Loading...
Search for: elevated-temperature
0.006 seconds
Total 65 records

    Tensile properties of GFRP laminates after exposure to elevated temperatures: Effect of fiber configuration, sample thickness, and time of exposure

    , Article Composite Structures ; Volume 238 , 2020 Ashrafi, H ; Bazli, M ; Jafari, A ; Ozbakkaloglu, T ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    This study investigates the tensile properties of various GFRP laminates after exposure to elevated temperatures. Fiber configuration, exposure temperature and laminate thickness were considered as the test variables. A total number of 180 specimens were tested in tension to obtain the mechanical properties of GFRP laminates. Alongside the mechanical tests, SEM analyses were conducted on selected samples before testing to investigate the resin, fiber, and their interface damages. Regardless of the sample type, it was generally observed that the reduction rate in the tensile strength increased with an increase in the exposure time and a decrease in the laminates’ thickness. The results of... 

    Effect of elevated temperatures on the compressive behavior of timber filled steel and pultruded GFRP tubes

    , Article Composite Structures ; Volume 271 , 2021 ; 02638223 (ISSN) Shekarchi, M ; 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... 

    Behaviour of End-Plate Connections in 3D Frames Under Fire Conditions: Experimental Study

    , Article International Journal of Steel Structures ; Volume 18, Issue 3 , 2018 , Pages 734-749 ; 15982351 (ISSN) Khonsari, S.V ; Vosough Grayli, P ; Ghorbani, A ; Roshani Moghaddam, A ; Sharif University of Technology
    Korean Society of Steel Construction  2018
    Abstract
    Due to high vulnerability of steel structures to elevated temperatures and the need for taking adequate and effective measures to reduce human and financial losses in fires, a thorough understanding of such behaviour is of utmost importance. In this research, a half-scale 3D model, comprising moment-resisting frames, equipped with flush end-plate connections, in one direction, and braced frames in the other, was subjected to a scaled ISO 834 standard fire. The maximum attained temperature was 1055 °C. The results showed that the structure tolerates high temperatures for an appreciable amount of time before collapsing. Moreover, for thick flush end-plates, which were used in this study, the... 

    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... 

    The effect of elevated temperatures on the compressive section capacity of pultruded GFRP profiles

    , Article Construction and Building Materials ; Volume 249 , July , 2020 Khaneghahi, M. H ; Najafabadi, E. P ; Bazli, M ; Vatani Oskouei, A ; Zhao, X. L ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    The compressive performance of glass fiber reinforced polymer (GFRP) profiles subjected to elevated temperature was investigated through a large number of (3 0 0) tests. The effects of profile cross-sectional area, slenderness, and temperature on the behavior of the GFRP profiles at temperatures ranging from 25 to 400 °C were determined. It was observed that the compressive strength of the GFRP profiles has been decreased by half as the temperature exceeded 90 °C, i.e., close to the glass transition temperature of the matrix. The temperature and ratio of cross-sectional area to external perimeter were determined as two major parameters affecting section capacity. © 2020 Elsevier Ltd  

    Corrigendum: “geopolymers vs. alkali-activated materials (AAMs): a comparative study on durability, microstructure, and resistance to elevated temperatures of lightweight mortars” (JCBM 222 (2019) (49–63), (S0950061819315089), (10.1016/j.conbuildmat.2019.06.079))

    , Article Construction and Building Materials ; Volume 283 , 2021 ; 09500618 (ISSN) Ameri, F ; Shoaei, P ; Zareei, A. R ; Behforouz, B ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    The authors regret that there was an error in the XRD pattern for pumice shown in Fig. 8. The authors have re-analyzed the pumice to address the concerns over the reliability of the pattern due to the presence of noises, and the updated XRD pattern has been shown in Fig. 8 here for more accuracy of the presented information. It is noteworthy that this change does not affect any of the conclusions. The authors would like to apologise for any inconvenience caused. © 2021 Elsevier Ltd  

    The Performance in Temperature Increas of Bolted Slant Endplate Connection

    , M.Sc. Thesis Sharif University of Technology Zahmatkesh, Farshad (Author) ; Kazemi, Mohammad Taghi (Supervisor)
    Abstract
    The main goal of this research is to evaluate the vertical and slant bolted endplate connections performance in steel moment frame structures under thermal effect in elastic range for two cases. In the first case, frictionless and in the second case slips with friction are considered. By finite element analysis, the connections are simulated to study the performance and verify simplified models of vertical and slant bolted endplate connections due to increase in temperature. The results of a vertical bolted endplate connection and a slant bolted endplate connection due to increase in temperature are compared the effect of slope of end plate reduction of axial force on beam is investigated.... 

