scholarly journals Multidimensional Fragility Analysis for a NEES Frame Structure by Integrating a New Energy Damage Index: Cumulative Plastic Strain

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Qiang Wang ◽  
Ziyan Wu
Keyword(s):  
Plastic Strain ◽  
Fragility Curves ◽  
Limit State ◽  
Damage Index ◽  
Cumulative Effect ◽  
Frame Structure ◽  
Fragility Analysis ◽  
Threshold Values ◽  
Performance Limit ◽  
Cumulative Plastic Strain

Cumulative plastic strain (CPS) damage index is proposed in this study for seismic fragility analysis by integrating the force analogy method into the energy balance equation, and CPS can be defined as the ratio of the demand of plastic dissipation energy to its capacity. The cumulative plastic strain can indicate the structural damage cumulative effect under earthquakes, which makes it especially suitable to be selected as the damage index for the structural component. Threshold values of cumulative plastic strain for different performance limit state (PLS) levels are obtained through the degree of consistency of interstory drift-based fragility curves and CPS-based fragility curves. Regarding the multidimensional fragility evaluation, CPS and the floor acceleration will be selected as the quantification indices for performance limit state of the structural component and nonstructural component, respectively. The probabilistic seismic demand model (PSDM) following multivariate logarithmic normal distribution will be developed, and taking PLS uncertainty and correlation into consideration, multidimensional PLS function is constructed to identify the structural failure domain. A full-scale 2-bay 2-story frame structure for the Network for Earthquake Engineering Simulation (NEES) project is employed as the case study structure to demonstrate the proposed theory. Nonlinear dynamic time-history analysis is carried out for the structure to obtain its maximum responses under earthquakes. Consequently, the multidimensional fragility curves can be derived on the basis of CPS. Besides, the influence of PLS threshold value, engineering demand parameter (EDP) correlation, and PLS correlation on the multidimensional fragility is investigated. Results show that (1) CPS damage index can fully consider the cumulative effect of damage under earthquakes, which makes up for the deficiency of the interstory drift damage index in this aspect, (2) the multidimensional fragility framework can deal with the PLS correlation and EDP correlation simultaneously, which will generate a more precise seismic damage assessment result, and (3) multidimensional fragility is sensitive to PLS threshold values and PLS correlation parameters.

scholarly journals Dynamic Damage Mechanism and Seismic Fragility Analysis of an Aqueduct Structure

2021 ◽  
Vol 11 (24) ◽  
pp. 11709
Author(s):  
Xinyong Xu ◽  
Xuhui Liu ◽  
Li Jiang ◽  
Mohd Yawar Ali Khan
Keyword(s):  
Ground Motion ◽  
Structural Damage ◽  
Large Scale ◽  
Seismic Analysis ◽  
Fragility Curves ◽  
Limit State ◽  
Fragility Analysis ◽  
Seismic Fragility ◽  
Exceedance Probability ◽  
Computation Efficiency

The Concrete Damaged Plasticity (CDP) constitutive is introduced to study the dynamic failure mechanism and the law of damage development to the aqueduct structure during the seismic duration using a large-scale aqueduct structure from the South-to-North Water Division Project (SNWDP) as a research object. Incremental dynamic analysis (IDA) and multiple stripe analysis (MSA) seismic fragility methods are introduced. The spectral acceleration is used as the scale of ground motion record intensity measure (IM), and the aqueduct pier top offset ratio quantifies the limit of structural damage measure (DM). The aqueduct structure’s seismic fragility evaluation curves are constructed with indicators of different seismic intensity measures to depict the damage characteristics of aqueduct structures under different seismic intensities through probability. The results show that penetrating damage is most likely to occur on both sides of the pier cap and around the pier shaft in the event of a rare earthquake, followed by the top of the aqueduct body, which requires the greatest care during an earthquake. The results of two fragility analysis methodologies reveal that the fragility curves are very similar. The aqueduct structure’s first limit state level (LS1) is quite steep and near the vertical line, indicating that maintaining the excellent condition without damage in the seismic analysis will be challenging. Except for individual results, the overall fragility results are in good agreement, and the curve change rule is the same. The exceedance probability in the case of any ground motion record IM may be estimated using only two factors when using the MSA approach, and the computation efficiency is higher. The study of seismic fragility analysis methods in this paper can provide a reference for the seismic safety evaluation of aqueducts and similar structures.

scholarly journals Seismic Fragility Analysis of Buildings Based on Double-Parameter Damage Models considering Soil-Structure Interaction

