Many high concrete-faced rockfill dams (CFRDs) are located in areas with high earthquake intensity where the ground motions are characterized by randomness; consequently, it is significant to study ...the seismic responses and evaluate the seismic performance using dynamic time-history analysis by a stochastic vibration method based on failure probability theory. In this paper, a recently developed generalized probability density evolution method (GPDEM) coupled with a spectral representation-random function method is verified to be suitable for strongly nonlinear structures in high CFRDs during earthquakes by comparing the accuracy and efficiency of the GPDEM with those of the Monte Carlo method (MCM). The GPDEM combined with the currently deterministic dam finite element time-history response analysis using a series of simple and common methods, is adopted to analyze the stochastic seismic responses, dynamic probability evaluation and failure probability of high CFRDs subjected to stochastic earthquake excitation. The statistical and probabilistic information of the typical physical quantities are compared between the GPDEM and MCM after a series of deterministic dynamic calculations, and the dynamic nonlinear behavior of rockfills and the random characteristics of ground motions are presented. The strong correspondence between the results obtained using the traditional stochastic probability MCM analysis and the GPDEM analysis demonstrates the accuracy and effectiveness of the newly proposed method despite its significantly lower computational burden. Finally, the failure probabilities of a high CFRD with different failure grades based on three universal evaluation indices are determined by constructing a virtual GPDEM process. The results demonstrate that the GPDEM shows promise as an approach that can reliably analyze strongly nonlinear structures, such as earth-rockfill dams and other geotechnical engineering structures.
•Seismic time-history response of high CFRDs was analyzed using some simple models and methods.•The precision and efficiency of GPDEM were verified by comparing with MCM.•The statistical and probability information of three typical physical quantities was compared.•The failure probabilities of three universal evaluating indices were obtained based on GPDEM.•The seismic performance of high CFRDs was evaluated from stochastic and probability viewpoint.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract For large-caliber mid-pressure ducts and its supporting rack systems, use the combination of shell units, beam units, and contact units to establish a three-dimensional finite element model ...of reality structure characteristics. Analyze the inherent frequency of the system. Based on modal analysis results, the eight-level earthquake response spectrum in Shanghai is used as input, a multi-point response spectrum analysis under OBE seismic conditions is performed on the rack system. According to the ASME AG-1 specification, the stress intensity and deformation stiffness assessment of the branch line-type structure under the combination of OBE operating conditions are evaluated. Results showed that the optimal form of the air tube of the A-B section was to increase the seismic oblique support and the inner wall was reinforced. The modeling and assessment methods in the paper have a certain reference value for large-scale duct resistance design and safety assessment.
With the dramatic growth and complexity of seismic data, manual seismic facies analysis has become a significant challenge. Machine learning and deep learning (DL) models have been widely adopted to ...assist geophysical interpretations in recent years. Although acceptable results can be obtained, the uninterpretable nature of DL (which also has a nickname "alchemy") does not improve the geological or geophysical understandings on the relationships between the observations and background sciences. This article proposes a noble interpretable DL model based on 3-D (spatial-spectral) attention maps of seismic facies features. Besides regular data-augmentation techniques, the high-resolution spectral analysis technique is employed to generate multispectral seismic inputs. We propose a trainable soft attention mechanism-based deep dilated convolutional neural network (ADDCNN) to improve the automatic seismic facies analysis. Furthermore, the dilated convolution operation in the ADDCNN generates accurate and high-resolution results in an efficient way. With the attention mechanism, not only the facies-segmentation accuracy is improved but also the subtle relations between the geological depositions and the seismic spectral responses are revealed by the spatial-spectral attention maps. Experiments are conducted, where all major metrics, such as classification accuracy, computational efficiency, and optimization performance, are improved while the model complexity is reduced.
