The Effect of Earthquake Vertical Component on Nonlinear Analysis of Concrete Gravity Dams Using Endurance Time Method

, M.Sc. Thesis Sharif University of Technology Zarei, Mehdi (Author) ; 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...

Collapse Analysis of Steel Moment Frames Using Endurance Time Method

, M.Sc. Thesis Sharif University of Technology Ehsan Rahimi (Author) ; 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...

Application of Endurance Time Method in Performance-based Design

, M.Sc. Thesis Sharif University of Technology Mirzaee, Amin (Author) ; 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...

Evaluation of Seismic Behavior of Anchored and Unanchored Tanks By Using Endurance Time Method

, M.Sc. Thesis Sharif University of Technology Alembagheri, Mohammad (Author) ; 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)...

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 Eslami Farkoosh, Ehsan (Author) ; 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...

Endurance time method: Exercise test applied to structures

, Article Asian Journal of Civil Engineering ; Volume 10, Issue 5 , 2009 , Pages 559-577 ; 15630854 (ISSN) Esmaeilpour Estekanchi, H ; 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...

Design & Analyze of Spherical Shell & Pointed Domes by Endurance Time Method

, M.Sc. Thesis Sharif University of Technology Akbarzadeh Chiniforush, Alireza (Author) ; 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...

Experimental and analytical study of block slit damper

, Article Journal of Constructional Steel Research ; Volume 141 , February , 2018 , Pages 167-178 ; 0143974X (ISSN) Ahmadie Amiri, H ; 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) Mashayekhi, M. R ; 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...

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) Pournamazian Najafabad, E ; 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...

Microstructure, mechanical properties, corrosion behavior and cytotoxicity of Mg-Zn-Al-Ca alloys as biodegradable materials

, Article Journal of Alloys and Compounds ; Vol. 607 , 2014 , Pages 1-10 ; ISSN: 09258388 Homayun, B ; Afshar, A ; Sharif University of Technology

2014

Abstract

Recently, considerable attentions have been paid to alloy Mg-4Zn-0.2Ca for biomedical applications due to its suitable biocompatibility and acceptable mechanical properties. In this work, the effects of the addition of different amounts of Al on microstructure, mechanical properties, degradation behavior, and biocompatibility of this alloy were investigated. The corrosion behaviors of the alloys were investigated through polarization tests, chronoamperometry analysis, immersion tests, and EIS experiments. The mechanical properties were analyzed by using tensile tests and compression tests. The results showed that the addition of Al up to 3 wt.% considerably modifies the degradation behaviors...

Surveying The Biodegradation Behavior, Biocompatibility and Mechanical Properties of Mg-4Zn-xAl-0.2Ca Alloys

, M.Sc. Thesis Sharif University of Technology Homayun, Bahman (Author) ; Afshar, Abdollah (Supervisor)

Abstract

Due to their favorable biodegradability, Magnesium and its alloys have always attracted such a lot of research interests for making temporary implants. With the same direction, Mg-4Zn-0.2Ca has recently absorbed lots of research interests, due to its excellent biocompatibility. As the most regarded draw back concerned with this alloy, poor corrosion resistance is frequently discussed. Accordingly, in the present work it has been tried to come over this problem by addition different amount of aluminum, including 1, 3, 5, 7.5, and 10 percent, to this alloy; without causing any negative effect on its biocompatibility, and to present a new alloy composition with modified degradation behavior....

A comprehensive evaluation between the efficiency of different treatments in modifying the properties and behavior of magnesium alloys as degradable biomaterials

, Article Materials and Corrosion ; Volume 68, Issue 9 , 2017 , Pages 995-1003 ; 09475117 (ISSN) Homayun, B ; Afshar, A ; Sharif University of Technology

2017

Abstract

The addition of alloying elements to magnesium leads to microstructural refinement and improves its properties. However, this strategy is accompanied by another concurrent phenomenon − that is − intergranular segregation and the formation of secondary phases in grain boundaries, deteriorating the properties. In this work, the efficacy of two main factors on modifying the mechanical properties and corrosion behavior of Mg-4Zn-1Al-0.2Ca alloy was investigated separately: 1) dissolution of secondary phases; and 2) grain refinement. Based on the results, heat treatment of the as-cast alloy can increase the UTS from 174.4 to 213.2 MPa, decrease the corrosion current density from 81 to 49 μA/cm2,...

Stress Analysis of LCP and DCP in Normal and Osteoporosis Femur

, M.Sc. Thesis Sharif University of Technology Esmaeilpour, Mohammad Rasoul (Author) ; Firoozbakhsh, Keikhosrow (Supervisor)

Abstract

Metallic implants are often used in the open reduction and internal fixation of fractures. Open reduction and internal fixation are commonly used in cases of trauma when the bone cannot be healed using external methods such as casting. The locking compression plate combines the conventional screw holes, which use non-locking screws, with locking screw holes, which use locking head screws. This allows for more versatility in the application of the plate.
In the present work, the stress (von-mises) and deformation of a locking compression plate fixed across a transverse fracture (2-mm gap) at the midshaft of femur was evaluated by Ansys software. Femur model is divided to two part...

