peter A. J. van den Bogert, Brecht B. T. Wassing, Bogdan Orlic e Johan ten Veen. "Fault reactivation mechanisms and dynamic rupture modelling of depletion-induced seismic events in a Rotliegend gas reservoir". Netherlands Journal of Geosciences 96, n.º 5 (dezembro de 2017): s131—s148. http://dx.doi.org/10.1017/njg.2017.27.

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AbstractUnderstanding the mechanisms and key parameters controlling depletion-induced seismicity is key for seismic hazard analyses and the design of mitigation measures. In this paper a methodology is presented to model in 2D the static stress development on faults offsetting depleting reservoir compartments, reactivation of the fault, nucleation of seismic instability, and the subsequent fully dynamic rupture including seismic fault rupture and near-field wave propagation. Slip-dependent reduction of the fault's strength (cohesion and friction) was used to model the development of the instability and seismic rupture. The inclusion of the dynamic calculation allows for a closer comparison to field observables such as borehole seismic data compared to traditional static geomechanical models. We applied this model procedure to a fault and stratigraphy typical for the Groningen field, and compared the results for an offset fault to a fault without offset. A non-zero offset on the fault strongly influenced the stress distribution along the fault due to stress concentrations in the near-fault area close to the top of the hanging wall and the base of the footwall. The heterogeneous stress distribution not only controlled where nucleation occurred within the reservoir interval, but also influenced the subsequent propagation of seismic rupture with low stresses inhibiting the propagation of slip. In a reservoir without offset the stress distribution was relatively uniform throughout the reservoir depth interval. Reactivation occurred at a much larger pressure decrease, but the subsequent seismic event was much larger due to the more uniform state of stress within the reservoir. In both cases the models predicted a unidirectional downward-propagating rupture, with the largest wave amplitudes being radiated downwards into the hanging wall. This study showed how a realistic seismic event could be successfully modelled, including the depletion-induced stressing, nucleation, dynamic propagation, and wave propagation. The influence of fault offset on the depletion-induced stress is significant; the heterogeneous stress development along offset faults not only strongly controls the timing and location of a seismic slip, but also influences the subsequent rupture size of the dynamic event.

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Han, Junguo, Yuanmin Yang, Muzi Du e Rui Pang. "Seismic Reliability Analysis of an Excavation Slope Based on Direct Probability Integral Method". Mathematical Problems in Engineering 2024 (30 de março de 2024): 1–10. http://dx.doi.org/10.1155/2024/7012424.

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China, situated in the circum-Pacific seismic belt, experiences frequent seismic activity and faces diverse geological conditions, making structural stability of paramount importance, especially under seismic conditions. The majority of current earthquake generation methods do not consider the nonstationary nature of earthquakes. This paper introduces a spectral representation-random function model for generating nonstationary earthquakes, effectively simulating stochastic seismic ground motion. Furthermore, traditional slope stability analysis methods are deterministic and incapable of providing probabilistic assessments of slope instability. Therefore, this paper proposes a unified framework for static and dynamic structural reliability analysis based on the direct probability integration method, quantifying the impact of stochastic seismic ground motion on the dynamic reliability of slope stability. Finally, the proposed methods are applied to an excavation slope in Nanjing, using sliding displacement and safety factors as evaluation criteria to study the reliability of the slope under the influence of stochastic seismic events.

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Tremblay, Robert, e Laure Poncet. "Improving the Seismic Stability of Concentrically Braced Steel Frames". Engineering Journal 44, n.º 2 (30 de junho de 2007): 103–16. http://dx.doi.org/10.62913/engj.v44i2.906.