    Post-fire Behavior Evaluation of Slag-Based Geopolymer Concrete

    , M.Sc. Thesis Sharif University of Technology Palizi, Soheil (Author) ; Toufigh, Vahab (Supervisor)
    Abstract
    Concrete, a versatile construction material, combines cement, aggregates, and water to form a composite known for its durability and adaptability in various architectural and engineering applications. Its widespread use stems from its ability to efficiently bear heavy loads while maintaining longevity. However, producing concrete's key ingredient, cement, contributes significantly to environmental harm by emitting substantial carbon dioxide during its manufacturing process. This carbon footprint underscores the urgent need for sustainable alternatives and innovative practices in the construction industry to mitigate the detrimental effects on our planet. On the other hand, understanding the... 

    Physico-mechanical properties and micromorphology of AAS mortars containing copper slag as fine aggregate at elevated temperature

    , Article Journal of Building Engineering ; Volume 39 , 2021 ; 23527102 (ISSN) Ameri, F ; Shoaei, P ; Zahedi, M ; Karimzadeh, M ; Musaeei, H. R ; Cheah, C. B ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    Copper slag (CS) is an industrial by-product, which is commonly disposed in engineered landfills. Prior studies have successfully incorporated CS as an aggregate phase in cementitious materials. However, the alkali-activated material (AAM) incorporating CS has been scarcely studied. Specifically, the elevated temperature behavior of AAM with CS has not been investigated previously. The present paper aims to study the effects of elevated temperature treatment on the mass loss and residual strength of alkali-activated slag mortars incorporating 0–100% (by volume) of CS with an incremental step of 20% instead of natural sand. The mass loss, compressive and flexural strengths, and microstructure... 

    The effect of elevated temperatures on the tensile performance of GFRP and CFRP sheets

    , Article Construction and Building Materials ; Volume 190 , 2018 , Pages 38-52 ; 09500618 (ISSN) Jarrah, M ; Pournamazian Najafabadi, E ; Houshmand Khaneghahi, M ; Vatani Oskouei, A ; Sharif University of Technology
    Elsevier Ltd  2018
    Abstract
    In this study, the effects of fiber type (i.e., carbon and glass fibers) and intumescent paint on the tensile performance of fiber reinforced polymer (FRP) sheets at elevated temperatures are investigated. For this purpose, a series of tensile tests were conducted on the glass and carbon fiber reinforced polymer (GFRP and CFRP) sheets, with and without intumescent fire retardant paint, at different elevated temperatures. The studied temperatures ranged from 25 °C to 600 °C. Scanning electron microscopy was also used to examine the effects of elevated temperatures on FRP sheets and the fire protecting mechanism of the intumescent paint. Based on the test results, the tensile strength of the... 

    Geopolymers vs. alkali-activated materials (AAMs): A comparative study on durability, microstructure, and resistance to elevated temperatures of lightweight mortars

    , Article Construction and Building Materials ; Volume 222 , 2019 , Pages 49-63 ; 09500618 (ISSN) Ameri, F ; Shoaei, P ; Zareei, S. A ; Behforouz, B ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    This paper studied the durability, microstructure, and fire behavior of lightweight mortars based on cement, metakaolin (MK), ultrafine ground granulated blast furnace slag (UGGBFS), ceramic waste powder (CWP), and clay brick waste powder (CBWP). Two sets of mixes were prepared with two types of lightweight aggregate including lightweight expanded clay aggregate (LECA) and pumice aggregate. Regarding the durability assessment, the electrical resistivity and water absorption of the mortars were measured. The UGGBFS-based alkali-activated mortar with pumice aggregate exhibited the highest electrical resistivity and lowest water absorption, while CBWP-based geopolymer mortar with LECA showed... 

