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Endurance time method: Exercise test applied to structures
, Article Asian Journal of Civil Engineering ; Volume 10, Issue 5 , 2009 , Pages 559-577 ; 15630854 (ISSN) ; Tajmir Riahi, H ; Vafai, A ; Sharif University of Technology
Building and Housing Research Center (BHRC)
2009
Abstract
Endurance Time (ET) method is a new dynamic analysis procedure that aims at estimating seismic performance of structures by subjecting them to predesigned intensifying acceleration. These acceleration functions are designed in a way that they approximately simulate earthquakes with different intensities through their duration. Performance of the structure is judged based on its behavior for different intensity measures through time. A set of three acceleration functions have been produced using the ET concept by applying optimization techniques. These acceleration functions are designed in such a way that their response spectrum, while complying with typical code design spectra, intensify...
Experimental and analytical study of block slit damper
, Article Journal of Constructional Steel Research ; Volume 141 , February , 2018 , Pages 167-178 ; 0143974X (ISSN) ; Pournamazian Najafabadi, E ; Esmaeilpour Estekanchi, H ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
This study proposes a novel type of metallic yielding damper called block slit damper or BSD. This damper is a slit damper with very low height to thickness ratio. This device has high shear capacities, and is more economical than SSD devices with high height to thickness ratios. Based on theoretical analysis the formulation for the BSD device's main parameters is derived. Then to investigate the hysteretic behavior of the proposed devices, 5 specimens with different aspect ratios (height-width ratios) were manufactured and tested in a quasi-static manner. The tests revealed that by reducing the aspect ratios, the shear and energy dissipation capacity increases while the displacement...
Predicting probabilistic distribution functions of response parameters using the endurance time method
, Article Structural Design of Tall and Special Buildings ; 2018 ; 15417794 (ISSN) ; Mirfarhadi, S. A ; Esmaeilpour Estekanchi, H ; Vafai, H ; Sharif University of Technology
John Wiley and Sons Ltd
2018
Abstract
The main objective of this study is the development of endurance time (ET) excitations in order to take structural response uncertainty into account for use in performance-based earthquake engineering. There are several uncertainties in earthquake engineering, including earthquake occurrence, structural response, damage, and loss. In the current research, structural response uncertainty is directly included in the ET method, which is an analysis method used for performing structural behavior assessment under seismic actions. Conventional practice of the ET method does not provide any information about seismic response distribution. Despite the simplicity of the ET method, it is an accurate...
Application of Endurance Time Method in Performance-based Design
, M.Sc. Thesis Sharif University of Technology ; Esmaeilpour Estekanchi, Homayun (Supervisor)
Abstract
Endurance Time (ET) method is a dynamic analysis method in which the structure is subjected to an intensifying accelerogram and its response is recorded at different times.On the other hand a new method for designing earthquake resistant structures is Performance-Based Design (P-BD) method. P-BD is a methodology in which structural design criteria are expressed in terms of achieving a set of different performance objectives. In this research the application of ET method and target curve (which is defined based on ET method concepts) in the performance-based design has been studied.Correlating time in ET method and earthquake return period, the design,assessment and retrofitting of different...
Collapse Analysis of Steel Moment Frames Using Endurance Time Method
, M.Sc. Thesis Sharif University of Technology ; Esmaeilpour Estekanchi, Homayun (Supervisor)
Abstract
In Endurance Time method structures are subjected a set of predesigned intensifying excitations. These excitations are produced in a way that their response spectrum, while complying with a specified spectrum, intensifies with time. So they can be used approximately to simulate the average effects of several ground motions scaled to different intensities. In this study applicability of Endurance Time method for evaluating collapse potential of buildings is investigated. A set of steel moment frames is used for collapse assessment. The process of using Endurance Time method in collapse evaluation is explained with consideration of uncertainty effects. collapse fragility curves and collapse...