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An analytical study was performed to examine the seismic stability of multi-story concentrically braced steel frames. The building height was varied from 4 to 16 stories and three braced frame systems were studied: conventional braced frames, buckling-restrained braced frames, and dual buckling-restrained braced frames. All structures were designed according to Canadian seismic provisions. Different force modification factors were used and both the equivalent static load procedure and the modal response spectrum analysis were considered in design. P-delta effects were accounted for in the design of some of the buildings. The performance of the various structures is evaluated and compared by means of incremental dynamic analysis. The results show that the potential for instability for conventional braced frames is higher for taller structures or when the design loads are reduced. Tall buckling-restrained braced frames were also found to be prone to dynamic instability. Dual buckling-restrained braced frames exhibit a more robust response and represent a promising solution for tall braced steel frames.

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Zhao, Yan, Ningbo Mao e Zhiming Ren. "A stable and efficient approach of Q reverse time migration". GEOPHYSICS 83, n.º 6 (1 de novembro de 2018): S557—S567. http://dx.doi.org/10.1190/geo2018-0022.1.

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Amplitude energy attenuation and phase distortion of seismic waves caused by formation viscoelasticity reduce the resolution of reverse time migration (RTM) images. Q-RTM often is used to compensate the attenuation effects and improve the resolution of seismic imaging. However, serious high-frequency noise and tremendous amplitude will be produced during the wavefield extrapolation of Q-RTM, resulting in its inability to be imaged. Many Q-RTM algorithms solve the problem of instability through low-pass filtering in the wavenumber domain, but the method is less efficient in computation and has a truncation effect in the wavefield. We have developed a stable and efficient Q-RTM method, in which a regularization term was introduced into the viscoacoustic wave equation to suppress the high-frequency noise, and the finite-difference method was used to solve the viscoacoustic wave equation with a regularization term. We used the model example to visually demonstrate the instability of wavefield extrapolation in Q-RTM and compared the effect and computational efficiency of the two stabilization processing methods, low-pass filtering and regularization. Meanwhile, our method is not involved in solving the fractional derivatives by using the pseudo-spectral method, the computational efficiency also can be improved. We tested the Q-RTM approach on a simple layered model, Marmousi model, and real seismic data. The results of numerical examples demonstrated that the Q-RTM method can solve the problem of instability effectively and obtain a higher resolution image with lower computational cost.

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Chai, Xintao, Genyang Tang, Fangfang Wang, Hanming Gu e Xinqiang Wang. "Q-compensated acoustic impedance inversion of attenuated seismic data: Numerical and field-data experiments". GEOPHYSICS 83, n.º 6 (1 de novembro de 2018): R553—R567. http://dx.doi.org/10.1190/geo2017-0499.1.

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Acoustic impedance (AI) inversion is of great interest because it extracts information regarding rock properties from seismic data and has successful applications in reservoir characterization. During wave propagation, anelastic attenuation and dispersion always occur because the subsurface is not perfectly elastic, thereby diminishing the seismic resolution. AI inversion based on the convolutional model requires that the input data be free of attenuation effects; otherwise, low-resolution results are inevitable. The intrinsic instability that occurs while compensating for the anelastic effects via inverse [Formula: see text] filtering is notorious. The gain-limit inverse [Formula: see text] filtering method cannot compensate for strongly attenuated high-frequency components. A nonstationary sparse reflectivity inversion (NSRI) method can estimate the reflectivity series from attenuated seismic data without the instability issue. Although AI is obtainable from an inverted reflectivity series through recursion, small inaccuracies in the reflectivity series can result in large perturbations in the AI result because of the cumulative effects. To address these issues, we have developed a [Formula: see text]-compensated AI inversion method that directly retrieves high-resolution AI from attenuated seismic data without prior inverse [Formula: see text] filtering based on the theory of NSRI and AI inversion. This approach circumvents the intrinsic instability of inverse [Formula: see text] filtering by integrating the [Formula: see text] filtering operator into the convolutional model and solving the inverse problem iteratively. This approach also avoids the ill-conditioned nature of the recursion scheme for transforming an inverted reflectivity series to AI. Experiments on a benchmark Marmousi2 model validate the feasibility and capabilities of our method. Applications to two field data sets verify that the inversion results generated by our approach are mostly consistent with the well logs.

