Fragility Analysis Methods for Steel Storage Tanks in Seismic Prone Areas

2016 ◽  
Author(s):  
Hoang Nam Phan ◽  
Fabrizio Paolacci ◽  
Silvia Alessandri
Keyword(s):  
Seismic Vulnerability ◽  
Structural Response ◽  
Response Analysis ◽  
Seismic Demand ◽  
Fragility Functions ◽  
Storage Tanks ◽  
Demand Model ◽  
Limit States ◽  
Environmental Consequences ◽  
Fragility Function

Catastrophic failure of above ground storage tanks was observed due to past earthquakes causing serious economic and environmental consequences. Therefore, the evaluation of the seismic vulnerability of existing liquid storage tanks located in seismic prone areas is an important task. Seismic fragility functions are useful tools in order to quantify the seismic vulnerability of structures. These functions give a probability that a seismic demand on a structural component meets or exceeds its capacity, and are generally derived by a variety of approaches, e.g., field observations of damage, static structural analyses, judgment, or analytical fragility functions. Unlike the other methods, the analytical fragility functions are developed from a coupling of the structural response analysis and a probabilistic seismic demand model. The objective of this study is to investigate the seismic vulnerability of above ground steel storage tanks using different analytical methods of the fragility function. A comparison of the well-known cloud method and the incremental dynamic analysis is performed at different limit states for two existing cylindrical steel storage tanks. The first tank represents a slender geometry with a fixed-roof and the second one is a broad tank, unanchored, and provided with a floating roof.

scholarly journals Seismic Vulnerability Evaluation of a Three-Span Continuous Beam Railway Bridge

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Chongwen Jiang ◽  
Biao Wei ◽  
Dianbin Wang ◽  
Lizhong Jiang ◽  
Xuhui He
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Seismic Isolation ◽  
Seismic Vulnerability ◽  
Element Model ◽  
Seismic Demand ◽  
Continuous Beam ◽  
Railway Bridge ◽  
Demand Model ◽  
Probabilistic Seismic Demand

In order to evaluate the seismic vulnerability of a railway bridge, a nonlinear finite element model of typical three-span continuous beam bridge on the Sichuan-Tibet railway in China was built. It further aimed at performing a probabilistic seismic demand analysis based on the seismic performance of the above-mentioned bridge. Firstly, the uncertainties of bridge parameters were analyzed while a set of finite element model samples were formulated with Latin hypercube sampling method. Secondly, under Wenchuan earthquake ground motions, an incremental dynamic method (IDA) analysis was performed, and the seismic peak responses of bridge components were recorded. Thirdly, the probabilistic seismic demand model for the bridge principal components under the prerequisite of two different kinds of bearing, with and without seismic isolation, was generated. Finally, comparison was drawn to further ascertain the effect of two different kinds of bearings on the fragility components. Based on the reliability theory, results were presented concerning the seismic fragility curves.

Analysis of Seismic Fragility Functions of Highway Embankments

2020 ◽  
Author(s):  
Balázs Hübner ◽  
András Mahler
Keyword(s):  
Finite Element ◽  
Earthquake Engineering ◽  
Seismic Fragility ◽  
Response Analysis ◽  
Fragility Functions ◽  
Ground Response ◽  
Ground Response Analysis ◽  
Fragility Function ◽  
Damage States ◽  
Log Normal

Vulnerability assessment of structures is a vitally important topic among earthquake engineering researchers. Generally, their primary focus is on the seismic performance of buildings. Less attention is paid to geotechnical structures, even though information about the performance of these structures (e.g. road embankments, levees, cuts) during an earthquake is essential for planning remediation and rescue efforts after disasters. In this paper the seismic fragility functions of a highway embankment are defined following an analytical methodolgy. The technique is a displacement-based evaluation of seismic vulnerability. Displacements of an embankment during a seismic event are approximated by a 2-D nonlinear ground response analysis using the finite element method. The numerical model was calibrated based on the results of a 1-D nonlinear ground response analysis. The expected displacements were calculated for 3 different embankment heights and Peak Ground Acceleration (PGA) values between 0,05 and 0,35g. Based on the results of the 2-D finite element analysis, the relationship between displacements and different seismic intensity measures (PGA, Arias-intensity) was investigated. Different damage states were considered, and the probability of their exceedance was investigated. The seismic fragility functions of the embankments were developed based on probability of exceedance of these different damage states based on a log-normal fragility function. The legitimacy of using a log-normal fragility function is also examined.

scholarly journals Seismic Response Analysis and Evaluation of Laminated Rubber Bearing Supported Bridge Based on the Artificial Neural Network

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Bingzhe Zhang ◽  
Kehai Wang ◽  
Guanya Lu ◽  
Weizuo Guo
Keyword(s):  
Seismic Response ◽  
Seismic Damage ◽  
Response Analysis ◽  
Seismic Demand ◽  
Vertical Load ◽  
Demand Model ◽  
Seismic Response Analysis ◽  
Seismic Demands ◽  
Seismic Demand Model ◽  
Rubber Bearings