The Effect of Earthquake Vertical Component on Nonlinear Analysis of Concrete Gravity Dams Using Endurance Time Method
, M.Sc. Thesis Sharif University of Technology ; Esmaeilpour Estekanchi, Homayun (Supervisor)
Abstract
Study of dams' behavior and their safety against earthquakes has been interesting due to the high rate of failure. In the past, this study was just about linear analysis of dams. However, the weakness of concrete in tensile strength results in cracks in body of dams. Therefore, the nonlinear analysis of these huge structures seems to be so important. Many researches have been done in this field to model dam-reservoir-foundation with effects of concrete nonlinearity. In spite of the fact that gravity dams' safety depends on cracking status and consequently on nonlinear behavior of concrete, we cannot reach accurate and suitable results for dynamic behavior of concrete dams because these...
Evaluation of Seismic Behavior of Anchored and Unanchored Tanks By Using Endurance Time Method
,
M.Sc. Thesis
Sharif University of Technology
;
Esmaeilpour Estekanchi, Homayun
(Supervisor)
Abstract
Endurance Time (ET) method is a relatively general analysis method based on time history analysis for evaluation of structure systems under dynamic excitations resulted from earthquakes. Assessment criterion in this method is based on time of endurance of structure versus applied acceleration function and don't use parameters such as stiffness, lateral strength, period of structure and other dynamic characteristics straightly. Upper time of endurance means better operation. In this method, if assumed damage index stays under allowable limit until determined time of endurance then the structure assumed acceptable. In this study, nonlinear analysis of anchored and unanchored (on rigid base)...
Experimental investigation and probabilistic models for residual mechanical properties of GFRP pultruded profiles exposed to elevated temperatures
, Article Composite Structures ; Volume 211 , 2019 , Pages 610-629 ; 02638223 (ISSN) ; Houshmand Khaneghahi, M ; Ahmadie Amiri, H ; Esmaeilpour Estekanchi, H ; Ozbakkaloglu, T ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Here, we investigate the influence of elevated temperatures with negligible ambient oxygen on mechanical properties of various embedded glass fiber reinforced polymer (GFRP) profiles, as well as the application of a predictive Bayesian model for predicting these properties. Both the flexural and compressive properties of FRP profiles were investigated through the tests of I-shaped and box-shaped profiles. To determine the impact of low and high elevated temperature, the profiles were exposed to a wide range of temperatures (i.e., 25–550 °C); effects of the exposure time were also investigated. Experiments showed that specimens exposed to higher elevated temperatures for longer time periods...
Life Cycle Cost Analysis and Comparison Of Concrete Structures with and Without Shear Walls by Endurance Time Method
, M.Sc. Thesis Sharif University of Technology ; Esmaeilpour Estekanchi, Homayun (Supervisor)
Abstract
The actual value of structures should not be evaluated only based on initial cost, because failure cost and economical losses due to corrosion and natural hazards can be catastrophic. When a long life Performance of a structure is expected, life cycle cost analysis is the best way to assess and compare economic value of different design choices. The main purpose of this work is investigating the effect of shear walls in limit state cost and total cost . Results demonstrate that shear walls can reduce limit state cost up to 70 percent . Furthermore the influence of increasing thickness of shear walls and effect of reducing dead loads in total life cycle cost is discussed. It is shown that...
Design & Analyze of Spherical Shell & Pointed Domes by Endurance Time Method
, M.Sc. Thesis Sharif University of Technology ; Esmaeilpour Estekanchi, Homayoon (Supervisor)
Abstract
Monumental structures are cultural and aesthetic bases in every nation, and our duty to maintaining these valuable remnants is obvious clearly. Meanwhile, the vaults have essential role as main elements in the Islamic architecture, and evaluation of their performance as well as retrofitting with regard to placing in earthquake-prone regions has high importance. Therefore, in this dissertation, performance of spherical and pointed domes are evaluated. Hence, 13 traditional Iranian domes are modeled with linear and non-linear material behavior in ABAQUS finite element software to verifying effect of their geometries in seismic performance. Base on Complex behavior of these models, they...