    The tensile performance of FRP bars embedded in concrete under elevated temperatures

    , Article Construction and Building Materials ; Volume 211 , 2019 , Pages 1138-1152 ; 09500618 (ISSN) Pournamazian Najafabadi, E ; Vatani Oskouei, A ; Khaneghahi, M. H ; Shoaei, P ; Ozbakkaloglu, T ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    In this research, the mechanical properties of glass and carbon fiber reinforced polymer (FRP) bars with epoxy resin matrices embedded in concrete were investigated under an extensive range of elevated temperatures (i.e., 25–800 °C). Embedded FRP bars with various bar diameters were studied in order to determine bar diameter influence on the results. In addition, analysis of variance (ANOVA) was performed on the experimental results to investigate the contribution of exposure temperature and bar diameter to the tensile behavior of embedded in concrete FRP bars at elevated temperatures. The results show that the tensile strength of embedded FRP bars generally decreases with increasing... 

    Effect of fibers configuration and thickness on tensile behavior of GFRP laminates subjected to elevated temperatures

    , Article Construction and Building Materials ; Volume 202 , 2019 , Pages 189-207 ; 09500618 (ISSN) Jafari, A ; Bazli, M ; Ashrafi, H ; Vatani Oskouei, A ; Azhari, S ; Zhao, X. L ; Gholipour, H ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    This study was aimed at gaining an improved understanding of the behavior of glass fiber-reinforced polymer laminates at elevated temperatures by means of testing laminate specimens with unidirectional, woven, and randomly distributed (chopped strand mat) fibers. The testing parameters were temperature, the type of fiber, and the thickness of the laminates. The failure modes of the specimens and their elasticity moduli at ambient temperature were investigated, and analysis of variance was conducted to determine the contribution of each parameter to the behavioral test results. The findings showed that among the parameters, an increase in temperature exerted the strongest effect on the... 

    Recycled ceramic waste high strength concrete containing wollastonite particles and micro-silica: A comprehensive experimental study

    , Article Construction and Building Materials ; Volume 201 , 2019 , Pages 11-32 ; 09500618 (ISSN) Zareei, S. A ; Ameri, F ; Shoaei, P ; Bahrami, N ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    This study investigated the effects of combined utilization of wollastonite particles and recycled waste ceramic aggregate (RWCA) on high strength concrete (HSC) properties. Two groups of mixtures were manufactured: 1) concrete mixtures in which cement was partially replaced with wollastonite at values ranging from 10% to 50%, and 2) mixtures in which wollastonite was used at the aforementioned dosages and 50% of natural coarse aggregate was replaced with RWCA. In addition, 10% of cement weight micro-silica was added to all mixtures. The concrete behavior in terms of strength, durability, resistance against acidic environment, and performance under elevated temperatures ranging from 20 °C to... 

    Elevated-temperature behaviour of LiNi0.5Co0.2Mn0.3O2 cathode modified with rGO-SiO2 composite coating

    , Article Journal of Alloys and Compounds ; Volume 843 , 2020 Razmjoo Khollari, M. A ; Khalili Azar, M ; Esmaeili, M ; Tanhaei, M ; Dolati, A ; Hosseini H, S. M ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    An intense decrease in cycling performance and safety is a challenge for elevated temperature application of LiNi0.5Co0.2Mn0.3O2 (NCM) cathode material. In this paper, effect of two types of nano-coatings on improvement of elevated temperature performance of NCM cathode material has been investigated. One of the coatings contains SiO2 nanoparticles and the other one contains composite of reduced graphene oxide and SiO2 nanoparticles (rGO-SiO2). The coatings were fabricated by a facile wet chemical method. The SiO2 coated cathode material showed an excellent elevated temperature cycling stability, however, a decrease in discharge capacity and rate capability of this sample was observed. On... 

    Cementitious mortars containing pozzolana under elevated temperatures

    , Article Structural Concrete ; Volume 23, Issue 5 , 2022 , Pages 3294-3312 ; 14644177 (ISSN) Toufigh, V ; Pachideh, G ; Sharif University of Technology
    John Wiley and Sons Inc  2022
    Abstract
    In recent years, pozzolana are being increasingly used in different types of concretes and mortars. This investigation aims to evaluate the effect of replacing 7, 14, 21, and 28% cement (by weight) with silica fume (SF), granulated blast furnace slag (GBFS), zeolite, and fly ash (FA) under elevated temperatures. Forty mix designs were built with various water-to-cement ratios and plasticizers. Three hundred and six specimens were prepared, and the flexural, uniaxial compression and tensile tests were performed on specimens after exposure to elevated temperatures between 25°C and 900°C. The X-ray diffraction (XRD) test was then performed on the two series of specimens. Accordingly, the... 

