scholarly journals Comparative assessment of finite element macro-modelling approaches for seismic analysis of non-engineered masonry constructions

2021 ◽  
Author(s):  
Nagavinothini Ravichandran ◽  
Daniele Losanno ◽  
Fulvio Parisi
Keyword(s):  
Finite Element ◽  
Seismic Vulnerability ◽  
Seismic Analysis ◽  
Regional Scale ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Simplified Model ◽  
Experimental Comparison ◽  
Response Analysis ◽  
Masonry Buildings

AbstractAll around the world, non-engineered masonry constructions (NECs) typically have high vulnerability to seismic ground motion, resulting in heavy damage and severe casualties after earthquakes. Even though a number of computational strategies have been developed for seismic analysis of unreinforced masonry structures, a few studies have focussed on NECs located in developing countries. In this paper, different modelling options for finite element analysis of non-engineered masonry buildings are investigated. The goal of the study was to identify the modelling option with the best trade-off between computational burden and accuracy of results, in view of seismic risk assessment of NECs at regional scale. Based on the experimental behaviour of a single-storey structure representative of Indian non-engineered masonry buildings, the output of seismic response analysis of refined 3D models in ANSYS was compared to that of a simplified model based on 2D, nonlinear, layered shell elements in SAP2000. The numerical-experimental comparison was carried out under incremental static lateral loading, whereas nonlinear time history analysis was performed to investigate the dynamic performance of the case-study structure. Analysis results show that the simplified model can be a computationally efficient modelling option for both nonlinear static and dynamic analyses, particularly in case of force-based approaches for design and assessment of base isolation systems aimed at the large-scale seismic vulnerability mitigation of NECs.

scholarly journals A Probabilistic Capacity Model and Seismic Vulnerability Analysis of Wall Pier Bridges

2020 ◽  
Vol 10 (3) ◽  
pp. 926 ◽  
Author(s):  
Libo Chen ◽  
Yi Tu ◽  
Leqia He
Keyword(s):  
Finite Element ◽  
Seismic Vulnerability ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Finite Element Models ◽  
Unknown Parameters ◽  
Element Analysis ◽  
Performance Point ◽  
Capacity Model ◽  
Damage States

This study aims to establish a probabilistic capacity model of a wall pier under various damage states, and the seismic vulnerability of a typical wall pier bridge is studied. The finite element analysis of the wall pier is carried out by using the layered shell element, and its accuracy is verified through the comparison with the experimental results. A series of wall pier samples are generated based on the survey data, and the corresponding finite element models are established. The hysteresis analysis is implemented to obtain the displacement drift ratio of each seismic performance point. A candidate capacity model with various factors is proposed, and the unknown parameters are estimated and filtered by the Bayesian method. One hundred and twenty bridge samples of a benchmark bridge are generated by considering the uncertainty of parameters, and the finite element models are established. The bridge samples and ground motions were matched by one-to-one correspondence for the nonlinear time history analysis, and seismic vulnerability models of bridge components and system are obtained. The results showed that the in-plane capacity of wall piers is mainly affected by axial compression ratio, shear span ratio, and vertical reinforcement ratio. The wall pier shows excellent behavior in the earthquakes. The capacity models of wall piers can be used for evaluating the damage states of wall piers, and obtaining the seismic vulnerability model of wall piers bridges to be used for future seismic risk assessment and retrofit prioritization.

Investigation on Effect of Analysis Variables on Structural Integrity of the Nuclear Piping Under Beyond Design Basis Earthquake

2017 ◽  
Author(s):  
Jong-Sung Kim ◽  
Suk-Hyun Lee ◽  
Hyeong Do Kweon
Keyword(s):  
Finite Element ◽  
Structural Integrity ◽  
Seismic Analysis ◽  
Time History ◽  
Time History Analysis ◽  
Design Basis ◽  
History Analysis ◽  
Study Results ◽  
Transition Length ◽  
Dynamic Time

In this study, effect of analysis variables on structural integrity of nuclear piping under beyond design basis earthquake was investigated via performing dynamic time history seismic analysis. A finite element model of the piping system such as shut-down cooling line was developed combining solid and beam elements. Dynamic time history analysis was performed via finite element elastic plastic stress analysis. Validity of the dynamic time history analysis procedure was verified via comparing with the previous study results. Finally, the effect of analysis variables such as finite element characteristics, transition length between elbow and straight line, fluid effect, etc. was investigated via performing parametric dynamic time history seismic analysis. As a result, it was found that use of the 1st incompatible element is recommended, the transition length is the same as curvature of the elbow, and fluid has to be considered.