Endurance wave analysis (EWA) and its application for assessment of offshore structures under extreme waves
, Article Applied Ocean Research ; Volume 37 , 2012 , Pages 98-110 ; 01411187 (ISSN) ; Matin Nikoo, H ; Estekanchi, H ; Sharif University of Technology
2012
Abstract
The aim of this paper is to introduce a novel approach, called Endurance Wave Analysis (EWA), for non-linear dynamic analysis and assessment of offshore structures subjected to irregular wave forces. This is, in fact, an extension of the Endurance Time Analysis (ETA) already presented by previous researchers for the seismic assessment of onshore structures. With the EWA method, the offshore structure is simulated under a predefined Intensifying Wave Train Function (IWTF), corresponding to a gradually deteriorating sea state at a specific site. The function is designed so that the roughness of the sea state represented by them increases over the time and even goes well beyond the design sea...
Seismic analysis of steel liquid storage tanks by Endurance Time method
, Article Thin-Walled Structures ; Volume 50, Issue 1 , January , 2012 , Pages 14-23 ; 02638231 (ISSN) ; Alembagheri, M ; Sharif University of Technology
2012
Abstract
Endurance Time (ET) method is a time history based method for seismic evaluation of structures using intensifying dynamic excitation as the loading function. In this paper, application of this method in the analysis of steel tanks has been investigated. A methodology for practical application of ET method in seismic assessment of storage tanks has been presented. This methodology has been applied in three-dimensional nonlinear analysis of a particular anchored steel tank using Finite Element method, and results are compared with conventional codified design procedures. Results of the analyses indicate reasonable accuracy of the proposed method in estimation of seismic responses of steel...
An efficient procedure on the evaluation of the probability distribution function of the cumulative seismic loss
, Article Engineering Structures ; Volume 291 , 2023 ; 01410296 (ISSN) ; Esmailpour Estekanchi, H ; Sharif University of Technology
Elsevier Ltd
2023
Abstract
The existing loss assessment frameworks in the literature are mainly limited to the evaluation of the expected lifetime seismic losses, and do not assess the probability distribution of the long-term losses. The long-term loss is defined as the cumulative seismic loss of the structures over the service life. However, the probability distribution of the long-term losses can also be informative for decision-making under uncertain seismic consequences. This paper proposes an efficient procedure to calculate the probability distribution of the long-term losses. The procedure is based on the discretization of continuous random variables and performing two sets of recursive convolutions. The...
Application of endurance time method in seismic assessment of steel frames
, Article Engineering Structures ; Volume 33, Issue 9 , 2011 , Pages 2535-2546 ; 01410296 (ISSN) ; Riahi, H. T ; Vafai, A ; Sharif University of Technology
2011
Abstract
In this paper, application of a new dynamic procedure called Endurance Time (ET) method in seismic analysis of steel frames is explained. In this method, structures are subjected to gradually intensifying ground shaking and their performance is assessed based on their response considering relevant design criteria at each intensity level. By considerably reducing the number of time history analyses for assessment of structural response at different intensities, this procedure tends to pave a way for practical performance based design of structures. The accuracy of ET method in predicting the response of structures in linear and nonlinear analysis is investigated by considering a set of steel...
Consistent one-bay frame simplified model for efficient seismic evaluation of steel moment frame buildings with equal and unequal bay lengths
, Article Structures ; Volume 34 , December , 2021 , Pages 3345-3362 ; 23520124 (ISSN) ; Ahmadie Amiri, H ; Esmaeil Estekanchi, H ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
A Consistent One-Bay Frame (COBF) simplified model for the efficient estimation of Engineering Demand Parameters (EDPs) in Steel Moment Resisting Frames (SMRFs) with equal and unequal bay lengths is proposed. The geometry of the Substitute One-Bay Frame (SOBF) simplified model has been used, and the elastic and inelastic properties of the beams and columns in this model are determined using an energy consistent approach in a way that the energy balance is established between the members of the original SMRF and the SOBF simplified model. This way, the SOBF simplified model, which originally could only be used for MRFs with equal bay lengths, can now be used for MRFs with any geometric...
