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1
Cui, Fengkun, Linlin Song, Xingyu Wang, Mian Li, Peng Hu, Shuwen Deng, Xinyue Zhang, and Huihui Li. "Seismic Fragility Analysis of the Aging RC Columns under the Combined Action of Freeze–Thaw Cycles and Chloride-Induced Corrosion." Buildings 12, no. 12 (December 14, 2022): 2223. http://dx.doi.org/10.3390/buildings12122223.
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The combined action of freeze–thaw cycles and chloride-induced corrosion are generally recognized as one of the main causes of the degradation of the mechanical properties and seismic performance of reinforced concrete (RC) structures in the northern frozen coastal regions. To investigate the degradation mechanisms of the seismic performance of RC columns subjected to the combined action of freeze–thaw cycles and chloride-induced corrosion, the impact of freeze–thaw cycles on the chloride diffusion coefficient of concrete was studied through concrete deterioration tests and theoretical analysis. This paper proposed a time-dependent deterioration model for RC columns, which is suitable to consider the combined action of freeze–thaw cycles and chloride-induced deterioration. The proposed deterioration model could be applied to the investigations of time-dependent seismic performance and the seismic fragility of RC columns. Based on the established deterioration model, this paper proposed a time-dependent seismic fragility analysis framework for the aging RC columns, considering the combined action of freeze–thaw cycles and chloride-induced corrosion. In addition, a representative three-span RC continuous T-shaped girder bridge that is located in the high-latitude northern frozen coastal regions of China was taken as the case study, and the time-dependent seismic fragility analysis of RC columns was conducted considering the involved uncertainties in geometric parameters, the deterioration mechanisms of the materials, and ground motions. The time-dependent seismic fragility curves of RC columns were obtained at different service time points. The results indicated that the combined action of freeze–thaw cycles and chloride-induced deterioration had a significant influence on the time-dependent seismic responses of the deteriorating RC columns. Under the combined action of freeze–thaw cycles and chloride-induced corrosion, when the RC bridge was in service for 75 years, the stirrup strength decreased by 3.88% and the cross-sectional area decreased by 30.03%. The peak stress of the confined concrete decreased by 52.1% and its peak strain increased by 12.2 times, respectively. Moreover, the time-dependent seismic fragilities of the aging RC columns under different damage states exhibited a nonlinear increase as the service life increased.
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Cui, Fengkun, Guangzhu Guan, Long Cui, Mian Li, Shuwen Deng, and Huihui Li. "Seismic Fragility Assessment of RC Columns Exposed to the Freeze-Thaw Damage." Buildings 13, no. 1 (January 3, 2023): 126. http://dx.doi.org/10.3390/buildings13010126.
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Freeze–thaw damage is one of the primary causes deteriorating the seismic resistance of reinforced concrete (RC) structures. This paper proposed a freeze–thaw damage deterioration model for C30 concrete, and it can be employed to study the time-varying seismic performance of aging RC columns. Next, this study developed a seismic fragility analysis framework for deteriorating RC columns considering the effect of freeze–thaw damage. Considering the geometric parameters of the case-study bridge, the deterioration characteristics of material, and the uncertainties involved in structural modeling and ground motions, a probabilistic seismic fragility analysis on aging RC columns was conducted. The results indicate that the influence of freeze–thaw damage cannot be ignored in studying the seismic performance of aging RC structures. The seismic fragilities of deteriorating RC columns shown a nonlinear increase trend as the increased of freeze–thaw cycles and severity of the damage state. In the early stage of freeze–thaw cycles, the seismic fragilities of RC columns increased slowly. However, the closer to the later stage of freeze–thaw cycles, the more significant of the increase in the seismic fragilities of the columns.
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Malhotra, Praveen K., Paul E. Senseny, Antonio C. Braga, and Roger L. Allard. "Testing Sprinkler-Pipe Seismic-Brace Components." Earthquake Spectra 19, no. 1 (February 2003): 87–109. http://dx.doi.org/10.1193/1.1543160.
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The design codes and standards (e.g., UBC, IBC, NFPA-13) estimate the amplitude of the seismic load in sprinkler-pipe braces, but they do not specify the number of cycles for which this load must be resisted by various components of pipe braces. Because the components can fail in low-cycle fatigue, the number of load cycles must be considered in establishing the strength of the brace components. The first part of this study deals with determining the number of cycles for which a component must resist its rated capacity. Strong-motion records from 18 strongly shaken buildings were incorporated into a low-cycle fatigue model to develop a test criterion for measuring the seismic strength of brace components. In the second part of this study, a series of tests were conducted to gain insight into the cyclic behavior of brace components. Finally, a test protocol was established to measure the seismic strength of brace components. With some modifications, the protocol can be applied to many other nonstructural components.
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Muratalieva, Zhazgul, and Aiymjan Omuralieva. "Monitoring the dynamics of seismicity within the Kemin-Chilik zone, generating M≥8 earthquakes." Russian Journal of Seismology 2, no. 4 (December 16, 2020): 51–62. http://dx.doi.org/10.35540/2686-7907.2020.4.05.
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The dynamics of seismic processes at the junction of the Tien Shan mountain building area and the Kazakh shield is presented in the paper. It is noted that the Tien Shan’s lithosphere over thrusts the Kazakh Shield’s lithosphere, and the Kazakh Shield’s lithosphere under thrusts beneath the Tien Shan’s lithosphere based on the seismic tomographic and seismotectonic data. Low-velocity heterogeneity is distinguished at the junction of these lithospheres, under where a low-velocity anomaly flow is assumed in the mantle. Marginal (active structures of the Ili basin, Zaili mountain range), and middle (active structures of the Kemin, Chilik basins, Kungei mountain range) subzones with characteristic seismicity and seismic regimes are formed here. Seismogenic zones are distinguished (from north to south): Predzaili, Kemin-Chilik, Predkungei. Powerful earthquakes with M>8 occur in the Kemin-Chilik seismogenic zone (about 250 km long and up to 25 km wide), and earthquakes with M=7-8 - in the Predza-ili and Predkungei seismogenic zones. The dynamics of the earthquakes’ sequence is predetermined by the dynamics of the hierarchy of faults and blocks in the junction zone. The sequence of earthquakes is expressed by the hierarchy of seismic cycles. Seismic activation period, a peak of seismic activation, a period of seismic activation’s decay, and seismic calm period are distinguished in every cycle. Strong earthquakes take place in a first-order cycle with a long period, significant and small earthquakes - in cycles with corresponding short periods. The seismicity level of the study area is determined by the trajectory of the seismic cycles’ association. Dynamic segmentation and dynamic sectorization, vectors of seismic activity directed from the east and west to the highly compressed central part of the region are noted in the spatial and temporal distribution of earthquakes at the junction of the Tien Shan and the Kazakh shield.
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Viete, Daniel R., Bradley R. Hacker, Mark B. Allen, Gareth G. E. Seward, Mark J. Tobin, Chris S. Kelley, Gianfelice Cinque, and Andrew R. Duckworth. "Metamorphic records of multiple seismic cycles during subduction." Science Advances 4, no. 3 (March 2018): eaaq0234. http://dx.doi.org/10.1126/sciadv.aaq0234.
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Wu, Jieqiong, Jian Zhang, Bo Diao, Shaohong Cheng, and Yinghua Ye. "Hysteretic Behavior of Eccentrically Loaded Reinforced Air-Entrained Concrete Columns under Combined Effects of Freeze-Thaw Cycles and Seawater Corrosion." Advances in Civil Engineering 2018 (July 19, 2018): 1–10. http://dx.doi.org/10.1155/2018/3931791.
