Seismic Fragility Analysis of a Water Storage Structure

2004 ◽  
Author(s):  
K. Bhargava ◽  
A. K. Ghosh ◽  
S. Ramanujam
Keyword(s):  
Seismic Analysis ◽  
Water Storage ◽  
Structural Response ◽  
Seismic Fragility ◽  
Material Strength ◽  
Structural Damping ◽  
Ground Acceleration ◽  
Storage Structure ◽  
Hydrodynamic Effects

The present paper is concerned with the seismic response and fragility evaluation of a water storage structure. Seismic analysis has been carried out considering the hydrodynamic effects of the contained water. The various parameters that could affect the seismic structural response include material strength of concrete, structural damping available within the structure and the normalized ground motion response spectral shape. Based on this limited case study; the seismic fragility of the structure is developed as families of conditional probability curves plotted against peak ground acceleration (PGA) at the location of interest. The procedure adopted incorporates the various randomness and uncertainty associated with the parameters under consideration.

Seismic Fragility Analysis of a Water Storage Structure

2005 ◽  
Vol 127 (4) ◽  
pp. 502-507
Author(s):  
Kapilesh Bhargava ◽  
A. K. Ghosh ◽  
S. Ramanujam
Keyword(s):  
Seismic Vulnerability ◽  
Seismic Analysis ◽  
Water Storage ◽  
Structural Response ◽  
Seismic Fragility ◽  
Material Strength ◽  
Ground Acceleration ◽  
Storage Structure ◽  
Modes Of Failure ◽  
Hydrodynamic Effects

Probabilistic seismic risk assessment (PSRA) of a structure is essential to identify the seismic vulnerability of structural members associated with the different stages of damage. Seismic fragility evaluation is a widely accepted approach to develop seismic vulnerability information for the structures. The present paper is concerned with the seismic response and fragility evaluation of a water storage structure. Seismic analysis has been carried out considering the hydrodynamic effects of the contained water. For seismic fragility evaluation, the various parameters that could affect the seismic structural response have been identified as material strength of concrete, structural damping available within the structure, and the normalized ground motion response spectral shape. Based on this limited case study, the seismic fragility of the structure is developed as families of conditional probability curves plotted as a function of peak ground acceleration at the location of interest. The paper presents the method adopted for the seismic fragility evaluation that incorporates the various randomness and uncertainty associated with the parameters under consideration. Typical results of fragility have been presented for different stresses, i.e., corresponding to the different modes of failure. The results of the fragility study show that the seismic structural response at the location of interest is quite sensitive to the randomness and uncertainty associated with the variable parameters considered in the present study. These results will be useful for PSRA studies.

Seismic Hazard Analysis for an NPP Site

2004 ◽  
Author(s):  
A. K. Ghosh ◽  
H. S. Kushwaha
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Peak Ground Acceleration ◽  
Hazard Analysis ◽  
Structural Response ◽  
Response Spectra ◽  
Seismic Fragility ◽  
Material Strength ◽  
Ground Acceleration ◽  
Hazard Response

The various uncertainties and randomness associated with the occurrence of earthquakes and the consequences of their effects on the NPP components and structures call for a probabilistic seismic risk assessment (PSRA). However, traditionally, the seismic design basis ground motion has been specified by normalised response spectral shapes and peak ground acceleration (PGA). The mean recurrence interval (MRI) used to be computed for PGA only. The present work develops uniform hazard response spectra i.e. spectra having the same MRI at all frequencies for Kakrapar Atomic Power Station site. Sensitivity of the results to the changes in various parameters has also been presented. These results determine the seismic hazard at the given site and the associated uncertainties. The paper also presents some results of the seismic fragility for an existing containment structure. The various parameters that could affect the seismic structural response include material strength of concrete, structural damping available within the structure and the normalized ground motion response spectral shape. Based on this limited case study the seismic fragility of the structure is developed. The results are presented as families of conditional probability curves plotted against the peak ground acceleration (PGA). The procedure adopted incorporates the various randomness and uncertainty associated with the parameters under consideration.

