Loading...
Search for:
seismic-assessment
0.007 seconds
Total 33 records
Performance-based seismic assessment of steel frames using endurance time analysis
, Article Engineering Structures ; Vol. 69 , 2014 , Pages 216-234 ; ISSN: 01410296 ; Sattar, S ; Estekanchi, H. E ; Sharif University of Technology
Abstract
The current performance-based seismic assessment procedure can be computationally intensive as it requires a large number of time history analyses (THA) each requiring time intensive post-processing of results. This study proposes the endurance time analysis (ETA) method as an alternative method to THA and incremental dynamic analysis (IDA). ETA is a time history based dynamic pushover procedure that applies a set of gradually intensifying acceleration functions to the structure and monitors the performance of the building accordingly. In this paper, the application of ETA in the seismic assessment of multistory steel concentrically braced frames is compared with THA and IDA methods....
Risk based seismic assessment of structures
, Article Advances in Structural Engineering ; Volume 16, Issue 2 , 2013 , Pages 307-314 ; 13694332 (ISSN) ; Tonekaboni, M ; Sharif University of Technology
2013
Abstract
In this paper a new approach to risk based seismic assessment of structures is proposed based on acceptable risk levels. In this approach, the probabilistic seismic vulnerability, predicted lifetime of structure, importance and knowledge factors are considered in the evaluation process. Park & Ang damage index is used to quantify damage states of structure. By performing several incremental dynamic analyses, all damage states of structure from minor to heavy and collapse are considered under all possible ground motions. The structural risk level and the necessity of seismic retrofit measures are specified by seismic risk index of structure. This probabilistic performance based method is...
FEMA approaches in seismic assessment of jacket platforms (case study: Ressalat jacket of Persian gulf)
, Article Journal of Constructional Steel Research ; Volume 65, Issue 10-11 , 2009 , Pages 1979-1986 ; 0143974X (ISSN) ; Tabeshpour, M. R ; Komachi, Y ; Sharif University of Technology
2009
Abstract
The assessment of existing platforms under past environmental (wave, wind, current and etc.) loads and probable future loads (earthquake) is a relatively new process and has not yet been standardized as the design has. This lack of standardization creates some difficulty in establishing performance requirements which must be developed depending upon the risks (i.e., hazards, exposures and consequences) associated with the future operation of the platform. The present criteria of the offshore structure standards for seismic assessment can be improved using Building prestandards. Recently some documents such as FEMA-356 and ATC-40 are developed for seismic assessment of buildings. However...
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...
Seismic Performance Evaluation of Shear Wall Buildings through Nonlinear Dynamic Analysis
, M.Sc. Thesis Sharif University of Technology ; Mofid, Masood (Supervisor)
Abstract
The primary goal of seismic design requirements of building codes is to protect life safety of occupants during severe earthquakes. Thus it is required that collapse probability of designed buildings to be acceptably low. However current design codes are strength based and intrinsically experimental. Thus collapse safety of buildings designed by these codes is not known quantitatively. The history of formation and update of seismic building codes is marked by big earthquakes; often serving as landmarks for the evolution of seismic codes and detecting its deficiencies. As time passes, the design criteria become more and more articulate and ambitious, just as the design objectives evolve from...
Effect of Vertical Component of Earthquake on Cable-stayed Bridges
, M.Sc. Thesis Sharif University of Technology ; Maleki, Shervin (Supervisor)
Abstract
Cable stayed bridges have been used extensively in recent years for long span bridges up to 1000m. Although seismic behavior of these bridges has been researched in the last decade, however, the effect of vertical component of earthquake on cable-stayed bridges has not been studied before. In this thesis, the geometric nonlinear static analyses on dead loads followed by linear direct integration dynamic analyses have been used to study this effect. The results of analyses with three-component earthquakes are compared with two-component earthquakes. Fourteen models of cable-stayed bridges with different main span length, shape of pylons and the deck-pylon connection are employed. The errors...
Assessment of Seismic Retrofit Policies for Buildings
, M.Sc. Thesis Sharif University of Technology ; Kashani, Hamed (Supervisor)
Abstract
Occurrence of natural disasters such as earthquake could seriously damage most buildings especially those with insufficient resistance located in urban worn-out textures. In order to reduce unpleasant consequences of an earthquake, appropriate policies need to be considered to persuade the beneficiaries to follow retrofitting standards in the process of planning, designing, and construction of buildings. These policies shall be implemented through institutions in arbitrary or obligatory forms, by encouragement or penalty mechanisms. In order to consider these policies, first of all we need to identify the beneficiaries and their particulars. By studying and considering subjects discussed in...