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Besides service loads, reinforced concrete structures in cold coastal seismic regions are subjected to multiple attacks of freeze-thaw cycles and seawater corrosion as well as the earthquake struck. An experimental study was conducted to investigate the seismic response of eccentrically loaded reinforced air-entrained concrete columns under alternative actions of freeze-thaw cycles and chloride corrosion. Results show that, after 300 times of freeze-thaw cycles alternated with 100 times of seawater immersion, the hysteretic behavior of the eccentrically loaded columns manifested an apparent asymmetric pattern. Under forward cyclic load, the existence of larger eccentric load rendered the reduction of the ultimate load and the ductility of a column by up to 20.3% and 46.05%, respectively, but it had a positive effect if reverse cyclic load was applied. The presence of eccentric load could have a considerable impact on the seismic behavior of reinforced air-entrained concrete columns served in an aggressive environment.
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Kwiatek, Grzegorz, T. H. W. Goebel, and Georg Dresen. "Seismic moment tensor andbvalue variations over successive seismic cycles in laboratory stick-slip experiments." Geophysical Research Letters 41, no. 16 (August 20, 2014): 5838–46. http://dx.doi.org/10.1002/2014gl060159.
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Gandelli, Emanuele, Dario De Domenico, and Virginio Quaglini. "Cyclic engagement of hysteretic steel dampers in braced buildings: a parametric investigation." Bulletin of Earthquake Engineering 19, no. 12 (July 1, 2021): 5219–51. http://dx.doi.org/10.1007/s10518-021-01156-3.
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AbstractHysteretic steel dampers have been effectively used to improve the seismic performance of framed buildings by confining the dissipation of seismic energy into sacrifical, replaceable devices which are not part of the gravity framing system. The number of cycles sustained by the dampers during the earthquake is a primary design parameter, since it can be associated to low-cycle fatigue, with ensuing degradation of the mechanical properties and potential failure of the system. Current standards, like e.g. the European code EN 15129, indeed prescribe, for the initial qualification and the production control of hysteretic steel dampers, cyclic tests in which the devices are assessed over ten cycles with amplitude equal to the seismic design displacement dbd. This paper presents a parametric study focused on the number of effective cycles of the damper during a design earthquake in order to assess the reliability of the testing procedure proposed by the standards. The study considers typical applications of hysteretic steel dampers in low and medium-rise steel and reinforced concrete framed buildings and different ductility requirements. The results point out that the cyclic engagement of the damper is primarily affected by the fundamental period of the braced building and the design spectrum, and that, depending on these parameters, the actual number of cycles can be substantially smaller or larger that recommended by the standards. A more refined criterion for establishing the number of cycles to be implemented in testing protocols is eventually formulated.
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Wang, Fred P., Jiachun Dai, and Charles Kerans. "Modeling dolomitized carbonate‐ramp reservoirs: A case study of the Seminole San Andres unit—Part II, Seismic modeling, reservoir geostatistics, and reservoir simulation." GEOPHYSICS 63, no. 6 (November 1998): 1876–84. http://dx.doi.org/10.1190/1.1444480.
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In part I of this paper, we discussed the rock‐fabric/petrophysical classes for dolomitized carbonate‐ramp rocks, the effects of rock fabric and pore type on petrophysical properties, petrophysical models for analyzing wireline logs, the critical scales for defining geologic framework, and 3-D geologic modeling. Part II focuses on geophysical and engineering characterizations, including seismic modeling, reservoir geostatistics, stochastic modeling, and reservoir simulation. Synthetic seismograms of 30 to 200 Hz were generated to study the level of seismic resolution required to capture the high‐frequency geologic features in dolomitized carbonate‐ramp reservoirs. At frequencies <70 Hz, neither the high‐frequency cycles nor the rock‐fabric units can be identified in seismic data because the tuning thickness of seismic data is much greater than the average thickness of high‐frequency cycles of 6 m. At frequencies >100 Hz, major high‐porosity and dense mudstone units can be better differentiated, while the rock‐fabric units within high‐frequency cycles can be captured at frequencies higher than 200 Hz. Seismic inversion was performed on the 30- to 200-Hz synthetic seismograms to investigate the level of seismic resolution required to recover the high‐resolution inverted impedance logs. When seismic data were noise free, wavelets were known and sampling rates were high; deconvolution techniques yielded perfect inversion results. When the seismic data were noisy, the inverted reflectivity profiles were poor and complicated by numerous high‐frequency spikes, which can be significantly removed using the moving averaging techniques. When wavelets were not known, the predictive deconvolution gave satisfactory inversion results. These results suggest that interwell information required for reservoir characterization can be recovered from low‐frequency seismic data by inversion. Outcrop data were collected to investigate effects of sampling interval and scale‐up of block size on geostatistical parameters. Semivariogram analysis of outcrop data showed that the sill of log permeability decreases and the correlation length increases with an increase of horizontal block size. Permeability models were generated using conventional linear interpolation, stochastic realizations without stratigraphic constraints, and stochastic realizations with stratigraphic constraints. The stratigraphic feature of upward‐shoaling sequences can be modeled in stochastic realizations constrained by the high‐frequency cycles and rock‐fabric flow units. Simulations of a fine‐scale Lawyer Canyon outcrop model were used to study the factors affecting waterflooding performance. Simulation results show that waterflooding performance depends strongly on the geometry and stacking pattern of the rock‐fabric units and on the location of production and injection wells.
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Zhang, Yixin, Shansuo Zheng, Xianliang Rong, Liguo Dong, and Hao Zheng. "Seismic Performance of Reinforced Concrete Short Columns Subjected to Freeze–Thaw Cycles." Applied Sciences 9, no. 13 (July 3, 2019): 2708. http://dx.doi.org/10.3390/app9132708.
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Previous research shows that freeze–thaw cycles represent one of the most dangerous threats to reinforced concrete (RC) structures. However, there is almost no experimental data on the effects of freeze–thaw cycles on the seismic behavior of RC columns showing flexure-shear failure. In this study, three columns with the shear span-to-depth ratio of 2.5 were subjected to different numbers of freeze–thaw cycles (FTCs) and pseudo-static testing. The seismic performance indexes of the specimens were analyzed in terms of hysteretic behavior, skeleton curves, shear deformation, and energy dissipation. The test observations show that the failure patterns of the test columns altered from the flexure dominated to shear dominated, owing to the more severe deterioration in shear capacity induced by freeze–thaw attack than in flexure capacity. The test results also indicate that freeze–thaw cycles significantly decrease the ductility and energy dissipation of test columns, and they increase the contributions of shear deformation to the total deformation.
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Omurbek kyzy, Kanyshai, and Mederbek Omuraliev. "Seismic monitoring of explosions in the Central site of the Kumtor deposit, Tien Shan." Russian Journal of Seismology 2, no. 4 (December 16, 2020): 83–99. http://dx.doi.org/10.35540/2686-7907.2020.4.08.