Laminated rubber bearings are commonly adopted in small-to-medium span highway bridges in earthquake-prone areas. The accurate establishment of the mechanical model of laminated rubber bearings is one of most critical steps for the bridge seismic response analysis. A new constitutive model of bearing based on the artificial neural network (ANN) technique is established through the static cyclic test of laminated rubber bearings, considering the bearing initial stiffness, friction coefficient, and other parameters such as the bearing sectional area, height, loading velocity, vertical load, and aging time. Combined with the ANN method, the ANN-based bridge seismic demand model is built and applied to the rapid evaluation of the bridge seismic damage. The importance of the bearing affecting design factors in the bridge seismic demands are ranked. The results demonstrated that the dimensions of the bearing and vertical load are the main factors affecting the bearings constitutive model. Based on the partial dependency analysis with the ANN-based bridge seismic demand model, it is concluded that the height of bearing is the key design parameter which affects the bridge seismic response the most. The ANN seismic demands model can fit the complex function relationship between various factors and bridge seismic response with high precision, so as to achieve the rapid evaluation of bridge seismic damage.

Prediction of Global Loads and Structural Response Analysis on a Multi-Purpose Semi-Submersible

2005 ◽  
Author(s):  
Yongwon Lee ◽  
Atilla Incecik ◽  
Hoi-Sang Chan
Keyword(s):  
Structural Response ◽  
Paper Analysis ◽  
Dynamic Loads ◽  
Response Analysis ◽  
Marine Structures ◽  
Flat Panel ◽  
Limit States ◽  
Static Loads ◽  
Wave Induced ◽  
Ultimate Limit

This paper presents analysis procedures of a prototype semi-submersible which consists of rectangular pontoons and square columns. The proposed semi-submersible is based on standard cubic boxes constructed by stiffened flat panel line assembly techniques. The prediction of global loads and responses is of great importance to engineers for assessing the safety of marine structures. In this paper analysis methods to determine the global structural loads and to assess the viability of the multi-purpose semi-submersible are described. Static loads in the still water condition and wave induced dynamic loads of cylindrical members in different design conditions were determined to investigate the viability of the proposed semi-submersible. Further the assessment of the safety against failure due to excessive maximum loads was accomplished in ultimate limit states.

Epistemic Uncertainties in Component Fragility Functions

2010 ◽  
Vol 26 (1) ◽  
pp. 41-62 ◽  
Author(s):  
Brendon A. Bradley
Keyword(s):  
Quality Assurance ◽  
Earthquake Engineering ◽  
Epistemic Uncertainty ◽  
Finite Size ◽  
Seismic Demand ◽  
Fragility Functions ◽  
Seismic Performance Assessment ◽  
Fragility Function ◽  
Documentation Quality ◽  
Performance Based Earthquake Engineering

This paper is concerned with the inclusion of epistemic uncertainties in component fragility functions used in performance-based earthquake engineering. Conventionally fragility functions, defining the probability of incurring at least a specified level of damage for a given level of seismic demand, are defined by a mean and standard deviation and assumed to have a lognormal distribution. However, there exist many uncertainties in the development of such fragility functions. The sources of epistemic uncertainty in fragility functions, their consideration, combination, and propagation are presented and discussed. Two empirical fragility functions presented in literature are used to illustrate the epistemic uncertainty in the fragility function parameters due to the finite size of the datasets. These examples and the associated discussions illustrate that the magnitude of epistemic uncertainties are significant and there are clear benefits of the consideration of epistemic uncertainties pertaining to the documentation, quality assurance, implementation, and updating of fragility functions. Epistemic uncertainties should therefore always be addressed in future fragility functions developed for use in seismic performance assessment.

scholarly journals Some Remarks on the Seismic Demand Estimation in the Context of Vulnerability Assessment of Large Steel Storage Tank Facilities

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Antonio Di Carluccio ◽  
Giovanni Fabbrocino
Keyword(s):  
Dynamic Analysis ◽  
Seismic Behavior ◽  
Demand Estimation ◽  
Seismic Demand ◽  
Storage Tanks ◽  
Limit States ◽  
Shell Buckling ◽  
Compressive Stresses ◽  
Steel Tanks ◽  
Base Displacement

The seismic behavior of steel tanks is relevant in industrial risk assessment because collapse of these structures may trigger other catastrophic phenomena due to loss of containment. Therefore, seismic assessment should be focused on for leakage-based limit states. From a seismic structural perspective, damages suffered by tanks are generally related to large axial compressive stresses, which can induce shell buckling near the base and large displacements of unanchored structures resulting in the detachment of piping. This paper approaches the analysis of seismic response of sliding, nonuplifting, unanchored tanks subject to seismic actions. Simplified methods for dynamic analysis and seismic demand estimation in terms of base displacement and compressive shell stress are analyzed. In particular, attention is focussed on some computational issues related to the solution of the dynamic problem and on the extension of the incremental dynamic analysis (IDA) technique to storage tanks.