Performance-based earthquake engineering aims to quantify performance of facilities using metrics that are of immediate use to both engineers and stakeholders. A rigorous yet practical implementation ...of a performance-based earthquake engineering methodology is developed and demonstrated for an idealized building. The methodology considers seismic hazard, structural response, resulting damage, and repair costs associated with restoring the building to its original condition, using a fully consistent, probabilistic analysis of the associated parts of the problem. The methodology can be generalized to consider other performance measures such as casualties and down time, though these have not been pursued. The proposed procedure is consistent with common building design, construction, and analysis practices such that it can be readily adopted in earthquake engineering practice today.
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DOBA, FGGLJ, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Seismic hazard modeling is a multidisciplinary science that aims to forecast earthquake occurrence and its resultant ground shaking. Such models consist of a probabilistic framework that quantifies ...uncertainty across a complex system; typically, this includes at least two model components developed from Earth science: seismic source and ground motion models. Although there is no scientific prescription for the forecast length, the most common probabilistic seismic hazard analyses consider forecasting windows of 30 to 50 years, which are typically an engineering demand for building code purposes. These types of analyses are the topic of this review paper. Although the core methods and assumptions of seismic hazard modeling have largely remained unchanged for more than 50 years, we review the most recent initiatives, which face the difficult task of meeting both the increasingly sophisticated demands of society and keeping pace with advances in scientific understanding. A need for more accurate and spatially precise hazard forecasting must be balanced with increased quantification of uncertainty and new challenges such as moving from time‐independent hazard to forecasts that are time dependent and specific to the time period of interest. Meeting these challenges requires the development of science‐driven models, which integrate all information available, the adoption of proper mathematical frameworks to quantify the different types of uncertainties in the hazard model, and the development of a proper testing phase of the model to quantify its consistency and skill. We review the state of the art of the National Seismic Hazard Modeling and how the most innovative approaches try to address future challenges.
Plain Language Summary
In this review paper we describe the state of the art in modeling earthquake hazard at the national scale. National hazard models take our understanding of fundamental earthquake processes and develop models of earthquake shaking relevant to the decades to come. The shaking estimates from the models provide important inputs into societal decision making across a wide range of uses including such things as building design requirements or for guiding insurance policy. Here were introduce national models from 10 regions around the world, including multinational models that aim to make results comparable from nation to nation. We describe key challenges and assumptions in making the models and provide recommendations about research for improving future generations of national models. An emerging and overriding philosophy is the need to better quantify and make useful the uncertainties in our knowledge of earthquake processes. Future models will better be able to include this uncertainty and will aim to better quantify the ability of the models to provide the outputs society needs. Finally, future models will become increasingly reliant on computer models that simulate how earthquakes interact with each other and cause shaking at the surface of the Earth.
Key Points
National Seismic Hazard Models (NSHMs) are regional models that take our understanding of earthquake occurrence and their consequent shaking intensities and make this information useful for decision makers and society
Key goals in modern probabilistic NSHMs are the improved quantification of uncertainty and research to understand the skill and usefulness of the forecasts
Current PSHA‐based methods used by NSHMs from diverse tectonic settings around the world are reviewed
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
This article proposed a seismic analysis method for rectifier transformer of International Thermonuclear Experimental Reactor (ITER) poloidal field converter based on response spectrum. The seismic ...response of structure under specific seismic excitation is evaluated by using the earthquake spectrum of seismic level one (SL-1) with damping factor of 2% provided by ITER. The results show the maximum deformation and stress are 31.18 mm (control cubicle) and 181.62 MPa (support of oil tank), respectively, which are less than the allowable stress. In addition, the simulation analysis is introduced in detail and the results as the displacements, stresses, and reactive forces are also presented. The seismic analysis method proposed in this article provided a reference for the seismic design of rectifier transformer of ITER polar field converter, and also provides ideas for the seismic design of similar large electrical equipment.