Dynamic response of cracked cylindrical shells with internal pressure
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings ; 2002 , Pages 257-265 ; 0791836282 (ISBN); 9780791836286 (ISBN) ; Nayeb Hashemi, H ; Estekanchi, H. E ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2002
Abstract
Sub-surface cracks in pipelines with internal pressure may severely affect their dynamic response. The extreme cases of these cracks are when these cracks go through the thickness of the pipes. Dynamic responses of cracked and un-cracked pipes with fixed ends and under various internal pressures were evaluated experimentally and theoretically. In the experimental part, the effects of pipe internal pressure on the resonant frequencies and damping of the pipe were evaluated. In the theoretical part, finite element analyses were performed to find dynamic response of pipes with various crack length and orientation respect to the axis of the pipe. The experimental results showed resonant...
Optimal damper placement in steel frames by the endurance time method
, Article Structural Design of Tall and Special Buildings ; Volume 20, Issue 5 , 2011 , Pages 612-630 ; 15417794 (ISSN) ; Basim, M. C ; Sharif University of Technology
2011
Abstract
Performance-based optimal seismic design of structures requires repetitive and massive dynamic analyses. In the Endurance Time (ET) method, structures are subjected to specially designed intensifying acceleration functions and their response at various excitation levels is estimated by each single response-history analysis, thus, significantly reducing the required computational demand. In this paper, the ET method is utilized to acquire optimal placement of viscous dampers in short steel frames with the target of obtaining the desirable performance in two hazard levels simultaneously. In the optimization procedure, the damping coefficients of the added dampers are treated as design...
Determination of target time for endurance time method at different seismic hazard levels
, Article Scientia Iranica ; Volume 25, Issue 1 , 2018 , Pages 33-49 ; 10263098 (ISSN) ; Esmaeilpour Estekanchi, H ; Sharif University of Technology
Sharif University of Technology
2018
Abstract
Various durations of Endurance Time Acceleration Functions (ETAFs) associated with different seismic hazard levels are presented to enable Endurance Time (ET) method for use in probabilistic seismic demand assessment studies. Various Intensity Measures (IMs) were, first, considered for establishing multiple "IM-duration" relationships. A set of 30 RC moment resisting frames were, then, subjected to IDA analysis using 44 ground motion records and the median IM values corresponding to different structural response levels were extracted. These values were compared with the ET-derived IMs by computing the errors corresponding to various demand levels and summating these errors over a complete...
A rapid seismic fragility and risk analysis of electrical substation equipment considering modeling uncertainties
, Article Engineering Structures ; Volume 293 , 2023 ; 01410296 (ISSN) ; Ismail Pour Estekanchi, H ; Sharif University of Technology
Elsevier Ltd
2023
Abstract
This study aims to evaluate the influences of modeling-related uncertainties on the seismic response and fragility function of the four vulnerable components of electrical substation equipment, taking into account the dynamic interaction between apparatuses via bus slider-rigid bus conductors. The 3D finite element model for interconnected disconnect switch- circuit breaker-current transformer-surge arrester system is developed in OpenSees software. A sensitivity analysis is conducted to evaluate and rank the importance of individual random variables on the seismic responses. To incorporate modeling uncertainties into the failure fragility function, probabilistic structural interconnected...
Nonlinear Seismic Assessment of Arch Dams and Investigation of Joint Behavior Using Endurance Time Analysis Method
, Article Arabian Journal for Science and Engineering ; Vol. 39, issue. 5 , May , 2014 , p. 3599-3615 ; Mirzabozorg, H ; Estekanchi, H. E ; Sharif University of Technology
2014
Abstract
At the present study, application of endurance time analysis (ETA) method in seismic evaluation of arch dams is investigated. ETA is a time-history based dynamic pushover procedure, which utilizes a set of predesigned intensifying acceleration functions to estimate the responses of the structural systems in various seismic excitation levels. Dez dam was chosen as the case study and all contraction and peripheral joints were modeled based on as-built drawings. The reservoir was modeled as a compressible medium and the foundation was assumed to be massless. Results show that ETA method is able to estimate dynamic responses of the dam with acceptable accuracy in comparison with time history...