    Al-Al3Ti nanocomposite produced in situ by two-step hot-press sintering

    , Article IOP Conference Series: Materials Science and Engineering ; Volume 40, Issue 1 , 2012 ; 17578981 (ISSN) Nikfar, B ; Ghiabakloo, H ; Hosseini, H. R. M ; Mohammadi, A. V ; Sharif University of Technology
    2012
    Abstract
    Aluminum reinforced with a large amount (up to about 55 vol.%) of Al 3Ti particles can be fabricated from Al-20Ti elemental nanometer-sized powder mixture via in-situ two step hot press sintering (TSS). For production of intermetallic reinforced in-situ composite, TSS can provide elevated temperature to facilitate the formation of intermetallic phase in situ and hot consolidation to form a fully dense solid. The first step sintering was employed at a higher temperature to obtain an initial high density, and the second step was held at a lower temperature by isothermal sintering for more time than the first one to increase bulk density without significant grain growth. The optimum TSS regime... 

    Mechanisms governing microstructural evolution during consolidation of nanoparticles

    , Article Materials and Manufacturing Processes ; Volume 30, Issue 11 , 2015 , Pages 1397-1402 ; 10426914 (ISSN) Tavakol, M ; Mahnama, M ; Naghdabadi, R ; Sharif University of Technology
    Taylor and Francis Inc  2015
    Abstract
    In micron-scale, powder consolidation process is driven by diffusion phenomenon, while in nano-scale the higher surface energy of particles leads to some anomalous behaviors within the process. In order to investigate the nano-sintering occurrence, an atomistic approach is employed via molecular dynamics simulations. Within this approach, the effect of particle size and temperature is examined. The study of particle structure emphasizes on a transition on the governing mechanism of process depending on the material energy levels. The results show that in a specific particle size at low temperatures, the main sintering mechanism is the plastic deformation, while at elevated temperatures it... 

    Effect of intumescent paint coating on mechanical properties of FRP bars at elevated temperature

    , Article Polymer Testing ; Volume 71 , 2018 , Pages 72-86 ; 01429418 (ISSN) Houshmand Khaneghahi, M ; Pournamazian Najafabadi, E ; Shoaei, P ; Vatani Oskouei, A ; Sharif University of Technology
    Abstract
    This paper investigates the influence of intumescent paint on the performance of FRP bars subjected to low (25–450 °C) and severe (450–800 °C) elevated temperatures. In this research, glass and carbon FRP bars with epoxy resin and coated with nitrogen-based intumescent paint were used. In addition to the temperature effects, a variety of FRP bar diameters were employed to determine its effect on the tensile behavior of FRP bars in the presence of intumescent paint. Further, Bayesian regression methods and ANOVA (ANalysis Of VAriance) were applied on the results to develop a predictive model form and quantify the contribution of the variables in the tensile performance of FRP bars,... 

    The effects of intermediate and post-annealing phenomena on the mechanical properties and microstructure of constrained groove pressed copper sheet

    , Article Materials Science and Engineering A ; Volume 515, Issue 1-2 , 2009 , Pages 162-168 ; 09215093 (ISSN) Rafizadeh, E ; Mani, A ; Kazeminezhad, M ; Sharif University of Technology
    2009
    Abstract
    Commercial purity copper sheets were subjected to a severe plastic deformation technique known as constrained groove pressing (CGP). The effect of pass number, intermediate and post-annealing on the yield strength, hardness and final microstructure of the copper specimens were investigated. The initial pass increases the strength much more than the subsequent passes. Intermediate and post-annealing up to 300 °C cannot change the mechanical properties significantly and even in some cases improve the strength and hardness while reduce the hardness inhomogeneity. Microstructure after post-annealing at elevated temperatures shows abnormal grain growth. © 2009 Elsevier B.V. All rights reserved