Static Analysis of Gravity Dams Considering Foundation-Structure Interaction

2016 ◽  
Vol 857 ◽  
pp. 237-242
Author(s):  
Margaret Abraham ◽  
Bennet Kuriakose ◽  
Reni Kuruvilla
Keyword(s):  
Numerical Model ◽  
Structural Design ◽  
Seismic Analysis ◽  
Structural Response ◽  
Fluid Structure Interactions ◽  
Gravity Dams ◽  
Structure Interaction ◽  
Optimum Depth ◽  
Foundation Structure

A dam is an artificial barrier constructed across a stream channel to impound water. Analysis of stresses and displacements are inevitable for the structural design and failure analysis of dams. This paper deals with the numerical simulation of structural response of gravity dams, duly considering the foundation-structure interaction. The optimum depth and width of foundation extend to be considered in the numerical model is also studied. A parametric study based on the stiffness of the foundation is also exercised. As an application of the developed model, a case study of Peechi gravity dam is presented. This study proved the importance of consideration of foundation-structure interaction in the structural analysis of dams. The developed numerical model can be further improved for performing seismic analysis of gravity dams, considering the foundation-structure as well as fluid-structure interactions.

On Ground Motion Intensity Indices

2007 ◽  
Vol 23 (1) ◽  
pp. 147-173 ◽  
Author(s):  
Rafael Riddell
Keyword(s):  
Ground Motion ◽  
Seismic Analysis ◽  
Structural Response ◽  
Frequency Range ◽  
Ground Acceleration ◽  
Essential Point ◽  
Sensitive Region ◽  
Peak Ground Motion ◽  
Degradation Models

The characterization of strength of earthquake demands for seismic analysis or design requires the specification of a level of intensity. Numerous ground motion intensity indices that have been proposed over the years are being used for normalizing or scaling earthquake records regardless of their efficiency. An essential point of this study is that a ground motion index is appropriate, or efficient, as long as it can predict the level of structural response. This study presents correlations between 23 ground motion intensity indices and four response variables: elastic and inelastic deformation demands, and input energy and hysteretic energy; nonlinear responses are computed using elastoplastic, bilinear, and bilinear with stiffness degradation models. As expected, no index is found to be satisfactory over the entire frequency range. Indeed, indices related to ground acceleration rank better in the acceleration-sensitive region of the spectrum; indices based on ground velocity are better in the velocity-sensitive region and, correspondingly, generally occur in the displacement-controlled region. Despite frequent criticism, the peak ground motion parameters passed the test successfully. A ranking of indices is presented, thus providing a choice of the most appropriate one for a particular application in the frequency range of interest.

scholarly journals Kriging Metamodel-Based Seismic Fragility Analysis of Single-Bent Reinforced Concrete Highway Bridges

Buildings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 238
Author(s):  
Phuong Hoa Hoang ◽  
Hoang Nam Phan ◽  
Duy Thao Nguyen ◽  
Fabrizio Paolacci
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Fragility Curves ◽  
Structural Response ◽  
Highway Bridges ◽  
Fragility Analysis ◽  
Seismic Fragility ◽  
Kriging Metamodel ◽  
Different Sources

Uncertainty quantification is an important issue in the seismic fragility analysis of bridge type structures. However, the influence of different sources of uncertainty on the seismic fragility of the system is commonly overlooked due to the costly re-evaluation of numerical model simulations. This paper aims to present a framework for the seismic fragility analysis of reinforced concrete highway bridges, where a data-driven metamodel is developed to approximate the structural response to structural and ground motion uncertainties. The proposed framework to generate fragility curves shows its efficiency while using a few finite element simulations and accounting for various modeling uncertainties influencing the bridge seismic fragility. In this respect, a class of single-bent bridges available in the literature is taken as a case study, whose three-dimensional finite element model is established by the OpenSees software framework. Twenty near-source records from different sources are selected and the Latin hypercube method is applied for generating the random samples of modeling and ground motion parameters. The Kriging metamodel is then driven on the structural response obtained from nonlinear time history analyses. Component fragility curves of the reinforced concrete pier column are derived for different damage states using the Kriging metamodel whose parameters are established considering different modeling parameters generated by Monte Carlo simulations. The results demonstrate the efficiency of the proposed framework in interpolating the structural response and deriving the fragility curve of the case study with any input conditions of the random variables.

Seismic Analysis Considering Soil-Structure Interaction

2004 ◽  
Author(s):  
Gangadhara Tilak Dulam ◽  
R. Sundaravadivelu
Keyword(s):  
Storage Tank ◽  
Soil Structure ◽  
Seismic Analysis ◽  
Soil Structure Interaction ◽  
Single Pile ◽  
Spectral Acceleration ◽  
Ground Acceleration ◽  
Structure Interaction ◽  
Different Levels

The case study on LNG storage tank, Inchon, Korea which is supported by pile foundation system is carried out using Abaqus. The dynamic analysis is carried out on a single pile of this storage tank varying the ground accelerations, as 0.08g, 0.18g, 0.28g and 0.38g and maintaining the duration constant as 25 s. The spectral acceleration at the different levels of the piles are used to obtain the transfer function which is the ratio of spectral acceleration of the pile to ground acceleration. This paper will present the seismic response of single pile subjected to an earthquake at its bottom.