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Seismic monitoring of explosions was carried out at the local area of the Central site of the Kumtor deposit for January 2017 - January 2018. Velocities of seismic longitudinal and transverse waves, their ratios (VP, VS, VP/VS), maximum amplitudes and their ratios (AP, AS, AS/AP) were studied, and average values with standard deviation values were determined, and hierarchies of cycles are distinguished in their variations in time. It is noted that the ratios of VP, VS, VP/VS reflect the state of the crust medium, small values of VP, VS, VP/VS express possible manifestation of fluids, and large value of the ratio VP/VS – possible manifestation of partial melting, large values of VP, VS – possible manifestation of relatively high pressures. Physical parameters of the medium are estimated: seismic parameter Φ, Poisson's ratio, shear modulus, and bulk modulus. It is established that these physical parameters are dynamic parameters that depend on the frequency of geodynamic processes, namely, in cycles, for example, of the third order with a relatively high frequency, relatively small values of modules (physical parameters of the medium) are observed, and in cycles of the second and first orders with a relatively low frequency, relatively large values of modules are observed. Changes in the values of AP, AS, AS/AP, and the degree of seismic waves’ absorption are predetermined by physical parameters and the state of the medium. Change in the penetration depth of seismic waves from an explosion is noted in the range of about 8-35 km
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Rosenau, Matthias, Fabio Corbi, and Stephane Dominguez. "Analogue earthquakes and seismic cycles: experimental modelling across timescales." Solid Earth 8, no. 3 (May 19, 2017): 597–635. http://dx.doi.org/10.5194/se-8-597-2017.
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Abstract. Earth deformation is a multi-scale process ranging from seconds (seismic deformation) to millions of years (tectonic deformation). Bridging short- and long-term deformation and developing seismotectonic models has been a challenge in experimental tectonics for more than a century. Since the formulation of Reid's elastic rebound theory 100 years ago, laboratory mechanical models combining frictional and elastic elements have been used to study the dynamics of earthquakes. In the last decade, with the advent of high-resolution monitoring techniques and new rock analogue materials, laboratory earthquake experiments have evolved from simple spring-slider models to scaled analogue models. This evolution was accomplished by advances in seismology and geodesy along with relatively frequent occurrences of large earthquakes in the past decade. This coincidence has significantly increased the quality and quantity of relevant observations in nature and triggered a new understanding of earthquake dynamics. We review here the developments in analogue earthquake modelling with a focus on those seismotectonic scale models that are directly comparable to observational data on short to long timescales. We lay out the basics of analogue modelling, namely scaling, materials and monitoring, as applied in seismotectonic modelling. An overview of applications highlights the contributions of analogue earthquake models in bridging timescales of observations including earthquake statistics, rupture dynamics, ground motion, and seismic-cycle deformation up to seismotectonic evolution.
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Kato, Naoyuki. "Simulation of seismic cycles of buried intersecting reverse faults." Journal of Geophysical Research: Solid Earth 106, B3 (March 10, 2001): 4221–32. http://dx.doi.org/10.1029/2000jb900417.
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Xu, Jingling, Luofu Liu, Guiwen Wang, Changchun Zou, and Jin Lai. "Study of sedimentary sequence cycles by well-seismic calibration." Petroleum Science 10, no. 1 (February 7, 2013): 65–72. http://dx.doi.org/10.1007/s12182-013-0251-z.
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Zheng, Shan Suo, Bin Wang, Lei Li, Wei Wang, and Jin Chuan He. "Component Seismic Damage Model for SRHSHPC Joints." Key Engineering Materials 417-418 (October 2009): 705–8. http://dx.doi.org/10.4028/www.scientific.net/kem.417-418.705.
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The deficiency of present damage model is generalized by studying existing references. The mechanical properties of steel reinforced high strength and high performance concrete (SRHSHPC) members under monotonic loading, including the capacity of ultimate deformation, strength, stiffness, etc. are analyzed after the different number of cycles. The reduction factor is introduced, the dynamic variation relationship of ultimate deformation with the number of cycles is obtained, and the merits of existing damage model are utilized, finally the seismic damage model, which is suitable for SRHSHPC beam-column joints, is established. In order to verify the rationality of damage model, Opensees as a nonlinear analysis program is adopted to simulate SRHSHPC joints, the comparison of the numerical analysis results with experimental results shows that the proposed damage model can capture the behaviors of joints very well. The model can, therefore, be used to carry out seismic damage analysis of other SRHSHPC members.
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Meng, Fan Chao, Xiao Ming Yuan, and Hui Xue. "Effect of Loading Amplitude on Soil Deformation under Irregular Waves and Fixed-Number Waves." Applied Mechanics and Materials 256-259 (December 2012): 2015–18. http://dx.doi.org/10.4028/www.scientific.net/amm.256-259.2015.
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Through series of dynamic triaxial tests, the relationships of soil deformations under irregular seismic loading and fixed-number constant amplitude loading are analyzed. The effect of loading amplitudes on the relationships is presented. The results shows: (1) soil deformation under irregular seismic loading obviously differs from that under constant amplitude sinusoidal loading, and the strain history is mainly controlled by the performance of ground motion; (2) if 20 cycles of constant amplitude loading is employed instead of irregular seismic loading to correct residual deformation under real seismic loading, loading amplitudes have no effect on soil deformation under irregular waves and fix-number waves.
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Di Cesare, Antonio, Felice Carlo Ponzo, Nicla Lamarucciola, and Domenico Nigro. "Dynamic Seismic Response of Nonlinear Displacement Dependent Devices versus Testing Required by Codes: Experimental Case Studies." Applied Sciences 10, no. 24 (December 10, 2020): 8857. http://dx.doi.org/10.3390/app10248857.
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Passive energy dissipation systems are one of the most resilient solutions to mitigate the seismic risk of structures. In case of strong motions, they can confine the eventual damages into easily replaceable anti-seismic devices. The performance characteristics of nonlinear displacement dependent devices (NLD) shall be defined by the force-displacement cyclic behavior, as well as the expected number of cycles related to both the duration of the earthquake and to the fundamental frequency of the structural systems. The aims of this paper are the comparison between the dynamic results of two different experimental campaigns performed on NLDs included in dissipative bracing systems and the assessment of the reliability of quasi-static testing procedures proposed by current seismic codes for type tests and factory production control tests. The number of cycles under the design earthquake of hysteretic dampers were experimentally evaluated through shaking table testing. Two experimental case studies of a two-story steel frame and of a three-story post-tensioned timber frame both with bracing systems including flexural steel dampers, hysteretic dampers (HDs), and U-shaped flexural plates (UFPs) respectively, were analyzed. Controlled-displacement tests of NLDs were performed considering quasi-static loading procedures specified by codes. Shaking table tests were carried out considering almost the same seismic sequence composed by a set of seven natural earthquakes at increasing peak ground acceleration (PGA) levels. More than one hundred inelastic cycles were experimentally recorded from dynamic tests before the failure of devices in both cases. In line with American standards testing requirements, the number of cycles at the design PGA level, estimated from shaking table tests and from non-linear dynamic analyses, shows a decreasing trend with the increase of ductility demand.
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Carpinteri, Alberto, and Gianni Niccolini. "Correlation between the Fluctuations in Worldwide Seismicity and Atmospheric Carbon Pollution." Sci 1, no. 1 (September 28, 2018): 2. http://dx.doi.org/10.3390/sci1010002.
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The crucial stages in the geochemical evolution of the Earth’s crust, ocean, and atmosphere could be explained by the assumed low-energy nuclear reactions (LENR) that are triggered by seismic activity. LENR result in the fission of medium-weight elements accompanied by neutron emissions, involving Fe and Ni as starting elements, and C, N, O as resultants. Geochemical data and experimental evidences support the LENR hypothesis. A spectral analysis of the period 1955-2013 shows common cycles between interannual changes in atmospheric CO2 growth rate and global seismic-moment release, whereas the trending behavior of the atmospheric CO2 was in response to the anthropogenic emissions. Assuming a correlation between such seismic and atmospheric fluctuations, the latter could be explained by cycles of worldwide seismicity, which would trigger massively LENR in the Earth’s Crust. In this framework, LENR from active faults could be considered as a relevant cause of carbon formation and degassing of freshly-formed CO2 during seismic activity. However, further studies are necessary to validate the present hypothesis which, at the present time, mainly aims to stimulate debate on the models which regulates atmospheric CO2.