Displacement-Based Fragility Curves for Seismic Assessment of Adobe Buildings in Cusco, Peru

2012 ◽  
Vol 28 (2) ◽  
pp. 759-794 ◽  
Author(s):  
Nicola Tarque ◽  
Helen Crowley ◽  
Rui Pinho ◽  
Humberto Varum
Keyword(s):  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Response Spectrum ◽  
Limit State ◽  
Seismic Demand ◽  
Limit States ◽  
Plane Failure ◽  
Displacement Capacity ◽  
Out Of Plane ◽  
Displacement Based

The seismic vulnerability of single-story adobe dwellings located in Cusco, Peru, is studied based on a mechanics-based procedure, which considers the analysis of in-plane and out-of-plane failure mechanisms of walls. The capacity of each dwelling is expressed as a function of its displacement capacity and period of vibration and is evaluated for different limit states to damage. The seismic demand has been obtained from several displacement response spectral shapes. From the comparison of the capacity with the demand, probabilities of limit state exceedance have been obtained for different PGA values. The results indicate that fragility curves in terms of PGA are strongly influenced by the response spectrum shape; however, this is not the case for the derivation of fragility curves in terms of limit state spectral displacement. Finally, fragility curves for dwellings located in Pisco, Peru, were computed and the probabilities of limit state exceedance were compared with the data obtained from the 2007 Peruvian earthquake.

scholarly journals A Seismic Demand Model for Bridges Based on IM and EDP Parameter Matching and Bidirectional Optimization

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Shuai Wang ◽  
Shuai Song ◽  
Gang Wu
Keyword(s):  
Correlation Coefficient ◽  
Seismic Vulnerability ◽  
Pearson Correlation ◽  
Vulnerability Analysis ◽  
Seismic Demand ◽  
Demand Model ◽  
Demand Models ◽  
Wide Range ◽  
Seismic Demand Model ◽  
Seismic Vulnerability Analysis

The accuracy of seismic demand models in seismic vulnerability analysis of structures or components mainly depends on the seismic intensity measures (IMs) and engineering demand parameters (EDPs). This paper proposes a novel method to obtain the optimal seismic demand model for the seismic vulnerability analysis of bridges. The method obtains the IM-EDP combination by matching all IMs and EDPs within a wide range one by one, considering the contribution of multiple IM parameters to the seismic response of the structure and avoiding the blindness of EDP selection. The IM is determined by calculating Pearson correlation coefficient and partial correlation coefficient, controlling the correlation between EDP and IM (or IMs) to a minimum to reduce the multicollinearity within the vector IMs and avoid ill-conditioned models. The optimal seismic demand model is obtained by inspecting the scatter plot and residual plot of suboptimal seismic demand models determined from all combinations by guaranteeing efficiency and sufficiency. The efficiency of seismic demand models is guaranteed by controlling the root mean square error (RMSE) and the coefficient of determination (R2). The sufficiency of models is guaranteed by controlling the slope of fitted line. A continuous rigid frame bridge with double thin-walled piers is used as a case study and a dynamic time-history analysis is performed to obtain the seismic vulnerability of bridge with the proposed method. The results show that the proposed method is feasible and ideally suited for optimizing seismic demand model.

scholarly journals Seismic Vulnerability Assessment and Simplified Empirical Formulation for Predicting the Vibration Periods of Structural Units in Aggregate Configuration

Geosciences ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 287
Author(s):  
Nicola Chieffo ◽  
Antonio Formisano ◽  
Giovanni Mochi ◽  
Marius Mosoarca
Keyword(s):  
Risk Factor ◽  
Seismic Vulnerability ◽  
Structural Response ◽  
Vibration Modes ◽  
Fragility Functions ◽  
Structural Units ◽  
Vibration Period ◽  
Seismic Vulnerability Assessment ◽  
Modelling Techniques ◽  
Historical Center

The present research aims at investigating the vibration period of structural units (SUs) of a typical masonry aggregate located in the historical center of Mirandola, a municipality in the province of Modena. The clustered building consists of eighteen SUs mutually interconnected to each other, which are characterized by solid brick walls and deformable floors. First of all, non-linear static analyses are performed by adopting the 3Muri software focusing on two distinct modelling techniques concerning the analyzed SUs in isolated and clustered configurations. Congruently to the procedure adopted, in order to evaluate a reliable seismic structural response of the SUs arranged in aggregate conditions, the contribution in terms of stiffness and mass derived from adjacent buildings is considered. The analysis results are represented in terms of risk factor, stiffness, and ductility. Secondly, the eigenvalue analysis is faithfully developed to identify the main vibration modes of the investigated SUs by proposing an empirical formulation, that allows for predicting the vibration period of structural units placed in aggregate configuration starting from the corresponding isolated ones. Finally, fragility functions are derived for both the heading and intermediate SUs to point out the expected damages under earthquakes with different intensities.

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