•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.
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
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.
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.
•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.
Seismic assessment and design of structures nominally require large numbers of analyses with high-fidelity models—e.g., to obtain fragility curves–especially for regional scale tasks. In this study, ...a deep learning-enhanced multi-fidelity modeling approach is devised that can dramatically increase the computational efficiency of such analyses. This approach uses high- and low-fidelity numerical models for generating small and large sample responses first. Then, a deep learning-based projection model is trained with the limited high-fidelity data to learn the correlations within multi-fidelity results with the objective of having a trained model that can predict high-fidelity results from low-fidelity simulations. For validating this approach, a reinforced concrete frame and a high-rise shear-wall structure are used as validation and application examples, and the impacts of various key factors in training and model generation are examined. The results indicate that the proposed approach can effectively accelerate seismic analyses without compromising accuracy.
The process of soil response influencing motion of the structure and vice-versa is termed as soil-structure interaction (SSI). SSI has been traditionally considered to be beneficial to seismic ...response of a structure. It has been suggested that ignoring SSI in design practice leads to a conservative design. It is evident from the design codes which either allow a reduction of the overall seismic coefficient on account of SSI or suggest it to be ignored altogether. However observations from some of the past seismic events such as 1989 Loma Prieta earthquake and 1995 Kobe Earthquake show evidences of detrimental nature of SSI in certain circumstances. Recent studies have also been able to justify such possibilities. As a consequence of this dissent among the research fraternity, there is a lack of adequately formulated design guidelines. Though advances have been made in developing methods to solve an SSI problem, incorporating SSI in design practice has been a rarity. The present paper attempts to summarize various approaches to include SSI in analysis of structures and guidelines outlined in prominent seismic codes. The significance of such a study lies in the need for selection of appropriate approach. A review of contemporary research in field of SSI is also presented at the end.
•Significance of soil-structure interaction (SSI) in seismic design is established.•Various approaches to solve an SSI problem are explained.•SSI provisions in prominent seismic codes are discussed.•Contemporary research in field of SSI is reviewed.
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.