Efficient Intensity Measures for Probabilistic Seismic Response Analysis of Anchored Above-Ground Liquid Steel Storage Tanks

2016 ◽  
Author(s):  
Hoang Nam Phan ◽  
Fabrizio Paolacci
Keyword(s):  
Ground Motion ◽  
Earthquake Engineering ◽  
Nuclear Power ◽  
Power Plants ◽  
Seismic Analysis ◽  
Time History ◽  
Response Analysis ◽  
Storage Tanks ◽  
Intensity Measures ◽  
Study Results

Liquid storage tanks are vital lifeline structures and have been widely used in industries and nuclear power plants. In performance-based earthquake engineering, the assessment of probabilistic seismic risk of structural components at a site is significantly affected by the choice of ground motion intensity measures (IMs). However, at present there is no specific widely accepted procedure to evaluate the efficiency of IMs used in assessing the seismic performance of steel storage tanks. The study presented herein concerns the probabilistic seismic analysis of anchored above-ground steel storage tanks subjected to several sets of ground motion records. The engineering demand parameters for the analysis are the compressive meridional stress in the tank wall and the sloshing wave height of the liquid free surface. The efficiency and sufficiency of each alternative IM are quantified by results of time history analyses for the structural response and a proper regression analysis. According to the comparative study results, this paper proposes the most efficient and sufficient IMs with respect to the above demand parameters for a portfolio of anchored steel storage tanks.

scholarly journals Seismic vulnerability of traditional masonry building a case study of Byasi, Bhaktapur

2017 ◽  
Vol 4 ◽  
pp. 24-30
Author(s):  
Shyam Sundar Basukala ◽  
Prem Nath Maskey
Keyword(s):  
Seismic Vulnerability ◽  
Linear Time ◽  
Fragility Curves ◽  
Time History ◽  
Masonry Building ◽  
Masonry Buildings ◽  
Masonry Structures ◽  
Rapid Visual Screening ◽  
Visual Screening

Historic buildings of Nepal are mainly constructed from masonry structure. Since masonry structures are weak in tension which leads to the failure of structure. So, to avoid possible damage in environment lives and property it is urgent to conduct vulnerability assessments. Seismic vulnerability of historic masonry buildings constructed in Bhaktapur at Byasi area is carried out for the case study. Five load bearing masonry buildings were selected out of 147 buildings considering opening percentage, storey and type of floor for modeling in SAP 2000 V10 Various methods of rapid visual screening (FEMA 154, EMS 98) are used to determine the vulnerability of the selected building. The Selected Building response is carried out by linear time history analysis. The seismic vulnerability of masonry structures is determined in terms of fragility curves which represent the probability of failure or damage due to various levels of strong ground motions for different damage state slight, moderate, extensive and collapse. From the result of Rapid Visual Screening (RVS) and Fragility curves of the buildings it is found that whole, buildings are found vulnerable from future earthquake.

The Longitudinal Seismic Analysis of Single-Story and Single-Span Gabled Frame Structures

2015 ◽  
Vol 744-746 ◽  
pp. 335-339
Author(s):  
Hong Dong Ran ◽  
Le Chen ◽  
Yun Mei Ma
Keyword(s):  
Seismic Analysis ◽  
Time History ◽  
Steel Structure ◽  
National Standard ◽  
Nonlinear Time History Analysis ◽  
Frame Structures ◽  
Seismic Action ◽  
Light Weight ◽  
Standard Design ◽  
Nonlinear Time History