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Panpan Zhai ◽  
Peng Zhao ◽  
Yang Lu ◽  
Chenying Ye ◽  
Feng Xiong
Keyword(s):  
Soil Structure ◽  
Fragility Curves ◽  
Damage Index ◽  
Fragility Analysis ◽  
Soil Structure Interaction ◽  
Seismic Fragility ◽  
Rc Buildings ◽  
Structure Interaction ◽  
Damage Models ◽  
Fixed Model

Most conventional seismic fragility analyses of RC buildings usually ignore or greatly simplify the soil-structure interaction (SSI), and the maximum interstory drift ratio (MIDR) is often adopted to establish seismic fragility curves. In this work, an eight-story RC building was designed to study the influence of the SSI on the seismic fragility of RC buildings. Three double-parameter damage models (DPDMs) were considered for the fragility assessment: the Park–Ang model, the Niu model, and the Lu–Wang model. Results show that considering SSI induces a higher fragility than that of the fixed model and that employing the DPDMs for the fragility analysis provides more reasonable results than those evaluated using the MIDR damage index.

Fragility analysis of self-centering prestressed concrete bridge pier with external aluminum dissipators

2016 ◽  
Vol 20 (8) ◽  
pp. 1210-1222 ◽  
Author(s):  
Zhiliang Cao ◽  
Hao Wang ◽  
Tong Guo
Keyword(s):  
Reinforced Concrete ◽  
Prestressed Concrete ◽  
Fragility Curves ◽  
Limit State ◽  
Seismic Capacity ◽  
External Energy ◽  
Limit States ◽  
Performance Limit ◽  
Residual Drift ◽  
Capacity Evaluation

A novel self-centering prestressed concrete pier with external energy dissipators has been developed to realize seismic resilient performance and enhanced corrosion-resisting property. Self-centering capacity of the pier is provided by the unbonded post-tensioned tendons and damage is mostly concentrated on the replaceable dissipators. To investigate the seismic behavior of the proposed pier, a detailed analytical model considering interface opening and dissipator deformation was developed and verified through existing cyclic load tests. Based on the proposed model, a prototype reinforced concrete pier and a self-centering prestressed concrete pier with similar backbone curves are designed, and fragility analyses are conducted on the two piers through incremental dynamic analysis. One maximum drift-based performance limit state (i.e. collapse prevention) and two residual drift-based performance limit states (i.e. emergent usage and reconstruction) are defined for seismic capacity evaluation. Fragility curves indicate that the self-centering prestressed concrete pier has a slightly higher peak drift demand owing to its inferior dissipating capacity as compared with the reinforced concrete pier, while sustains a much lower residual drift demand due to its inherent self-centering characteristic.

scholarly journals Seismic Fragility Analysis of High Earth-Rockfill Dams considering the Number of Ground Motion Records

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Congcong Jin ◽  
Shichun Chi
Keyword(s):  
Ground Motion ◽  
Fragility Curves ◽  
Damage Index ◽  
Fragility Analysis ◽  
Seismic Fragility ◽  
Settlement Rate ◽  
Earthquake Records ◽  
Rockfill Dam ◽  
Ground Motion Records ◽  
The Impact

This study analyzes the impact of the number of ground motions on the seismic fragility of a high earth-rockfill dam and the estimation of reasonable fragility parameters based on a sufficient number of earthquake records. In this paper, the vertical deformation is obtained using the three-dimensional finite element program DYNE3WAC combined with the Pastor–Zienkiewicz–Chan model and Biot dynamic consolidation theory. The relative seismic settlement rate is considered the damage index for the seismic fragility analysis of the dam. The fragility curves of the high earth-rockfill dam are determined by the multiple stripe analysis (MSA) method. A set of seismic waves is chosen based on the spectrum in the Chinese hydraulic structure seismic code. With an increasing number of earthquake records, the coefficients of variation (COV) of the mean and standard deviation (STD) of the relative seismic settlement rate decrease and tend to stabilize when the number of earthquake records reaches 34. The estimated fragility parameters θ and β are constant when the number of earthquake records exceeds 34. The requisite number of earthquake records for an accurate fragility estimation is determined by analyzing the lower and upper confidence intervals for the estimated θ and β. The 95% and 90% confidence interval can accurately estimate the fragility of a high earth-rockfill dam when the number of ground motion records reaches 36 and 32, respectively. The results of the fragility analysis demonstrate that the DYNE3WAC program and MSA method can provide an effective basis for determining fragility curves. Furthermore, the sensitivity analysis of earthquake records is essential for assessing the seismic fragility of high earth-rockfill dams.