scholarly journals Seismic Assessment of Steel MRFs by Cyclic Pushover Analysis

2019 ◽  
Vol 13 (1) ◽  
pp. 12-26 ◽  
Author(s):  
F. Barbagallo ◽  
M. Bosco ◽  
A. Ghersi ◽  
E.M. Marino ◽  
P.P. Rossi
Keyword(s):  
Local Level ◽  
Pushover Analysis ◽  
Nonlinear Dynamic Analysis ◽  
Structural Response ◽  
Strength Degradation ◽  
Structural Members ◽  
Seismic Behaviour ◽  
Ground Acceleration ◽  
Nonlinear Static

Background:Structural members subjected to strong earthquakes undergo stiffness and strength degradation. To predict accurately the seismic behaviour of structures, nonlinear static methods of analysis have been developed in scientific literature. Generally, nonlinear static methods perform the pushover analysis by applying a monotonic lateral load. However, every earthquake input is characterized by several repeated loads with reverse in signs and the strength and deformation capacities of structures are generally related to the cumulative damage. This aspect is neglected by the conventional monotonic approaches, which tend to overestimate the strength and stiffness of structural members.Objective:This paper aims to investigate the possibility that the Cyclic Pushover Analysis (CPA) may be used as a tool to assess the seismic behaviour of structures. During the CPA, the structure is subjected to a distribution of horizontal forces that is reversed in sign when predefined peak displacements of the reference node are attained. This process repeats in cycles previously determined in a loading protocol.Methods:To investigate the effectiveness of the CPA in predicting the structural response, a steel moment resisting frame is designed as a case study building. A numerical model of this frame is developed in OpenSees. To examine the influence of the loading protocols on the seismic response, the CPA is run following the ATC-24 and the SAC protocols. Additionally, the seismic demand of the case study frame is determined by a Monotonic Pushover Analysis (MPA) and by Incremental nonlinear Dynamic Analysis (IDA).Results and Conclusions:The following results are obtained:• Despite the differences between the SAC and the ATC-24 loading protocols, the CPA applied according to those two protocols led to almost the same structural response of the case study frame.• The CPA showed the capability of catching the stiffness and strength degradation, which is otherwise neglected by the MPA. In fact, given a base shear or peak ground acceleration, the CPA leads to the estimation of larger displacement demands compared to the MPA.• During long (or medium) duration earthquakes, the CPA was necessary to estimate accurately the response of the structure. In fact, at a PGA equal to 1 g, the CPA estimated the top displacement demand with an error lower than 10%, while the MPA underestimated it by 18%.• The importance of considering the cyclic deterioration is shown at local level by the damage indexes of the frame. In the case of long earthquakes, given a top displacement of 600 mm (corresponding to a PGA equal to 1 g), the CPA estimated the damage indexes with an error equal to 12%.

scholarly journals Regression Models for Soil Water Storage Estimation Using the ESA CCI Satellite Soil Moisture Product: A Case Study in Northeast Portugal

Water ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 37
Author(s):  
Tomás de Figueiredo ◽  
Ana Caroline Royer ◽  
Felícia Fonseca ◽  
Fabiana Costa de Araújo Schütz ◽  
Zulimar Hernández
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Regression Models ◽  
Meteorological Data ◽  
Water Storage ◽  
Model Performance ◽  
Soil Water Balance ◽  
Soil Water Storage ◽  
The Relationship

The European Space Agency Climate Change Initiative Soil Moisture (ESA CCI SM) product provides soil moisture estimates from radar satellite data with a daily temporal resolution. Despite validation exercises with ground data that have been performed since the product’s launch, SM has not yet been consistently related to soil water storage, which is a key step for its application for prediction purposes. This study aimed to analyse the relationship between soil water storage (S), which was obtained from soil water balance computations with ground meteorological data, and soil moisture, which was obtained from radar data, as affected by soil water storage capacity (Smax). As a case study, a 14-year monthly series of soil water storage, produced via soil water balance computations using ground meteorological data from northeast Portugal and Smax from 25 mm to 150 mm, were matched with the corresponding monthly averaged SM product. Linear (I) and logistic (II) regression models relating S with SM were compared. Model performance (r2 in the 0.8–0.9 range) varied non-monotonically with Smax, with it being the highest at an Smax of 50 mm. The logistic model (II) performed better than the linear model (I) in the lower range of Smax. Improvements in model performance obtained with segregation of the data series in two subsets, representing soil water recharge and depletion phases throughout the year, outlined the hysteresis in the relationship between S and SM.

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