Upgrading the Existing Methods for Seismic Evaluation of Soil-Structure Systems with Embedded Foundation
,
Ph.D. Dissertation
Sharif University of Technology
;
Ghannad, Mohammad Ali
(Supervisor)
Abstract
Base flexibility of structures, cause changes in seismic input motions to the structure, and hence, result in variations in structural seismic responses. This phenomenon is commonly referred to as soil-structure interaction (SSI). The effect of base flexibility on seismic responses is usually investigated from two main aspects: 1) Kinematic interaction (KI) , 2) Inertial Interaction (II). KI effects are induced, first, because of the stiffness contrast between the foundation and the flexible base, and second, because of phase difference of the receiving waves in the contact boundary between the foundation and the flexible base. These effects may results in variations in frequency content of...
Nonlinear seismic assessment of steel moment frames using time-history, incremental dynamic, and endurance time analysis methods
, Article Scientia Iranica ; Volume 20, Issue 3 , 2013 , Pages 431-444 ; 10263098 (ISSN) ; Zarringhalam, Y ; Estekanchi, H. E ; Yahyai, M ; Sharif University of Technology
2013
Abstract
A recent method in the seismic assessment of structures is Endurance Time Analysis (ETA). ETA is a time-history-based dynamic pushover procedure, in which structures are subjected to gradually intensifying acceleration functions called Endurance Time Acceleration Functions (ETAFs), and their performances are evaluated based on the equivalent intensity level that they can endure while satisfying required performance goals. In this paper, the accuracy of the ETA in the seismic assessment of steel moment resisting frames is compared with the Time History Analysis (THA) and Incremental Dynamic Analysis (IDA) methods. For this purpose, a set of mid-rise and high-rise frames were selected as a...
Seismic assessment of unanchored steel storage tanks by endurance time method
, Article Earthquake Engineering and Engineering Vibration ; Volume 10, Issue 4 , 2011 , Pages 591-603 ; 16713664 (ISSN) ; Estekanchi, H. E ; Sharif University of Technology
Abstract
Liquid storage tanks are essential structures that are often located in residential and industrial areas; thus an assessment of their seismic performance is an important engineering issue. In this paper, the seismic response of unanchored steel liquid storage tanks is investigated using the endurance time (ET) dynamic analysis procedure and compared to responses obtained for anchored tanks under actual ground motions and intensifying ET records. In most cases, the results from ground motions are properly obtained with negligible differences using ET records. It is observed that uplifting of the tank base, which is closely related to the tank aspect ratio, has the greatest significance in the...
Application of Endurance Time Method in Seismic Evaluation of Existing Steel Buildings
,
M.Sc. Thesis
Sharif University of Technology
;
Esmaeil Pourestekanchi, Homayun
(Supervisor)
Abstract
This study has been carried out for investigating the need for an appropriate and fast seismic analysis method to be applied in performance based design (PBD), and show the application of Endurance Time (ET) method and it’s advantages in PBD. Necessary theories were generated in hazard analysis, bi-directional seismic analysis, introduction of dynamic push-over curve and application. As a secondary goal, potential of this method in more complicated nonlinear domains is assessed. Application of ET and its advantages in PBD is shown with an example of SMF, NDCBF, CBF and BRBF building after modeling nonlinear interactional behavior of beams and columns, and also modeling buckling and...
Reliability and Probabilistic Seismic Assessment of Fixed Jacket Type Offshore Platforms
,
M.Sc. Thesis
Sharif University of Technology
;
Golafshani, Ali Akbar
(Supervisor)
Abstract
This thesis encompasses a number of issues in earthquake engineering which may appear quite diverse in nature. Several methodological aspects of both conventional and novel approaches to probabilistic seismic hazard assessment are discussed here along with subjects more strictly pertinent to structural and geotechnical engineering. This work, however, has a unique, ultimate goal: to provide procedures for an effective and practical probabilistic estimation of structural demand of offshore platforms due to seismic ground shaking. In modern multi-level design and rehabilitation procedures, structural performance is in fact quantified by deformation demand levels exceeded with a specified...
Comparative Study of Life Cycle Cost of Steel and Concrete Building Systems Designed Based on Standard 2800 by Endurance Time Method
, M.Sc. Thesis Sharif University of Technology ; Esmaeil Pourestekanchi, 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. The aim of this research is Comparative study of life cycle cost of steel and concrete building systems designed based on standard 2800 by Endurance Time Method. These costs include initial cost and life cycle cost Due to the aftermath of the earthquake in the life of the structure. In this research, because it requires a lot nonlinear dynamic time history analysis, Endurance Time Method used which is both good accuracy and also drastically reduces the cost of computing-off. Selected models for the study, four,...