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Carpinteri, Alberto, and Gianni Niccolini. "Correlation between the Fluctuations in Worldwide Seismicity and Atmospheric Carbon Pollution." Sci 1, no. 1 (January 2, 2019): 2. http://dx.doi.org/10.3390/sci1010002.v2.
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The crucial stages in the geochemical evolution of the Earth’s crust, ocean, and atmosphere could be explained by the assumed low-energy nuclear reactions (LENR) that are triggered by seismic activity. LENR result in the fission of medium-weight elements accompanied by neutron emissions, involving Fe and Ni as starting elements, and C, N, O as resultants. Geochemical data and experimental evidences support the LENR hypothesis. A spectral analysis of the period 1955-2013 shows common cycles between interannual changes in atmospheric CO2 growth rate and global seismic-moment release, whereas the trending behavior of the atmospheric CO2 was in response to the anthropogenic emissions. Assuming a correlation between such seismic and atmospheric fluctuations, the latter could be explained by cycles of worldwide seismicity, which would trigger massively LENR in the Earth’s Crust. In this framework, LENR from active faults could be considered as a relevant cause of carbon formation and degassing of freshly-formed CO2 during seismic activity. However, further studies are necessary to validate the present hypothesis which, at the present time, mainly aims to stimulate debate on the models which regulates atmospheric CO2.
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Carpinteri, Alberto, and Gianni Niccolini. "Correlation between the Fluctuations in Worldwide Seismicity and Atmospheric Carbon Pollution." Sci 1, no. 1 (January 2, 2019): 17. http://dx.doi.org/10.3390/sci1010017.
Full textAbstract:
The crucial stages in the geochemical evolution of the Earth’s crust, ocean, and atmosphere could be explained by the assumed low-energy nuclear reactions (LENR) that are triggered by seismic activity. LENR result in the fission of medium-weight elements accompanied by neutron emissions, involving Fe and Ni as starting elements, and C, N, O as resultants. Geochemical data and experimental evidences support the LENR hypothesis. A spectral analysis of the period 1955-2013 shows common cycles between interannual changes in atmospheric CO2 growth rate and global seismic-moment release, whereas the trending behavior of the atmospheric CO2 was in response to the anthropogenic emissions. Assuming a correlation between such seismic and atmospheric fluctuations, the latter could be explained by cycles of worldwide seismicity, which would trigger massively LENR in the Earth’s Crust. In this framework, LENR from active faults could be considered as a relevant cause of carbon formation and degassing of freshly-formed CO2 during seismic activity. However, further studies are necessary to validate the present hypothesis which, at the present time, mainly aims to stimulate debate on the models which regulates atmospheric CO2.
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Gheibi, Emad, and Mohammad Hosein Bagheripour. "Effect of Parameters on Equivalent Number of Cycles Using Nonlinear Seismic Site Response Analysis." Advanced Materials Research 255-260 (May 2011): 2365–69. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.2365.
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The concept of equivalent number of uniform stress cycles, is essential for assessment of soil liquefaction potential. In this regard, various procedures are used to convert random acceleration time history to uniform cycles having amplitude of 0.65 of peak acceleration. Equivalent number of cycles (Neq) defines equivalent energy generated by harmonic loading as that imposed by irregular motion during an earthquake. Neq is assumed to be a function of earthquake magnitude. Over the past years, in accordance with development in methods of soil liquefaction evaluation, various methods have been proposed to determinate equivalent number of cycles. In particular, parameters like site to source distance (r), have been related directly to Neq. In this study, more than 80 earthquake records have been investigated and their Neqs are assessed using energy approach and nonlinear site response analysis. It is shown that equivalent number of cycles is related to earthquake magnitude (M), r and depth of originated signals. Unlike previous methods which result in scatter in output data, current approach has led to more uniform and consistent results for each earthquake.
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Kishida, Tadahiro, and Chi-Chin Tsai. "Seismic Demand of the Liquefaction Potential with Equivalent Number of Cycles for Probabilistic Seismic Hazard Analysis." Journal of Geotechnical and Geoenvironmental Engineering 140, no. 3 (March 2014): 04013023. http://dx.doi.org/10.1061/(asce)gt.1943-5606.0001033.
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Xu, Shanhua, Anbang Li, Zengyang Ji, and Yan Wang. "Seismic performance of reinforced concrete columns after freeze–thaw cycles." Construction and Building Materials 102 (January 2016): 861–71. http://dx.doi.org/10.1016/j.conbuildmat.2015.10.168.
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Adeishvili, Teimuraz, Aleksandar Aleksandrov, and Magdana Jikia. "ON SEISMICSENSITIVITY OF BIOSYSTEMS AND COSMIC CYCLE PERTURBATION." Journal Scientific and Applied Research 6, no. 1 (October 11, 2014): 44–47. http://dx.doi.org/10.46687/jsar.v6i1.139.
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The paper discusses the connections of the occurrences in biosphere with the cosmic seismic activity and cosmic cycles, namely, with the interposition of the sun and the planets. Some relation patterns between the changes of the radon concentration in thermal-mineral waters, the physiological events occurring in and biosystem and cosmic biorhythms have been revealed.
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Santos, A. R. G., T. L. Campante, W. J. Chaplin, M. S. Cunha, M. N. Lund, R. Kiefer, D. Salabert, et al. "Seismic signatures of magnetic activity in solar-type stars observed by Kepler." Proceedings of the International Astronomical Union 13, S340 (February 2018): 225–28. http://dx.doi.org/10.1017/s1743921318001229.
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AbstractThe properties of the acoustic modes are sensitive to magnetic activity. The unprecedented long-term Kepler photometry, thus, allows stellar magnetic cycles to be studied through asteroseismology. We search for signatures of magnetic cycles in the seismic data of Kepler solar-type stars. We find evidence for periodic variations in the acoustic properties of about half of the 87 analysed stars. In these proceedings, we highlight the results obtained for two such stars, namely KIC 8006161 and KIC 5184732.
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Guo, Feng, Changshuan Ji, Shenghua Lai, and Lei Zhang. "A method of establishing high-resolution isochronous stratigraphic framework in 3D seismic data volume." Stratigraphy 20, no. 2 (2023): 143–54. http://dx.doi.org/10.29041/strat.20.2.04.
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The establishment of a high-frequency sequence stratigraphic framework (short-term cycles) is the basis of seismic sedimentology research, which provides a new way to establish a high-resolution isochronous stratigraphic framework using 3D-seismic data. The linear interpolation between reference seismic reflections is used to establish a high-resolution isochronous stratigraphic framework (stratal slices). By carefully calibrating time-depth relationships, a corresponding relationship between short-term cycle (high-frequency cycle) interfaces and stratal slices is created. Five reference seismic reflections correspond to maximum flood surfaces. The results show that 311 isochronous stratal slices are formed in the 90 degree phase of the 3D seismic data set. Reference seismic reflection does not change with frequency. The event axis of reference for isochronous seismic reflection often corresponds to the most obvious isochronous interfaces. This method can establish a high-resolution isochronous stratigraphic framework in areas lacking drilling data in a 3D seismic data set. When geological dating data is available, the stratal slices can be further calibrated to absolute geological time, and a paleogeological map can be constructed from the seismic data set. This case study also illustrates the theoretical and practical significance of this method.
