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shekarchi--ashkan
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Experimental Study on Flexural and Shear Behavior of Steel Beams Using Carbon Laminate
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
There is a requirement for strengthening of steel structures due to undesirable design, wrong implementation, bad maintenance and changes in design codes. Many studies have been done on strengthening of concrete specimens but there is a need for reinforcement of steel specimens yet. In the present paper, results of an experimental study on strengthening and reinforcing of steel beams under mechanical loads have been presented. Totally, Sixteen steel specimens with span’s lengths of 0.2, 0.5 and 1 meter were reinforced by carbon laminates and subjected to -point bending load. Three failure modes of shear yielding, flexural yielding and lateral_torsional buckling in the beams were examined....
Sustainable-Resilient Supplier Selection Through Fuzzy Multi-Criteria Decision Making Approaches
, M.Sc. Thesis Sharif University of Technology ; Akbari Jokar, Mohammad Resa (Supervisor) ; Memari, Ashkan (Co-Supervisor)
Abstract
Today, with the expansion of business relations at international levels, there are many organizations that operate in global supply chains. Activities at such levels face new types of challenges in various fields of "supply chain management" pillars, of which "supplier selection" is one of them. The possibility of unexpected events, the need to comply with environmental protection laws, as well as the need to take into account social considerations, are among the things that have increased by being in larger supply chains, making it challenging to provide the basic resources needed in such chains and forcing their managers to considering considerations other than what they have always...
Cost and Profit Efficiency of Iranian Banking Sector Using Parametric and Non-Parametric Methods
, M.Sc. Thesis Sharif University of Technology ; Keshavarz Haddad, Gholamreza (Supervisor)
Abstract
In this research, by employing DEA non-parametric and SFA parametric methods, the cost and profit efficiency of Iranian banking system are estimated in the period 2002-2007. Afterwards, the results are evaluated and analyzed via six aspects proposed in consistency conditions. Furthermore, we take advantage of standard non-frontier performance measures namely the cost to assets ratio (TC/A) and profit to assets (/A) for comparing them with estimated cost and profit efficiencies. The findings suggest the high degree of consistency between the results of parametric and non-parametric methods; meanwhile, any significant correlation is not seen between ownership (public/private) and type of...
Effect of seawater on pull-out behavior of glued-in single rods set parallel to the grain of timber joints
, Article Construction and Building Materials ; Volume 222 , 2019 , Pages 342-357 ; 09500618 (ISSN) ; Majdabadi Farahani, E ; Vatani Oskouei, A ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
This paper experimentally investigates the effects of seawater on pull-out behavior of single rods glued in timber parallel to grain. Considering different rod diameters (6, 8, 10 mm), slenderness ratios (7.5, 10, 15), rebar materials (steel and GFRP), and immersion time in seawater (0, 10, 20, 30, 60, 90 days), 324 specimens were tested. Mean strength reduction about 39 and 55 percent was observed for 90-day immersed joints constructed with GFRP and steel rebars, respectively. Rebar diameter and slenderness ratio significantly influenced ultimate loads, and dominant failure mode was at adhesive/timber interface. Finally, two novel strength models were developed empirically. © 2019 Elsevier...
Experimental investigation on the behavior of RC arches strengthened by GFRP composites
, Article Construction and Building Materials ; Volume 235 , 28 February , 2020 ; Moradi, H ; Kazemian, A ; Shekarchi, M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
An experimental investigation on the behavior of RC arches strengthened by glass fiber-reinforced polymer (GFRP) composites is presented. Twelve samples were tested in order to determine influence of arrangement and number of GFRP layers on RC arches having different steel reinforcement ratios. The arches were tested under centrally concentrated point load using displacement control condition. Load-deflection behavior, failure mode, GFRP debonding, angle between hinge formation and supports and crack propagation pattern are studied extensively. Based on test results, extrados strengthening is much more effective than intrados strengthening in increasing ultimate load carrying capacity which...