This study investigates the seismic behavior of L-shaped unreinforced concrete-block masonry fence walls. Using a large-scale shaking table, the walls are subjected to uniaxially artificial ground ...motions that gradually increase in intensity, and the out-of-plane response and failure mode are analyzed. The seismic behavior is then simulated by LS-DYNA using a finite element model under identical conditions as the shaking table tests. The validity of the numerical model is evaluated by comparing the linear response and failure mode of the tests with those of the simulations. Practical modeling techniques and calibrated material model parameters that facilitate reliable simulation results are also presented. The numerical model and techniques are useful in determining the geometrical features required for earthquake-resistant fence walls, such as the maximum permissible width and height as well as the appropriate height- and width-to-thickness ratios, depending on wall support conditions.
•Shaking table tests on L-shaped masonry walls are performed.•The detailed micro-modeling methodology is employed for numerical simulation.•Simulation effectively predicts the damage progress of the L-shaped masonry wall.•Calibrated CSCM parameters for mortar joints are proposed.•Useful numerical modeling techniques are introduced.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•New efficient methods are presented to classify failure modes in RC columns.•Machine learning techniques were utilized to predict the failure modes.•The comparison study shows the desired accuracy ...of the proposed model.•The proposed techniques could specify the failure mode without a complex calculation.•The models have many applications in structural engineering.
In this article, new efficient methods are presented to classify failure modes in reinforced concrete columns. For this purpose, machine learning techniques were utilized with consideration of laboratory datasets collected from the literature. Two different approaches, including decision tree and artificial neural network, have been studied to determine the failure mode of the columns. The variables used to estimate the failure mode were compressive strength of the concrete, span-to-depth ratio, axial load ratio, longitudinal reinforcement ratio, volumetric transverse reinforcement ratio, yield stress of longitudinal reinforcement, and yield stress of transverse reinforcement. A comparison study between the two introduced models indicated that the proposed decision tree provides a desirable accuracy and could specify the failure mode, with no need to a complex calculation. The proposed model has many applications in structural engineering such as seismic evaluation, retrofitting, and rehabilitation as a suitable tool for estimating the failure modes in reinforced concrete columns.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•We developed a two-beam model to represent the nonlinear friction in the fuel assembly.•The proposed model can capture the variation of the resonance frequency of the fuel assembly as the seismic ...load increases.•The proposed model can capture the hysteresis behavior of the fuel assembly under cyclic loads.
Seismic events may lead to vibrations of fuel assemblies in the nuclear reactor cores, thus the dynamic analysis of such vibration of fuel assemblies is essential for the safety design of nuclear reactor plant. In this paper, by considering the friction between fuel pins, we proposed a nonlinear mechanical model for both static and dynamic analysis of fuel assemblies for pressurized water reactor (PWR). The proposed model used a two-beam structure with frictional units to mimic friction and possible contacts in the pin bundle during the static and dynamic loading in the air. By using this approach, we could characterize not only the hysteresis loop during the static bending test (the static slingshot experiment), but also the decrease of resonance frequency with increase of seismic load. Further, maximum contact forces during the seismic test are compared with experiment at various impact locations, and the predictions closely match the experimental findings, affirming the scientific validity and accuracy of the proposed model. The proposed model can be further used to analyzing seismic behavior of the entire reactor core structure, providing valuable insights for assessing reactor structural safety and predictive hazard assessments.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
Safety of water tanks is very important as they are very important life living structures. Tanks shall always be functional for the access to drinking purpose as well as for the requirement ...of fire fighting in the area of occurrence of earthquake. The study focus on analysis of RC water tank of circular shape in accordance with IS 1893 (Part-2):2014. The analysis of tank is carried out for zones II, III, IV and V and Rocky or Hard Soil, Medium Stiff Soil and Soft Soil conditions in accordance to Indian standard. Further three different depth of water with constant diameter ratios with tank full, half-filled and tank empty condition are considered for analysis. From the analysis, it is found that tank design is governed in full tank condition. Values of seismic horizontal design coefficient in impulsive mode (Ahi) are less than those for convective mode (Ahc), for full tank condition. This is due to lower values of time period in impulsive mode. For the same soil condition, values of Ahi and Ahc increases for higher seismic zone. The values of highest shear and moment at bottom of container are found to be governing in full tank condition as compared with half-filled and empty tank condition.