Four single-story single-span Gabled Frame Structures (GFSs) which included in China national Standard Design Drawing of Light-weight Steel Structure with Gabled Frame (02SG518-1) were studied and their longitudinal seismic performances were evaluated through extensive nonlinear time-history analysis using eight ground motions representing the Frequent Earthquake, DBE and the MCE hazard levels, the load-bearing performances, deformation capacities and the curves of displacement were studied. The analysis results showed that the longitudinal seismic action of all GFSs considered in this study is very little, the displacement at the top of the column can satisfy the demands of the Technical Specificationfor Steel Structure of Light-weight Building with Gabled Frames even in MCE. The GFSs designed followed the Specificaiton have the excellent longitudinal seismic performance.

scholarly journals Nonlinear Seismic Behavior of Different Boundary Conditions of Transmission Line Systems under Earthquake Loading

2016 ◽  
Vol 2016 ◽  
pp. 1-9
Author(s):  
Li Tian ◽  
Xia Gai
Keyword(s):  
Boundary Conditions ◽  
Transmission Line ◽  
Transmission Lines ◽  
Seismic Analysis ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Earthquake Loading ◽  
Transmission Tower ◽  
Line System ◽  
Different Boundary Conditions

Nonlinear seismic behaviors of different boundary conditions of transmission line system under earthquake loading are investigated in this paper. The transmission lines are modeled by cable element accounting for the nonlinearity of the cable. For the suspension type, three towers and two span lines with spring model (Model 1) and three towers and four span lines’ model (Model 2) are established, respectively. For the tension type, three towers and two span lines’ model (Model 3) and three towers and four span lines’ model (Model 4) are created, respectively. The frequencies of the transmission towers and transmission lines of the suspension type and tension type are calculated, respectively. The responses of the suspension type and tension type are investigated using nonlinear time history analysis method, respectively. The results show that the responses of the transmission tower and transmission line of the two models of the suspension type are slightly different. However, the responses of transmission tower and transmission line of the two models of the tension type are significantly different. Therefore, in order to obtain accurate results, a reasonable model should be considered. The results could provide a reference for the seismic analysis of the transmission tower-line system.

Seismic Response Analysis of Twin-Tower Building with Enlarged Base

2014 ◽  
Vol 912-914 ◽  
pp. 1534-1537
Author(s):  
Shao Bo Zhang ◽  
Ke Lun Wei ◽  
Bi Jian Xiao
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Boundary Conditions ◽  
Seismic Response ◽  
Time History ◽  
Response Analysis ◽  
Rigid Boundary ◽  
Finite Element Software ◽  
Elastic Boundary ◽  
Elastic Boundary Conditions

This paper adopts large finite element software ANSYS to establish finite element model of twin-tower building with enlarged base, uses dynamic time history analysis method for seismic response calculation, compare and analyze the calculation results of twin-tower building with enlarged base under elastic boundary conditions and rigid boundary conditions. The results showe that dynamic response for model under elastic boundary conditions is larger than dynamic response for model under rigid boundary conditions, and elastic boundary conditions is more close to the actual situation.

Study on Methods for HCLPF Value of Nonlinear Supports System of Steam Generator

2018 ◽  
Author(s):  
Feng-chun Cai ◽  
Xian-hui Ye ◽  
Qian Huang ◽  
Wenzheng Zhang
Keyword(s):  
Steam Generator ◽  
Nonlinear Model ◽  
Seismic Analysis ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Cost Calculation ◽  
Seismic Capacity ◽  
Ground Acceleration ◽  
Reactor Building ◽  
Nonlinear Time History