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Martinez, Fernando J., Michael L. Batzle, and André Revil. "Influence of temperature on seismic velocities and complex conductivity of heavy oil-bearing sands." GEOPHYSICS 77, no. 3 (May 1, 2012): WA19—WA34. http://dx.doi.org/10.1190/geo2011-0433.1.
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The joint inversion of seismic and electromagnetic data can be of great use to monitor the steam-assisted production of heavy oils in field conditions. Seismic velocity and complex conductivity laboratory measurements were performed on three heavy oil-bearing sands at confining and pore pressures similar to field conditions. One of the samples (8H) was initially oil-wet and the two other samples (5P-3A and P-1A) were initially water-wet. Low-frequency stress-strain measurements and complex conductivity measurements were performed during two heating cycles (at constant temperature, 10°C steps in the range 20°C–70°C). The temperature was first increased from 20°C–70°C simulating initial stage in a thermal recovery process. During this temperature increase, sample 8H changed to water-wet with a clear irreversible signature on the seismic and electrical data. Then the temperature was decreased and cycled a second time in the temperature range 20°C–70°C. The seismic and complex conductivity responses were found to be identical at each temperature for the temperature decrease of the first heating cycle and the second cycle. For the water-wet samples (5P-3A and P-1A), the compressional and shear velocities decreased with the increase of temperature and the in-phase and quadrature conductivities increased with the temperature with the same temperature sensitivity coefficient ([Formula: see text]). After these two heating cycles, we extracted the heavy oil from sample 8H and additional complex conductivity measurements were performed at different salinities to determine the two Archie’s exponents [Formula: see text] and [Formula: see text]. We found [Formula: see text] for the cementation exponent while the saturation exponent is given by [Formula: see text] when the sand is oil-wet and [Formula: see text] when the rock is water-wet. The power-law exponent for the quadrature conductivity of the water-wet samples is [Formula: see text].
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Lobkovsky, Leopold I., Irina S. Vladimirova, Yurii V. Gabsatarov, and Dmitry A. Alekseev. "Features of the Largest Earthquake Seismic Cycles in the Western Part of the Aleutian Subduction Zone." Geosciences 12, no. 3 (February 24, 2022): 107. http://dx.doi.org/10.3390/geosciences12030107.
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We discussed the peculiarities of the seismic cycle in Aleutian subduction zone, characterized by an oblique subduction setting. It was shown that the orientation of the plate convergence vector relative to the subduction zone axis can have a significant impact on the preparation and occurrence of the largest earthquakes in subduction zones. In particular, from the analysis of the seismic activity occurring in the western part of the Aleutian island arc, it was found that the seismic cycles here are shorter than in the eastern part of the arc. It was revealed that the strongest earthquakes, repeating in the same areas of the western part of the Aleutian subduction zone, differ both in magnitude and length of the fault zone. Taking into account the oblique subduction setting, we proposed the keyboard model of the largest megathrust earthquakes generation as a mechanism potentially capable of explaining the reduction in the seismic cycle duration and noticeable differences in the spatial extent and localization of the fault zones of events with similar magnitudes occurring in the same segment of the western half of the Aleutian subduction zone.
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Xu, C., J. Geoffrey Chase, and Geoffrey W. Rodgers. "Nonlinear Regression Based Health Monitoring of Hysteretic Structures under Seismic Excitation." Shock and Vibration 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/193136.
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This paper presents a health monitoring method using measured hysteretic responses. Acceleration and infrequently measured displacement are integrated using a multirate Kalman filtering method to generate restoring force-displacement hysteresis loops. A linear/nonlinear regression analysis based two-step method is proposed to identify nonlinear system parameters. First, hysteresis loops are divided into loading/unloading half cycles. Multiple linear regression analysis is applied to separate linear and nonlinear half cycles. Preyielding stiffness and viscous damping coefficient are obtained in this step and used as known parameters in the second step. Then, nonlinear regression analysis is applied to identified nonlinear half cycles to yield nonlinear system parameters and two damage indicators: cumulative plastic deformation and residual deformation. These values are closely related to structural status and repair costs. The feasibility of the method is demonstrated using a simulated shear-type structure with different levels of added measurement noise and a suite of ground motions. The results show that the proposed SHM method effectively and accurately identifies physical system parameters with up to 10% RMS added noise. The resulting damage indicators can robustly and clearly indicate structural condition over different earthquake events.
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Kulak, Goeffrey L., D. J. L. Kennedy, Robert G. Driver, and Manoj Medhekar. "Steel Plate Shear Walls—An Overview." Engineering Journal 38, no. 1 (March 31, 2001): 50–62. http://dx.doi.org/10.62913/engj.v38i1.748.
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Steel plate shear walls are an innovative lateral loadresisting system capable of effectively bracing a building against both wind and earthquake forces. The system consists of vertical steel infill plates one story high and one bay wide connected to the surrounding beams and columns. The plates are installed in one or more bays for the full height of a building to form a stiff cantilever wall. North American practice is to use unstiffened plates. Steel plate shear walls are well-suited for new construction, and they offer a relatively simple means for the seismic upgrading of existing steel or concrete structures. Several researchers have conducted tests on single-story and small-scale multistory laboratory specimens. The most significant physical testing has been that of a large-scale four-story, single bay specimen. Tested under controlled cyclic loading to determine its behavior under an idealized severe earthquake event, it endured 30 cycles of loading, including 20 cycles in the inelastic range. It showed excellent ductility and energy dissipation characteristics, and exhibited stable behavior at very large deformations and after many cycles of loading. Both a non-linear finite element model and a plane frame analysis model suitable for design office use are available. The seismic performance of the steel plate shear wall concept has been further evaluated using a hypothetical multi-story building located in Vancouver, Canada. The examination was done in accordance with the National Building Code of Canada. The seismic response is assessed with a linear static analysis and a response spectrum analysis, both standard analysis procedures in seismic design practice. A nonlinear static "pushover"ť analysis was also performed to determine the inelastic static response. The inelastic dynamic response was obtained from nonlinear dynamic time history analyses using a set of appropriately selected earthquake accelerograms.
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Teng, Fei, Yueying Zhang, Weidong Yan, Xiaolei Wang, and Yanfeng Li. "Numerical Simulation of Reinforced Concrete Piers after Seawater Freeze–Thaw Cycles." Coatings 12, no. 12 (November 25, 2022): 1825. http://dx.doi.org/10.3390/coatings12121825.
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The reinforced concrete (RC) piers of offshore bridges inevitably experience seawater freeze–thaw cycles due to the periodic movement of tides in cold climates. The damage caused by seawater freeze–thaw cycles will reduce the durability and mechanical properties of concrete, and then affect the seismic performance of RC piers. The method of seismic performance analysis on RC piers by numerical simulation is gradually emerging because the process of the conventional experiment is relatively complicated, and the heterogeneity and degradation of concrete after seawater freeze–thaw cycles should be considered. In this study, the method of meso-element equivalent and layered modeling was used to simulate a low cyclic loading test on an RC pier after seawater freeze–thaw cycles with ABAQUS software. The numerical simulation results were compared with the experimental results; the deviation value of peak load was not more than 6%, and the deviation value of peak displacement was not more than 10%. The result of the numerical simulation matched well with the experimental results, and the influence of different parameters was analyzed through the practical method of numerical simulation. It can be determined that the peak load decreased by 11%, while the peak displacement increased by 40% after 125 seawater freeze–thaw cycles. In the same 125 freeze–thaw cycles, the peak load increased by 15% and 27% while the axial compression ratio and the longitudinal reinforcement diameter increased. As the stirrup spacing of specimens decreased, the peak load remained unchanged, but the ductility coefficient of the specimens increased by 20%.