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Fomin, V., e І. Fomina. "CONSTRUCTION OF DYNAMIC INSTABILITY ZONES FOR HIGH STUCTURES UNDER SEISMIC IMPACT". Mechanics And Mathematical Methods 2, n.º 2 (dezembro de 2020): 42–50. http://dx.doi.org/10.31650/2618-0650-2020-2-2-42-50.

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Seismic impacts create the possibility of parametric resonances, i.e. the possibility of the appearance of intense transverse vibrations of structure elements (in particular, of high-rise structures) from the action of periodic longitudinal forces. As a design model of a high-rise structure, a model is used which adopted in the calculation of high-rise structures for seismic effects, - a weightless vertical rod (column) rigidly restrained at the base with a system of concentrated masses (loads) located on it (Fig. 1). By solving the differential equation of the curved axis influence function for a rod is constructed by means of which influence coefficients are determined for the rod points, in which the concentrated masses are situated. These coefficients are elements of the compliance matrix . Next, the elements of the stiffness matrix are determined by inverting the matrix . Using a diagonal matrix of the load masses and matrix a system of differential equations of free vibrations of a mechanical system, consisting of concentrated masses, is constructed, and the frequencies and forms of these vibrations are determined. From the vertical component of the seismic impact, its most significant part is picked out in the form of harmonic vibrations with the predominant frequency of the impact. Column vibrations are considered in a moving coordinate system, the origin of which is at the base of the column. The forces acting on the points of the mechanical system (concentrated masses) are added by the forces of inertia of their masses associated with the translational motion of the coordinate system. The forces of the load weights and forces of inertia create longitudinal forces in the column, periodically depending on time. Further, the integro-differential equation of the dynamic stability of the rod, proposed by V. V. Bolotin in [8], is written. The solution to this equation is sought in the form of a linear combination of free vibration forms with time-dependent factors. Substitution of this solution into the integro-differential equation of dynamic stability allows it to be reduced to a system of differential equations with respect to the mentioned above factors with coefficients that periodically depend on time. For some values of the vertical component parameters of the seismic action, namely the frequency and amplitude, the solutions of these equations are infinitely increasing functions, i.e. at these values of the indicated parameters, a parametric resonance arises. These values form regions in the parameter plane called regions of dynamic instability. Next, these regions are being constructed. A concrete example is considered.

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An, Ning, Huidong Zhang, Xinqun Zhu e Fei Xu. "A Hybrid Approach for the Dynamic Instability Analysis of Single-Layer Latticed Domes with Uncertainties". International Journal of Structural Stability and Dynamics 21, n.º 06 (22 de março de 2021): 2150082. http://dx.doi.org/10.1142/s0219455421500826.

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Currently, there is no unified criterion to evaluate the failure of single-layer latticed domes, and an accurate nonlinear time-history analysis (NTHA) is generally required; however, this does not consider the uncertainties found in practice. The seismic instability of domes subjected to earthquake ground motions has not been thoroughly investigated. In this paper, a new approach is developed to automatically capture the instability points in the incremental dynamic analysis (IDA) of single-layer lattice domes by integrating different efficient and robust methods. First, a seismic fragility analysis with instability parameters is performed using the bootstrap calibration method for the perfect dome. Second, based on the Sobol sequence, the quasi-Monte Carlo (QMC) sampling method is used to efficiently calculate the failure probability of the dome with uncertain parameters, in which the truncated distributions of random parameters are considered. Third, the maximum entropy principle (MEP) method is used to improve the computational efficiency in the analyses of structures with uncertainties. Last, the uncertain interval of the domes is determined based on the IDA method. The proposed method has been used to investigate the instability of single-layer lattice domes with uncertain parameters. The results show that it can determine the probability of structural failure with high efficiency and reliability. Additionally, the limitations of the proposed method for parallel computation are discussed.