Mechanical Behavior Analysis of Biological Cells Using an Electrostatically Actuated Microbeam

, M.Sc. Thesis Sharif University of Technology Esmaeilpour Charandabi, Sina (Author) ; Firoozbakhsh, Keikhosrow (Supervisor)

Abstract

Researches in last decades have shown that biological cell’s functionality is related to the way of their deformation in response to forces and stresses exerted on the cell. Therefore designing microsensors with easy and economical applicationswhich are capable for determining cell mechanical properties seems to be logical. In this project using an electrostatically actuated microbeam with both clamped ends equipped with an indenter at midpoint to transmit force on the cell, proposed as a technique to apply axial load on the cell. Inthis research by implementation of approximated methods for solving nonlinear algebraic and differential equations, governing on microbeam deflection, it has...

The Equivalent Period and Damping of Soil-Structure Systems on Layered Half-Space

, M.Sc. Thesis Sharif University of Technology Esmaeilpour, Pouria (Author) ; Ghannad, Mohammad Ali (Supervisor)

Abstract

Since the early 1980s, it is well-known that the dynamic properties of structures are effected by flexibility of the underlying soil due to Soil-Structure Interaction (SSI). As a result, the soil-structure systems usually has a longer natural period and higher damping ratio that structure would have in the fixed-base state. The importance of SSI effect as well as the complexity of the phenomenon have made it the subject of several researches for the last four decades. It also has found its way into some seismic codes and provisions as simplified guidelines.In the present paper, a simplified 3DOF model is suggested as the soil-structure system by replacing the structure by a SDOF model using...

Synthesis and characterization of mixed–metal oxide nanoparticles (cenio3, cezro4, cecao3) and application in adsorption and catalytic oxidation–decomposition of asphaltenes with different chemical structures

, Article Petroleum Chemistry ; Volume 60, Issue 7 , 2020 , Pages 731-743 Dehghani, F ; Ayatollahi, S ; Bahadorikhalili, S ; Esmaeilpour, M ; Sharif University of Technology

Pleiades Publishing 2020

Abstract

Abstract: This study investigates the catalytic activity of mixed–metal oxide nanoparticles with different surface acidities on asphaltene adsorption followed by catalytic oxidation–decomposition. Three different types of mixed–metal oxide nanoparticles (CeNiO3, CeCaO3 and CeZrO4) were synthesized, and their size, structure, and acid properties were characterized by field–emission scanning electron microscopy (FE–SEM), energy-dispersive X-ray spectroscopy (EDX), the high–resolution transmission electron microscopy (HR-TEM), X-ray powder diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area measurement and ammonia temperature-programmed desorption (NH3–TPD). Asphaltenes were extracted...

Multi-Directional Seismic Analysis and using ET Method in Estimation of the Results

, M.Sc. Thesis Sharif University of Technology Asgarieh, Eliyar (Author) ; Esmaeil Pourestekanchi, Homayun (Supervisor)

Abstract

Exact and safe structural analysis and design under various loadings is an important issue, which have engaged engineers for a long time. Till now, building design codes have suggested three main methods for seismic analysis of structures, which consist of: Static analysis, Pseudo-dynamic response spectrum analysis and Time history analysis. The first two methods are too approximate, especially in irregular structures which demand exact 3d analyses. The most reliable method is Time history method. With advance of computational tools, engineers tend toward using more reliable analysis methods and using old fashioned rough methods is becoming less popular. One of the issues, which is important...

Investigation of Endurance Time Method in Seismic Analysis of Vertically Irregular Elastic Steel Frames

, M.Sc. Thesis Sharif University of Technology Ahmadi, Mehdi (Author) ; Esmaeil Pourestekanchi, Homayun (Supervisor)

Abstract

Recent studies show that irregular structures have been damaged more than regular ones during earthquakes. This proves importance of seismic response determination of this type of structures. Today, Codes define irregularity in structures and restrict seismic analysis and design of these types of structures. The Endurance Time (ET) method is a time-history based dynamic pushover procedure for seismic analysis and design of structures that has been recently proposed in Sharif University. This thesis illustrates ET capability in analysis and design of vertically irregular frames. Irregular frames with three, seven and twelve story high were designed with two types of mass and stiffness...

Application of Endurance Time Method in Seismic Analysis of Bridges

, M.Sc. Thesis Sharif University of Technology Ghaffari, Esmaeil (Author) ; Esmaeil Pourestekanchi, Homayun (Supervisor)

Abstract

In this research the appilication of a new method named Endurance Time (ET) analysis in seismic analysis of multi span bridges in linear and nonlinear ranges is investigated. Endurance Time is a time history based method of seismic analysis. In this method structure is subjected to an intensifying predefined acceleration function and different damage indices of the structure are evaluated through analysis time. The Endurance Time criterion and the Endurance Time acceleration functions have been generated in previous researchs of ET group. Using 7 earthquake records which are selected from hundred ones of PEER database based on FEMA p695 recommendations, several scaling methods are used to...