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Sheridan, Mattilda, D. Rhodri Johns, Howard D. Johnson, and Sandra Menpes. "The stratigraphic architecture, distribution and hydrocarbon potential of the organic-rich Kyalla and Velkerri shales of the Upper Roper Group (McArthur Basin)." APPEA Journal 58, no. 2 (2018): 858. http://dx.doi.org/10.1071/aj17224.
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Recent exploration studies on the stratigraphic framework, depositional environment and tectonic setting of the Mesoproterozoic Roper Group in the McArthur Basin, have led to an improved understanding of the highly prospective organic-rich shales of the Velkerri and Kyalla Formations. From a review of open-file drill core and well logs, several major regressive–transgressive (R–T) cycles have been identified along with four key facies associations within the Roper Group. The R–T cycles show sedimentary features typical of deposition within a clastic-dominated marine deltaic setting and show marked lateral variation in facies and thicknesses. The lateral thickness variations are particularly noticeable across regional 2D seismic lines. Seismic interpretation and well correlation confirm the extensive and relatively undeformed nature of the Velkerri and Kyalla Formations in the subsurface, they appear thickest in the south-east of the Beetaloo Sub-Basin.
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Cao, Chen, Shan-suo Zheng, Wei-bing Hu, Li-guo Dong, and Xiao-rui Liu. "Seismic Behavior of Reinforced Concrete Frame Joints in Coastal Atmosphere." Advances in Civil Engineering 2020 (March 10, 2020): 1–15. http://dx.doi.org/10.1155/2020/1636539.
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The study aims to research the influence of salt fog corrosion cycles on seismic performance of reinforced concrete (RC) frame beam-column joints in coastal atmosphere. Based on low cyclic loading tests of six RC frame beam-column joint specimens, this study analyses the failure patterns, hysteresis loops, load carrying capacity, displacement, backbone curves, and energy dissipation capacity of corrosion-damaged RC frame beam-column joints. The effect of salt fog corrosion cycles and axial compression ratios are tested repeatedly. The results show that with the same level of axial compression of the frame joint specimens, as the increase of salt fog cycles, the strength, ductility, energy dissipation, bearing capacity, and deformation capacity of joints degenerated to different degrees． When the corrosion level is the same, the stiffness degradation appeared to be more apparent as the increase of axial compression ratio. Then, the behavior degeneration rule of the RC frame beam-column joints is analyzed and formed according to the results of the test; the degeneration restoring force models of corroded RC frame beam-column joints is formed and verified based on Clough’s three-line degenerate restoring force model and the introduction to cyclic degeneration index. The results show that the restoring force model can better describe the hysteresis characteristics of the beam-column joints of corroded RC frames. The research is a theoretical reference for the seismic analysis of the RC frame structure affected by coastal atmospheric environment.
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Telesca, Luciano, Anh Tuan Thai, Dinh Trong Cao, Dinh Trieu Cao, Quoc Van Dinh, and Xuan Bach Mai. "Fractal and Spectral Analysis of Seismicity in the Lai Chau Area (Vietnam)." Fractal and Fractional 7, no. 11 (October 25, 2023): 776. http://dx.doi.org/10.3390/fractalfract7110776.
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The time dynamics of the instrumental seismicity recorded in the area of the Lai Chau reservoir (Vietnam) between 2015 and 2021 were analyzed in this study. The Gutenberg–Richter analysis of the frequency–magnitude distribution has revealed that the seismic catalog is complete for events with magnitudes larger or equal to 0.6. The fractal method of the Allan Factor applied to the series of the occurrence times suggests that the seismic series is characterized by time-clustering behavior with rather large degrees of clustering, as indicated by the value of the fractal exponent α≈0.55. The time-clustering of the time distribution of the earthquakes is also confirmed by a global coefficient of variation value of 1.9 for the interevent times. The application of the correlogram-based periodogram, which is a robust method used to estimate the power spectrum of short series, has revealed three main cycles with a significance level of p<0.01 (of 10 months, 1 year, and 2 years) in the monthly variation of the mean water level of the reservoir, and two main periodicities with a significance level of p<0.01 (at 6 months and 2 years) in the monthly number of earthquakes. By decomposing the monthly earthquake counts into intrinsic mode functions (IMFs) using the empirical decomposition method (EMD), we identified two IMFs characterized by cycles of 10 months and 2 years, significant at the 1% level, and one cycle of 1 year, significant at the 5% level. The cycles identified in these two IMFs are consistent with those detected in the water level, showing that, in a rigorously statistical manner, the seismic process occurring in the Lai Chau area might be triggered by the loading–unloading operational cycles of the reservoir.
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Pavel, Florin, and Robert Vladut. "Assessment of Liquefaction Hazard for Sites in Romania Using Empirical Models." Infrastructures 8, no. 9 (September 5, 2023): 133. http://dx.doi.org/10.3390/infrastructures8090133.
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This paper is focused on the evaluation of the liquefaction hazard for different sites in Romania. To this aim, a database of 139 ground motions recorded during Vrancea intermediate-depth earthquakes having moment magnitudes MW ≥ 6.0 is employed for the evaluation of the equivalent number of cycles for this seismic source. Several functional forms for the empirical evaluation of the equivalent number of cycles considering various seismological or engineering parameters are tested and evaluated. The regression analysis shows smaller uncertainties for the empirical models based on ground motion engineering parameters. Considering the lack of information in terms of engineering parameters, a simpler empirical model which accounts for the earthquake magnitude, source–site distance and soil conditions is selected for the liquefaction hazard analysis. Based on the proposed empirical model, specific magnitude scaling factors for Vrancea intermediate-depth earthquakes are proposed for the first time as well. The liquefaction hazard analysis is performed for sites whose seismic hazard is generated by either the Vrancea intermediate-depth seismic source or by local shallow crustal seismic sources. In the case of some of the selected sites, liquefaction phenomena were observed during past large-magnitude earthquakes. Unlike previous studies dealing with liquefaction analyses for sites in Romania, in this research, the hazard assessment is performed for various ground motion levels evaluated based on probabilistic seismic hazard assessment. Liquefaction hazard curves are constructed for each analyzed site. The results of the liquefaction hazard analysis show that this phenomenon is more likely to occur in the areas exposed to Vrancea intermediate-depth earthquakes, compared to the areas affected by local shallow earthquakes. In the case of the analyzed soil profiles from Bucharest, Craiova and Ianca, the minimum liquefaction safety factors less than one even for seismic hazard levels having mean return periods of 100 years and less.
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Negulescu, Caterina, Kushan K. Wijesundara, and Evelyne Foerster. "Seismic Damage Assessment of Regular Gravity Design Buildings." Key Engineering Materials 569-570 (July 2013): 294–301. http://dx.doi.org/10.4028/www.scientific.net/kem.569-570.294.