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Zhang, Changjun, e Tadeusz J. Ulrych. "Seismic absorption compensation: A least squares inverse scheme". GEOPHYSICS 72, n.º 6 (novembro de 2007): R109—R114. http://dx.doi.org/10.1190/1.2766467.

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The problem of instability plagues conventional inverse [Formula: see text] filtering. We formulate the deabsorption problem as an inverse problem in terms of least squares and impose regularization by means of Bayes’ theorem. The solution is iterative and nonparametric and returns a reflectivity that has been constrained to be sparse. The inverse scheme is tested on both synthetic and real data and the results obtained demonstrate the viability of the approach.

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Dadfar, Behrang, M. Hesham El Naggar e Miroslav Nastev. "Quantifying exposure of linear infrastructures to earthquake-triggered transverse landslides in permafrost thawing slopes". Canadian Geotechnical Journal 54, n.º 7 (julho de 2017): 1002–12. http://dx.doi.org/10.1139/cgj-2017-0076.

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Seismic shaking can cause slope instability in otherwise relatively stable permafrost terrains. In addition, rapid ice melting in low-permeability fine-grained soils can lead to excess pore-water pressure build-up and cause instability in slopes even at small angles. This study addresses the active-layer detachment (ALD) slope instability hazard and develops a systematic risk assessment framework for existing and future linear infrastructures, such as energy pipelines, bridges, and roads traversing permafrost regions. Mild slopes, with average gradient of 7°, are considered in this study as the most representative of actual field conditions. The potential for earthquake-triggered ALD is analytically quantified. State-of-the-art ALD morphological statistics for northern Canada are combined with seismic slope stability analyses to determine (i) the probability of linear infrastructure exposure to permanent ground deformations (PGDs) caused by ALD and (ii) the extent of the potential PGD that the linear infrastructure may be subjected to. The Monte Carlo technique is applied to simulate and assess the sensitivity of the model to parameters such as earthquake magnitude and source-to-site distance. Findings from this study can be used to evaluate the vulnerability of linear infrastructures exposed to the ALD hazard.

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Bogomolov, L. M., e V. N. Sychev. "Fundamental for self-developing processes model and problems of its application to earthquakes prediction in the Far East region". Geosystems of Transition Zones 5, n.º 2 (2021): 138–52. http://dx.doi.org/10.30730/gtrz.2021.5.2.138-145.145-152.

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Seismic activation in the period of foreshocks (prior to the mainshock) described by the model of self-developing processes (SDP) is possibly a manifestation of explosive instability of low frequency straining waves in metastable medium. To highlight so nontrivial relationship of continuous wave motions and discrete seismic events flow is a goal of this narrative. Thus, the rationale of the SDP model (the equation, in reality) has been modified, which is of importance in relevance with the article by the Malyshevs in the current issue (A.I. Malyshev, L.K. Malysheva. Precedent-extrapolation estimate of the seismic hazard in the Sakhalin and South Kurils region) which is to improve the seismic hazard estimates by means of this model. A new way to reveal the very beginning of blow-up regime after quasi-stationary one is proposed.

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Bassetti, Matteo, Andrea Belleri e Alessandra Marini. "Dynamic instability of axially loaded elements: General considerations and seismic loading". Journal of Constructional Steel Research 170 (julho de 2020): 106088. http://dx.doi.org/10.1016/j.jcsr.2020.106088.

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Beresnev, I. A., e V. N. Nikolaevskiy. "A model for nonlinear seismic waves in a medium with instability". Physica D: Nonlinear Phenomena 66, n.º 1-2 (junho de 1993): 1–6. http://dx.doi.org/10.1016/0167-2789(93)90217-o.

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Carotti, A., e R. Chiappulini. "Brake systems for protecting large structures from seismic or aerodynamic instability". Engineering Structures 16, n.º 8 (novembro de 1994): 625–36. http://dx.doi.org/10.1016/0141-0296(94)90048-5.