Flexural behavior of timber beams strengthened with pultruded glass fiber reinforced polymer profiles
, Article Composite Structures ; Volume 241 , 2020 ; Vatani Oskouei, A ; Raftery, G. M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Timber is one of the materials widely used in construction and industry all over the world. In this paper, the behavior of strengthened timber beams made of beech wood (Fagus orientalis) were investigated experimentally. The composite timber beams were reinforced with flat, U-shaped, and L-shaped pultruded Glass Fiber Reinforced Polymer (GFRP) profiles. The GFRPs were attached to tensile or both tensile and compressive surfaces of beams. Altogether, 24 specimens, including 20 strengthened beams and 4 un-strengthened (control) beams, were tested under three-point bending test. Flexural behavior of specimens was evaluated through their load versus mid-span displacement curves, ultimate load...
Performance of glued-in rod timber joints under seawater and UV exposure cycles
, Article Construction and Building Materials ; Volume 322 , 2022 ; 09500618 (ISSN) ; Shakiba, M ; Yekrangnia, M ; Tannert, T ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Timber joints with glued-in rod connections provide an interesting technical solution for numerous structural applications, also under harsh environmental conditions; yet little research is available on this topic. This paper experimentally investigated the effect of exposure to seawater wetting/drying cycles and seawater wetting/drying plus UV radiation cycles on the pull-out performance of glued-in rod timber connections. Three rod diameters, three anchorage lengths, and four exposures were considered, leading to manufacturing and testing a total of 189 specimens. The quasi-static monotonic pull-out resistance of joints was a function of rod diameter and anchorage length as well as...
Effect of utilizing glass fiber-reinforced polymer on exural strengthening of rc arches
, Article Scientia Iranica ; Volume 26, Issue 4A , 2019 , Pages 2299-2309 ; 10263098 (ISSN) ; Khaloo, A. R ; Shekarchi, M ; Kazemian, A ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
An experimental study of the. flexural behavior of Reinforced-Concrete (RC) arches strengthened with Glass Fiber-Reinforced Polymer (GFRP) layers was performed. A total of 36 specimens including 3 un-strengthenod (control) and 33 strengthened RC arches were tested under centrally concentrated point load. The variables of this study were steel reinforcement ratio, number of GFRP layers, and location and arrangement of GFRP layers. Failure mode, load-displacement response of specimens, crack propagation patterns, and GFRP debonding were examined. The extrados strengthening method was shown to Ix1 more effective than the intrados strengthening one in improving the failure load and rigidity of...
Effect of utilizing glass fiber-reinforced polymer on exural strengthening of rc arches
, Article Scientia Iranica ; Volume 26, Issue 4A , 2019 , Pages 2299-2309 ; 10263098 (ISSN) ; Khaloo, A. R ; Shekarchi, M ; Kazemian, A ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
An experimental study of the. flexural behavior of Reinforced-Concrete (RC) arches strengthened with Glass Fiber-Reinforced Polymer (GFRP) layers was performed. A total of 36 specimens including 3 un-strengthenod (control) and 33 strengthened RC arches were tested under centrally concentrated point load. The variables of this study were steel reinforcement ratio, number of GFRP layers, and location and arrangement of GFRP layers. Failure mode, load-displacement response of specimens, crack propagation patterns, and GFRP debonding were examined. The extrados strengthening method was shown to Ix1 more effective than the intrados strengthening one in improving the failure load and rigidity of...
Mechanical strength of CFRP and GFRP composites filled with APP fire retardant powder exposed to elevated temperature
, Article Fire Safety Journal ; Volume 115 , 2020 ; Majdabadi Farahani, E ; Yekrangnia, M ; Ozbakkaloglu, T ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Ammonium polyphosphate (APP) is one of the most widely used halogen-free flame retardant, added in various resins to improve the fire properties, such as flame and smoke spread ratings and LOI, of fiber-reinforced polymer (FRP) composites. This paper experimentally investigates the effects of using APP, as a fire-retardant filler, on mechanical properties (i.e. ultimate tensile, flexural, and bond strength) of glass fiber-reinforced polymer (GFRP) and carbon fiber-reinforced polymer (CFRP) composites. Based on two fiber types (i.e. carbon and glass) and three different APP mass fractions in resin (i.e. 0, 20, and 40% of total weight of matrix), six sets of specimens were prepared for each...