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During the past earthquakes, different low ductile failure modes are observed in the gravity design structures and thus, the most of existing damage indices may fail to assess the damage of gravity design structures accurately in referring to the two main performance levels: immediate occupancy and ultimate limit state. Therefore, this study investigates the possible damage indices for the damage assessment of gravity design frames. For this purpose, among the existing damage indices in the literature, this study considers the inter-story drift and the natural period based damage indices. In addition, two new damage indices based on the wavelet based energy and the dominant inelastic period of a building are also considered in this study. Furthermore, the damage assessment results from the four damage indices for three gravity design buildings are compared and discussed. From the comparison, linear correlations between the inter-storey drift based damage index and the wavelet energy based index, and dominant inelastic period based damage index are observed. Finally, this study concludes based on the observations that no significant effects of number of inelastic cycles to the damage assessment results for low ductile structures. However, this study also highlights the effects of number of inelastic cycles to the damage for medium and high ductile structures.
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van Andel, Tjeerd H., Eberhard Zangger, and Constantine Perissoratis. "Quaternary Transgressive/Regressive Cycles in the Gulf of Argos, Greece." Quaternary Research 34, no. 3 (November 1990): 317–29. http://dx.doi.org/10.1016/0033-5894(90)90044-l.
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AbstractBorings in the Argive Plain reveal cycles of marine incursions, each ending with a Mediterranean soil profile and followed by a prograded fluvial and coastal wedge. The sediment prism of the Gulf of Argos shelf, visible in high-resolution seismic reflection profiles, also consists of transgressive and regressive depositional sequences identified by onlap, downlap, and truncation of deposits. At least four major reflectors, recognizable by their high acoustic impedance and erosional features, can be correlated across the shelf. The sediments between each pair of reflectors represent the seaward part of a set of transgressive and regressive marine deposits. They can be matched to the stratigraphic sequence on land where each marine unit is topped by a soil. Corrected for subsidence, the terminations of the onlapping and downlapping units define a local sea-level history; its time scale can be derived from a comparison with the eustatic sea-level history deduced from ocean cores. Thus, marine seismic reflection data can be used for the correlation of Quaternary oceanic and terrestrial chronologies.
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Abdullah, Wrya, Seyed Sasan Khedmatgozar Dolati, and Arjun Basnet. "Inelastic Cyclic Tests of Grade 80 (550 MPa) Bars with Mechanical Splices." Journal of Studies in Civil Engineering 1, no. 1 (June 17, 2024): 1–14. http://dx.doi.org/10.53898/jsce2024111.
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This study addresses low-cycle fatigue performance of high-strength steel reinforcement bars (HSRB) when used with mechanical couplers due to the growing demand for higher-strength steel reinforcement bars in both seismic and non-seismic applications, driven by the need to reduce bar congestion, lower material quantities, and consider economic and environmental factors. Low-cycle fatigue involves material failure owing to a finite number of load or deformation cycles, generally occurring under substantial strain rates that surpasses the yielding limit. The experimental program assesses the fatigue behavior of HSRB produced using microalloying, quenching, and tempering techniques, coupled with mechanical couplers (eleven different types) from five companies in the United Stated of America. The study highlights significant differences in fatigue endurance based on the type and make of couplers and suggests potential improvements in manufacturing processes to enhance fatigue resistance. It is found that the mechanical couplers sustain a loading protocol of (-1% to 3%) when there is a clear distance of 2 times the diameter of the bar between the coupler and the gripping machine from top to bottom. The coupled bars sustained a minimum of 6 half cycles and a maximum of 38 half cycles.
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Kim, Ki-Beom, and Heon-Young Chang. "Relations between global seismic parameters and activity cycles of the Sun." New Astronomy 92 (April 2022): 101720. http://dx.doi.org/10.1016/j.newast.2021.101720.
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McGuire, J. J. "Seismic Cycles and Earthquake Predictability on East Pacific Rise Transform Faults." Bulletin of the Seismological Society of America 98, no. 3 (June 1, 2008): 1067–84. http://dx.doi.org/10.1785/0120070154.
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Niu, Lihua, Shansuo Zheng, Hao Zheng, Yan Zhou, and Pei Pei. "Seismic behavior of confined masonry walls subjected to freeze-thaw cycles." Construction and Building Materials 186 (October 2018): 131–44. http://dx.doi.org/10.1016/j.conbuildmat.2018.07.104.
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Hyodo, Mamoru, and Takane Hori. "Modeling of Nankai earthquake cycles: Influence of 3D geometry of the Philippine Sea plate on seismic cycles." JAMSTEC Report of Research and Development 11 (2011): 1–15. http://dx.doi.org/10.5918/jamstecr.11.1.
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PAZ, J. D. S., and D. F. ROSSETTI. "Linking lacustrine cycles with syn-sedimentary tectonic episodes: an example from the Codó Formation (late Aptian), northeastern Brazil." Geological Magazine 142, no. 3 (May 2005): 269–85. http://dx.doi.org/10.1017/s0016756805000488.
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The Codó Formation exposed in the eastern Grajaú Basin, northeastern Brazil, consists mostly of black shales, limestones and evaporites arranged into several shallowing-upward cycles formed by progradation of lake deposits. Three ranks of cycles are distinguished. The lower-rank cycles correspond to millimetric interbeddings of: bituminous black shales with evaporites, calcimudstones or peloidal wackestone–packstone; grey/green shale with calcimudstone, peloidal wackestone–packstone or ostracodal wackestone/grainstone; and ostracodal wackestone/grainstone and/or calcimudstones with cryptomicrobial mats and ooidal/pisoidal packstones. The intermediate-rank cycles average 1.7 m in thickness and are formed by complete and incomplete cycles. Complete cycles show a transition from central to intermediate and then to marginal facies associations and include two types: C1 cycle with central lake deposits consisting of evaporites and black shales; and C2 cycle with central lake deposits formed by grey/green shale. Complete cycles were produced by the upward gradation from central to marginal environments of the lake or saline pan–sabkha system. Incomplete cycles are those where at least one facies association is lacking, having been formed by successions either with central and intermediate facies associations (I1) or intermediate and marginal facies associations (I2). The higher-rank cycles are, on average, 5.2 m thick and consist of four depositional units that display shallowing-upward successions formed by complete and incomplete intermediate-rank cycles that vary their distribution upward in the section, and are bounded by sharp surfaces. While the lower-rank cycles display characteristics that reveal their seasonal signature, detailed sedimentological characterization and understanding of stratal stacking patterns related to the intermediate and higher-rank cycles support a genesis linked to syn-sedimentary tectonic activity. This is particularly suggested by the high facies variability, limited lateral extension, and frequent and random thickness changes of the intermediate-rank cycles. Additionally, the four higher-rank cycles recognized in the Codó Formation match with stratigraphic zones having different styles of soft-sediment deformation structures attributed to seismic activities. Therefore, the several episodes of lake shallowing recorded in the Codó Formation are linked to seismic pulses that alternated with sediment deposition. This process would have created significant changes in the lake water level and resulted in sharply bounded successions with upward gradation from deeper to relatively shallower facies associations.
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Maia, Renata Moreira da Costa, Antonio Tadeu dos Reis, Eliane da Costa Alves, Cleverson Guizan Silva, Josefa Varela Guerra, Christian Gorini, Adalberto Silva, and Rodrigo Arantes-Oliveira. "Architecture and stratigraphic framework of shelf sedimentary systems off Rio de Janeiro state, Northern Santos Basin-Brazil." Brazilian Journal of Oceanography 58, spe1 (2010): 15–29. http://dx.doi.org/10.1590/s1679-87592010000500003.