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Dong, Longjun, Huanyu Zhu, Fang Yan e Shuijin Bi. "Risk Field of Rock Instability using Microseismic Monitoringdata in Deep Mining". Sensors 23, n.º 3 (23 de janeiro de 2023): 1300. http://dx.doi.org/10.3390/s23031300.

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With the gradual depletion of surface resources, rock instability caused by deep high stressand mining disturbance seriously affects safe mining. To create effective risk management, a rockinstability risk field model using microseismic monitoring data is proposed in this study. Rockinstability risk was presented visually in 3D visualization. The in-situ microseismic monitoringdata was collected and analyzed to make calculation of peak ground velocity (PGV), peak groundacceleration (PGA), energy flux, energy and seismic moment. Indicator weights of PGV, PGA, energyflux are confirmed by using the analytic hierarchy process (AHP) to calculate risk severity. The Copulafunction is then used to solve the joint probability distribution function of energy and seismic moment.Then the spatial distribution characteristics of risk can be obtained by data fitting. Subsequently, thethree-dimensional (3D) risk field model was established. Meanwhile, the established risk field isverified by comparing monitoring data without disturbance and the blasting data with disturbance.It is suggested that the proposed risk field method could evaluate the regional risk of rock instabilityreasonably and accurately, which lays a theoretical foundation for the risk prediction and managementof rock instability in deep mining.

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Saritaş, Fevzi, Idris Bedirhanoglu, Arova Konak e Mehmet Salih Keskin. "Effect of Seismic Isolation on the Performance of High-Rise Buildings with Torsional Instability". Sustainability 15, n.º 1 (20 de dezembro de 2022): 36. http://dx.doi.org/10.3390/su15010036.

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Seismic bearings have been used to mitigate the harmful effect of the earthquakes. Torsion mode, one of the most important irregularities, generally increases the shear forces to the vertical members such as columns and shear walls in turn this may results in brittle failure of the reinforced concrete (RC) members. Accordingly, it is vital to eliminate the torsion failure mode or switch to the higher modes with lower mass contribution. This study has evaluated the seismic performance of a high-rise building with torsion mode through push-over analysis including nonlinear time history analyses. The damage conditions of RC structural members are defined considering the Eurocode definitions and general performance assessments of the building have been evaluated accordingly. Lead rubber bearings have been used for base isolation system. By using enough number of rubber bearings, the dominant torsion mode (first free vibration mode) has been shifted to higher modes. Various earthquake records have been used in non-linear dynamic analysis to evaluate the positive effects of the bearings. The results revealed that proper arrangement of rubber bearings in structural plan of ground floor can effectively improve dynamic behavior of a high rise building with torsional instability to achieve better seismic performance.

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Zaruma, Santiago R., e Larry A. Fahnestock. "Seismic Stability of Buckling-Restrained Braced Frames". Key Engineering Materials 763 (fevereiro de 2018): 924–31. http://dx.doi.org/10.4028/www.scientific.net/kem.763.924.

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Buckling Restrained Braced Frames (BRBFs) are widely used as seismic force resisting systems due to their ductility and energy dissipation. However, because of the modest overstrength and relatively low post-yielding stiffness, BRBFs subjected to seismic loading may be susceptible to concentrations of story drift and global instability triggered by P-∆ effects. Due to the use of simplistic methods that are based on elastic stability, current code design provisions do not address seismic stability rigorously and do not consider the particular inelastic response of a system. Design strategies are needed to prevent undesirable seismic response in BRBFs, such as drift concentration and large residual drift. This study used the FEMA P-695 Methodology to evaluate the response of current U.S. code-based BRBF designs and to study the effect on seismic stability of three potential enhancements: strong-axis orientation for BRBF columns, gravity column contribution, and a BRBF-SMRF dual system. Results from nonlinear static and dynamic analyses allowed assessment of seismic behavior. Results from collapse performance evaluation quantify the improvement that is achieved with each alternative and provide a means of comparison.

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