Performance Evaluation of Diaphragms in Tub Girder Superstructures
, Ph.D. Dissertation Sharif University of Technology ; Maleki, Shervin (Supervisor)
Abstract
In recent years, steel tub girder superstructures have been exceedingly used in long span superstructures due to their significant torsional and flexural stiffnesses. In such superstructures, end diaphragms made of plates are one of the most important members in transferring seismic forces to the substructure. Despite the importance of end diaphragms, limited number of studies have been conducted on their behaviour and as a result, their design procedure is not clear. In this dissertation, different configurations of end diaphragms in elastic steel tub girder superstructures were evaluated using finite element models and the required equations for stiffness and strength were derived....
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...
Application of Damage Indices In Seismic Analysis of Concrete Frames Using Endurance Time Method
, M.Sc. Thesis Sharif University of Technology ; Esmaeil Pourestekanchi, Homayoun (Supervisor)
Abstract
In most places in the world as it is in our country, structural vibration caused by earthquakes are among the most destructive menaces for the building. For this reason one of the main goals for civil engineers is constructing structures that can perform properly in an earthquake-exposed situation. For moving toward this goal it is necessary to estimate structural responses considering probable earthquake excitation and use these data for design of new structures or retrofitting of existing ones. In this research, the capability of a new method named Endurance Time analysis in seismic assessment of concrete moment frame is investigated in nonlinear range. ET is a new dynamic time history...
A parametric study of seismic response in anchored steel tanks with endurance time method
, Article Scientia Iranica ; Vol. 21, Issue. 5 , 2014 , pp. 1608-1619 ; ISSN: 10263098 ; Estekanchi, H. E ; Vafai, A ; Sharif University of Technology
Abstract
In this paper, the seismic response of anchored cylindrical steel tanks with various dimensional parameters has been investigated by endurance time method considering fluid-structure interaction effects. Various response quantities, such as stresses and displacements, have been evaluated by subjecting tanks to specially designed intensifying accelerograms and their performance is judged based on their response at predefined level(s) of dynamic excitation. It is shown that ET analysis can reliably predict the result of ground motion time history analysis in all seven tank models studied. In four of the tanks in which height of the shell and the level of fluid is the same, the variation of...
Damage estimation of steel moment-resisting frames by endurance time method using damage-based target time
, Article Journal of Earthquake Engineering ; 2017 , Pages 1-30 ; 13632469 (ISSN) ; Estekanchi, H. E ; Sharif University of Technology
Taylor and Francis Ltd
2017
Abstract
In endurance time method, seismic performance of structures under artificial intensifying accelerograms is investigated. In this method, the time duration of excitation (target time) will be assigned on the basis of linear response spectra. Damage spectra, which are the variation of a damage index versus the system period, can be used effectively to modify the target time of the excitations. In this research, various damage indices for a number of steel moment frames are estimated using the endurance time method with two types of target time, and the results are compared with those corresponding to the scaled real earthquakes. It is observed that damage estimation of the frames via the...
Damage estimation of steel moment-resisting frames by endurance time method using damage-based target time
, Article Journal of Earthquake Engineering ; Volume 22, Issue 10 , 2018 , Pages 1806-1835 ; 13632469 (ISSN) ; Estekanchi, H. E ; Sharif University of Technology
Taylor and Francis Ltd
2018
Abstract
In endurance time method, seismic performance of structures under artificial intensifying accelerograms is investigated. In this method, the time duration of excitation (target time) will be assigned on the basis of linear response spectra. Damage spectra, which are the variation of a damage index versus the system period, can be used effectively to modify the target time of the excitations. In this research, various damage indices for a number of steel moment frames are estimated using the endurance time method with two types of target time, and the results are compared with those corresponding to the scaled real earthquakes. It is observed that damage estimation of the frames via the...
Nonlinear Quantification and Seismic Evaluation of EBF Disposal Systems in Mid-story Structures
, M.Sc. Thesis Sharif University of Technology ; Mofid, Masoud (Supervisor)
Abstract
In the present study it was intended to evaluate the seismic performance of multi-story EBF structures for designing. When adopting this method, parametric studies are carried out based on the nonlinear performance of such systems whiting the framework of nonlinear static and dynamic analyses. In lines with seismic strengthening of such structures, this study tries to reassess the performance of these systems through increasing ductility and replacing bracing frames with energy damper and special seismic systems. As a result, a fuse type performance is created to protect the other elements of the structure. This study describes the seismic strengthening of this type of dampers using simple...