High confidence of low probability of failure (HCLPF) values of equipment, representing the seismic capacities of the equipment, are the fundamental ingredient in seismic probability safety assessment (SPSA) and seismic margin analyses (SMA). In this paper, two methods for calculating the HCLPF values of equipment were investigated, fragility analysis, and conservative deterministic failure margin (CDFM). These methods are linear methods. Based on these methods, HCLPF value of equipment can be computed conveniently by scaling the results of the existing seismic analysis. For a nonlinear systems, the HCLPF values based on these linear scaling methods are unrealistic. For a complicated nonlinear equipment or structure, a detail nonlinear model was used to derive the seismic capacity. The results by this method are realistic, but cost calculation time. In this paper, a nonlinear model of reactor coolant system coupled reactor building was built. This model includes the steam generator and considers the nonlinear factors of steam generator such as gap in the supports, plasticity of hot leg and cold leg. Forced motion was applied to the base of reactor building. And seismic response of the steam generator was calculated iteratively by scaling the ground motion level step by step. Based on these calculations, a curve of load on the supports VS peak ground acceleration (PGA) can be obtained. Then based on these curves and allowable load of supports of steam generator, which derived from stress analysis on support of steam generator, seismic capacity of the supports of steam generator was determined. Then the HCLPF Value of the supports of steam generator was obtained by this nonlinear time history analysis and was compared with the results based on the CDFM. The two results were different. Therefore, the HCLPF seismic capacity of equipment with nonlinearity, such as gap nonlinearity, should be calculated by nonlinear time history method.

scholarly journals Classification of Earthquake-Induced Damage forR/CSlab Column Frames Using Multiclass SVM and Its Combination with MLP Neural Network

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Ali Kia ◽  
Serhan Sensoy
Keyword(s):  
Neural Network ◽  
Seismic Vulnerability ◽  
Gaussian Function ◽  
Damage Index ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Support Vector ◽  
Damage Classification ◽  
Ground Acceleration

Nonlinear time history analysis (NTHA) is an important engineering method in order to evaluate the seismic vulnerability of buildings under earthquake loads. However, it is time consuming and requires complex calculations and a high memory machine. In this study, two networks were used for damage classification: multiclass support vector machine (M-SVM) and combination of multilayer perceptron neural network with M-SVM (MM-SVM). In order to collect data, three frames ofR/Cslab column frame buildings with wide beams in slab were considered. For NTHA, twenty different ground motion records were selected and scaled to ten different levels of peak ground acceleration (PGA). Thus, 600 obtained data from the numerical simulations were applied to M-SVM and MM-SVM in order to predict the global damage classification of samples based on park and Ang damage index. Amongst the four different kernel tricks, the Gaussian function was determined as an efficient kernel trick using the maximum total accuracy method of test data. By comparing the obtained results from M-SVM and MM-SVM, the total classification accuracy of MM-SVM is more than M-SVM and it is accurate and reliable for global damage classification ofR/Cslab column frames. Furthermore, the proposed combined model is able to classify the classes with low members.

Elastoplastic Seismic Response Analysis of Masonry Buildings with Variable Wall Thickness along Height

2010 ◽  
Vol 452-453 ◽  
pp. 101-104
Author(s):  
Bai Tao Sun ◽  
Hong Fu Chen
Keyword(s):  
Failure Mechanism ◽  
Wall Thickness ◽  
Time History ◽  
Response Analysis ◽  
Masonry Buildings ◽  
The Finite Element Method ◽  
Variable Wall Thickness ◽  
Variable Wall ◽  
Input Motion ◽  
Lateral Stiffness Ratio

The multistory masonry buildings with variable wall thickness along the height have suffered different degrees of damage subjected to the Wenchuan earthquake. In order to study the failure mechanism of such masonry structure under the earthquake, three types of five-story structure of computational model are firstly introduced in this paper, including (1) the wall thickness of five stories is 240mm; (2) the wall thickness of the first floor is 370mm, and that of the upper four stories is 240mm; (3) the wall thickness of the first and second story is 370mm, and that of the other stories is 240mm. Then, the elastoplastic time-history dynamic analysis is carried on with the story shear model by the finite element method, and the ground motion of El Centro waves are adopted as earthquake input motion. The analysis results show that variation of wall thickness along height can easily cause stiffness mutation of the upper and lower floor, lead to local floor deformation concentration and soft floors, and the change of failure mechanism of the structure. Finally, it is suggested that some appropriate seismic resistance measures should be taken to meet the lateral stiffness ratio of the upper and lower floor in the later design of this structure, or this kind of structure should be avoided using as far as possible.

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