On the Seismic Fragility Assessment of Concrete Gravity Dams in Eastern Canada

2019 ◽  
Vol 35 (1) ◽  
pp. 211-231 ◽  
Author(s):  
Rocio Segura ◽  
Carl Bernier ◽  
Ricardo Monteiro ◽  
Patrick Paultre
Keyword(s):  
Ground Motion ◽  
Fragility Curves ◽  
Limit State ◽  
Selection Method ◽  
Probabilistic Methods ◽  
Fragility Analysis ◽  
Gravity Dams ◽  
Limit States ◽  
Eastern Canada

In recent years, probabilistic methods, such as fragility analysis, have emerged as reliable tools for the seismic assessment of dam-type structures. These methods require the selection of a representative suite of ground motion records, resulting in the need for a ground motion selection method that includes all the relevant ground motion parameters in the fragility analysis of this type of structure. This article presents the development of up-to-date fragility curves for the sliding limit states of gravity dams in Eastern Canada using a record selection method based on the generalized conditional intensity measure approach. These fragility functions are then combined with the recently developed regional hazard data to evaluate the annual risk, which is measured in terms of the unconditional probability of limit state exceedance. The proposed methodology is applied to a case study dam in northeastern Canada, whose fragility is assessed through comparison with previous studies and current safety guidelines. It is observed that the more accurate procedure proposed herein produces less conservative fragility estimates for the case study dam.

scholarly journals Fragility and Vulnerability Analysis of an RC Building with the Application of Nonlinear Analysis

Buildings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 390
Author(s):  
Radomir Folić ◽  
Miloš Čokić
Keyword(s):  
Comparative Analysis ◽  
Structural Damage ◽  
Fragility Curves ◽  
Response Spectrum ◽  
Damage Index ◽  
Fragility Analysis ◽  
Elastic Response ◽  
Damage State ◽  
Damage States ◽  
Rc Building

In this paper, the seismic response of a five-story reinforced concrete (RC) frame system building is analysed through fragility analysis. The structure is designed in accordance with structural Eurocodes EN1990, EN1991, EN1992 and EN1998, as a high-ductility (DCH) system. For the analysis of the response of a structural system to earthquake actions, the methods of nonlinear static (NSA) and nonlinear dynamic analyses (NDA) are applied and, based on the obtained results, fragility curves are constructed using statistical methods. A relationship between the intensity measure (IM) and engineering demand parameters (EDPs) is needed in order to estimate a fragility curve. Fragility functions represent a possibility for different states of damage to occur in a certain structural systems at the observed value of the specified IM. Ten accelerograms, used in NDA, are selected and scaled, according to EN1998 provisions, for the chosen elastic response spectrum and referent PGA. Obtained results are used for the statistical analysis and construction of fragility curves. Structural damage state threshold parameters are determined based on the Park and Ang modified damage index methodology and provisions given in FEMA, HAZUS, VISION 2000 and EN codes. Comparative analysis of the structural damage probability for the analysed RC building, calculated using different methodologies to determine damage states, is applied. The fragility analysis results showed the difference between the probabilities of the damage states to occur when different calculation methods are used. This reflects on the assessment of vulnerability curves as well. The obtained results, calculated using different methods, are analysed using comparative analysis.

Comparison of steel frames with RWS and WFP beam-to-column connections through seismic fragility analysis

2020 ◽  
pp. 136943322097728
Author(s):  
Haoran Yu ◽  
Weibin Li
Keyword(s):  
Limit State ◽  
Pushover Analysis ◽  
Steel Frames ◽  
Fragility Analysis ◽  
Structural Safety ◽  
Seismic Fragility ◽  
Fe Modelling ◽  
Collapse Resistance ◽  
Seismic Collapse ◽  
Probabilistic Seismic Demand

Reduced web section (RWS) connections and welded flange plate (WFP) connections can both effectively improve the seismic performance of a structure by moving plastic hinges to a predetermined location away from the column face. In this paper, two kinds of steel frames—with RWS connections and WFP connections—as well as different frames with welded unreinforced flange connections were studied through seismic fragility analysis. The numerical simulation was conducted by using multiscale FE modelling. Based on the incremental dynamic analysis and pushover analysis methods, probabilistic seismic demand analysis and seismic capability analysis were carried out, respectively. Finally, combined with the above analysis results, probabilistic seismic fragility analysis was conducted on the frame models. The results showed that the RWS connection and WFP connection (without double plates) have little influence on reducing the maximum inter-storey drift ratio under earthquake action. RWS connections slightly reduce the seismic capability in non-collapse stages and improve the seismic collapse resistance of a structure, which exhibits good structural ductility. WFP connections can comprehensively improve the seismic capability of a structure, but the seismic collapse resistance is worse than that of RWS connections when the structure has a large number of storeys. The frame with WFP connections has a lower failure probability at every seismic limit state, while the frame with RWS connections sacrifices some of its structural safety in non-collapse stages to reduce the collapse probability.

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