Effect of elevated temperatures on the compressive behavior of timber filled steel and pultruded GFRP tubes
, Article Composite Structures ; Volume 271 , 2021 ; 02638223 (ISSN) ; Yekrangnia, M ; Biniaz, A ; Raftery, G. M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
This study examines the use of timber as a filler material for steel and pultruded GFRP tube elements and the performance of these sections is compared to solid timber columns, hollow steel and hollow pultruded GFRP tube element after exposure to elevated temperature. In total, 102 specimens were fabricated and exposure to elevated temperature ranging from 20 to 700 °C was evaluated. It was found out that filled tubes using timber could improve the compressive strength and stiffness of tubular section specimens up to 73 and 212 percent, respectively. Timber filled steel tube (TFST) and hollow steel tube specimens had a better performance at elevated temperature in comparison to other...
Concrete basic creep predi ction based on time-temperature equivalence relation and short-term tests
, Article Arabian Journal for Science and Engineering ; Volume 35, Issue 2 A , 2010 , Pages 105-121 ; 13198025 (ISSN) ; Mostofinejaad, D ; Saadatpour, M. M ; Shekarchi, M ; Sharif University of Technology
2010
Abstract
Using temperature as an accelerator of reactions in short-term tests for the prediction of concrete creep is the main idea of this paper. The application of a time-temperature equivalence relation is examined with reference to creep in concrete under constant moisture conditions. A mathematical model is developed which uses short-term tests to predict long-term creep deformation of concrete under constant moisture conditions, taking into account aging of concrete and the influence of temperature. The thermal activation is assumed to be governed by the Arrhenius principle, and the activation energy of the viscosity of water is found to be applicable in the analysis of the experimental data....
Effects of short term and long term Extremely Low Frequency Magnetic Field on depressive disorder in mice: Involvement of nitric oxide pathway
, Article Life Sciences ; Volume 146 , 2016 , Pages 52-57 ; 00243205 (ISSN) ; Farzam Pour, S ; Sadr, A ; Shekarchi, B ; Majid Zadeh, A. K ; Sharif University of Technology
Elsevier Inc
2016
Abstract
Aims Previous reports on the possible effects of Extremely Low Frequency Magnetic Fields (ELF MF) on mood have been paradoxical in different settings while no study has yet been conducted on animal behavior. In addition, it was shown that ELF MF exposure makes an increase in brain nitric oxide level. Therefore, in the current study, we aimed to assess the possible effect(s) of ELF MF exposure on mice Forced Swimming Test (FST) and evaluate the probable role of the increased level of nitric oxide in the observed behavior. Main methods Male adult mice NMRI were recruited to investigate the short term and long term ELF MF exposure (0.5 mT and 50 Hz, single 2 h and 2 weeks 2 h a day). Locomotor...
Activated carbon/metal-organic framework nanocomposite: Preparation and photocatalytic dye degradation mathematical modeling from wastewater by least squares support vector machine
, Article Journal of Environmental Management ; Volume 233 , 2019 , Pages 660-672 ; 03014797 (ISSN) ; Abdi, J ; Taghizadeh, M ; Taghizadeh, A ; Hayati, B ; Shekarchi, A. A ; Vossoughi, M ; Sharif University of Technology
Academic Press
2019
Abstract
Herein, Kiwi peel activated carbon (AC), Materials Institute Lavoisier (MIL-88B (Fe), and AC/MIL-88B (Fe) composite were synthesized and used as catalysts to degrade Reactive Red 198. The material properties were analyzed by the FTIR, BET-BJH, XRD, FESEM, EDX, TGA, and UV–Vis/DRS. The BET surface area of AC, MIL-88B (Fe) and AC/MIL-88B (Fe) was 1113.3, 150.7, and 199.4 m2/g, respectively. The band gap values (Eg) estimated by Tauc plot method, were obtained 5.06, 4.19 and 3.79 eV for AC, MIL-88B (Fe) and AC/MIL-88B (Fe), respectively. The results indicated that the AC/MIL-88B (Fe) composite had higher photocatalytic activity (99%) than that of pure AC (79%) and MIL-88B (Fe) catalysts (87%)....