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Seismic analysis of sparker lines of GEOMAR cruises allowed us to address a first stratigraphic scenario for the shallow sedimentary record (~300 msec) of the continental shelf off Rio de Janeiro State, northern Santos basin. Two sets of seismic sequences were identified and interpreted as a succession of depositional sequences induced by repeated glacioeustatic cycles. Depositional sequences composing Set I (SqA-SqC) are dominantly sigmoidal, reflecting periods of increasing accommodation space that favoured the preservation of both aggradational and progradational units; sequences of Set II (Sq1-Sq5) are essentially seaward-thickening stacks of forced-regression wedges, implying periods of declining accommodation space. Comparison between seismic lines and chronostratigraphic data allowed the mapped sequences to be placed within the Plio-Quaternary. Correlations also suggest that most of Set I (SqA and lower portion of SqB) was deposited during the Pliocene (undifferentiated Pliocene), while the upper portion of sequence SqC and sequences of Set II (Sq1-Sq5) have been placed within the Quaternary. Correlation of chronostratigraphic data with δ18O isotopic "sea level curves" also supports the hypothesis that sequences Sq1-Sq4 are fourth-order forced-regression sequences that record 100-120 kyr glacioeustatic cycles for the last 440-500 kyr, while sedimentary units labeled Sq5 would represent the transgressive and highstand deposition during the Holocene.
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Geary, Andrew. "Seismic Soundoff: Breaking down the life cycle of a well." Leading Edge 41, no. 4 (April 2022): 284. http://dx.doi.org/10.1190/tle41040284.1.
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In this episode, Sue Carr and Patrick Meroney discuss the importance of a shared definition of a well, the most important well component for geophysicists, the five life cycles of a well, and why well logs are key to successful drilling. Hear the full episode at https://seg.org/podcast/post/13689 .
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Li, Fan Xiu. "Five-Element Connection Number Method for Seismic Damage Evaluation on RC Structure." Advanced Materials Research 255-260 (May 2011): 2461–65. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.2461.
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In view of the problem that seismic damage evaluation for reinforced concrete structure are difficult to quantify, a new model for seismic damage evaluation was established by five-element connection number based on set pair analysis in the paper, which took internal damage index, maximum inter-storey drift, number of inelastic cycles and energy-concentrated quotient as evaluation factors. All indexes can be summarized into five-element connection number. Four different types of structure are analyzed on the model with more satisfactory results. Compared with the matter-element analysis evaluation method, this model is perfect, the evaluating result is more reasonable and its resolving power is higher. By this practical example, the model proved to be effective in seismic damage evaluation on reinforced concrete structure.
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Greco, Rita, Giuseppe Carlo Marano, and Alessandra Fiore. "Damage-Based Inelastic Seismic Spectra." International Journal of Structural Stability and Dynamics 17, no. 10 (November 20, 2017): 1750115. http://dx.doi.org/10.1142/s0219455417501152.
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Current inelastic seismic spectra suffer from a conceptual limitation: they are significant only on the maximum demand of ductility and they do not include any influence of the number of response cycles, yield excursions, stiffness and strength degradation and damage potential to structures. This paper presents a stochastic approach for obtaining damage-based inelastic seismic spectra. In order to consider the cumulative damage phenomenon in structural systems under strong ground motions, the authors adopt the Park and Ang damage model that includes the displacement ductility and the hysteretic energy. The novelty is that the peak theory of random processes is adopted to achieve damage-based seismic spectra. This approach has some advantages compared with the standard statistical approaches based on a large number of recorded accelerograms. First, it drastically reduces the computational effort, while allowing us to typify the seismic motion by some parameters such as the frequency content, peak acceleration, energy content and strong motion duration, i.e. all the parameters that affect the structural response under seismic actions. Besides, it allows to obtain the following stochastic inelastic seismic response spectra: damage-based (i) displacement and acceleration inelastic spectra, (ii) response modification factor spectra, (iii) yield strength demand spectra, and (iv) damage-based inelastic displacement ratio spectra.
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Jain, Kiran, Niket Jain, Sushanta C. Tripathy, and Mausumi Dikpati. "What Seismic Minimum Reveals about Solar Magnetism below the Surface." Astrophysical Journal Letters 924, no. 1 (January 1, 2022): L20. http://dx.doi.org/10.3847/2041-8213/ac3de9.
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Abstract The Sun’s magnetic field varies on multiple timescales. Observations show that the minimum between cycles 24 and 25 was the second consecutive minimum that was deeper and wider than several earlier minima. Since the active regions observed at the Sun’s surface are manifestations of the magnetic field generated in the interior, it is crucial to investigate/understand the dynamics below the surface. In this context, we report by probing the solar interior with helioseismic techniques applied to long-term oscillations data from the Global Oscillation Network Group, that the seismic minima in deeper layers have been occurring about a year earlier than that at the surface for the last two consecutive solar cycles. Our findings also demonstrate a decrease in strong magnetic fields at the base of the convection zone, the primary driver of the surface magnetic activity. We conclude that the magnetic fields located in the core and near-surface shear layers, in addition to the tachocline fields, play an important role in modifying the oscillation frequencies. This further strengthens the existence of a relic magnetic field in the Sun’s core.
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Apak, S. N., and H. T. Moors. "A SEQUENCE STRATIGRAPHIC DEPOSITIONAL MODEL OF NEOPROTEROZOIC STRATA, YOWALGA AREA, OFFICER BASIN,WESTERN AUSTRALIA." APPEA Journal 40, no. 1 (2000): 15. http://dx.doi.org/10.1071/aj99001.
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Additional data and further studies have now improved geological, geophysical, and geochemical understanding of the Neoproterozoic strata of the Officer Basin. New sequence stratigraphic analysis of continuously cored drillholes (particularly Empress–1/1A), extended throughout the area with wireline log and seismic correlations, provide enhanced recognition of depositional fades and thus basin architecture. Four major flooding events and fifteen sedimentary successions, interpreted as parasequence sets by regional correlation, are recognised across the Yowalga area. These parasequence sets are traceable using seismic data, with flooding events identified on cores and logs producing regional or local reflectors with good amplitude and continuity.Sedimen tary cycles are dominantly mixed carbonates- siliciclastics with primarily progradational stacking patterns. These imply transgressive and regressive cycles in a basin with low bathymetric relief. Depositional settings range from supratidal to just below storm wave base.This interpretation improves the prediction of potential petroleum systems. An architectural model for each formation allows prediction of depositional trends including potential reservoir, source rock and seal in the Yowalga area.
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Donaire-Ávila, Jesús, and David Galé-Lamuela. "Energy Capacity of Waffle-Flat-Plate Structures with Hysteretic Dampers Subjected to Bidirectional Seismic Loadings." Applied Sciences 10, no. 9 (April 30, 2020): 3133. http://dx.doi.org/10.3390/app10093133.
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This study investigates the capacity, in terms of energy, of waffle-flat-plate (WFP) structures with hysteretic dampers subjected to biaxial seismic actions. A numerical model was developed and calibrated with the experimental results obtained from shake-table testing carried out on a WFP specimen subjected to biaxial seismic loads. Then the WFP system was retrofitted with hysteretic dampers—slit-plate dampers (SPDs)—and the numerical model was subjected to different sets of ordinary ground motion records to attain different seismic performance levels (SPLs). Each set of records was applied in a sequence of scaled seismic simulations until the SPL of near collapse was achieved. The capacity in terms of input energy and dissipated energy are presented for the different SPLs, taking into account the differences observed under unidirectional and bidirectional seismic loadings. Furthermore, the level of damage (i.e., accumulated plastic deformations), the level of ductility and the relationship between them—expressed as equivalent number of cycles—are also shown for both the WFP system and the hysteretic dampers. The seismic capacity of the WFP system is found to be significantly enhanced by the inclusion of hysteretic dampers.