Loading...
Search for: fiber-reinforced-plastics
0.009 seconds
Total 62 records

    Strengthening Reinforced Concrete Deep Beams Using FRP Systems

    , M.Sc. Thesis Sharif University of Technology Mesgarian, Iman (Author) ; Kazemi, Mohammad Taghi (Supervisor)
    Abstract
    In recent years, the development of the plate bonding repair technique has been shown to be applicable to many existing strengthening problems in the building industry. This technique may be defined as one in which composite sheets or plates of relatively small thickness are bonded with an epoxy adhesive to, in most cases, a concrete structure to improve its structural behaviour and strength. The sheets or plates do not require much space and give a composite action between the adherents. The old structure and the new bonded-on material create a new structural element that has a higher strength and stiffness than original one. According to the available methods of analysis and design for... 

    A Study on the Effect of Different Lubrication Methods on Surface Integrity and Tool Wear during Ultrasonic-Assisted Milling of CFRP

    , M.Sc. Thesis Sharif University of Technology Amirnia, Mahan (Author) ; Akbari, Javad (Supervisor)
    Abstract
    The aim of this study was to compare the effect of different cooling conditions (dry, flood, mql) on machined surface parameters (smoothness and protrusion of fibers) and tool erosion in carbon fiber reinforced plastic composite materials (CFRP) in the presence of ultrasonic vibrations or without it. Is. Today, carbon fiber reinforced plastic composite materials or CFRP have become one of the most widely used materials in industry due to their strength and light properties. For example, these materials have been used in the manufacture of products from commercial aircraft to shoes, tennis rackets, golf clubs, fishing rods, etc. The combination of carbon fibers woven with resin in alternating... 

    Fracture Modeling of Strengthened Arc Concrete Structures with FRP by Concrete Damage Plasticity and XFEM

    , M.Sc. Thesis Sharif University of Technology Navid Tehrani, Yousef (Author) ; Khoei, Amir Reza (Supervisor)
    Abstract
    Usage of FRP material is developed in recent year, because advantages of this material researcher studied the effect of this strengthening method on beam column and masonry structures, but few research’s related to RC arches that strengthen with FRP. This studies showed performance of structure properties but many parameters influence. In this research, a model developed that can model RC arch with FRP till complete failure, after verifying model with experimental result parametric study done. This parameter are effect of strengthening scheme, influence of shape of arch and geometry of arches. Concrete damage plasticity used for modeling behavior of concrete, also for modeling interface... 

    Fabrication and Investigation of Structure and Mechanical Properties of Bagasse Fibers Reinforced PP: Role of Alkalization and Calcium Carbonate Filler

    , M.Sc. Thesis Sharif University of Technology Asgharpour, Ali (Author) ; Bagheri, Reza (Supervisor)
    Abstract
    The consumption of plastics in the world is increasing and this is accompanied by the challenges of production from oil products and carbon footprint, waste production and environmental issues. The solutions to these challenges are material recycling and the production of biocompatible plastics. Polypropylene is a widely used polymer that is commonly used in conjunction with reinforcements such as fiberglass. Natural fibers can be substituted to increase the biocompatibility of the composite, which, despite its many advantages, presents challenges. The most important challenge is the poor adhesion of the fibers and the matrix due to the hydrophilicity of natural fibers and hydrophobicity of... 

    Behavior of Concrete Frames Reinforced with FRP Bars

    , M.Sc. Thesis Sharif University of Technology Tafarroji, Armin (Author) ; Khaloo, Alireza (Supervisor)
    Abstract
    FRP rebars due to various properties such as high resistance to weight ratio, high corrosion resistance, high tensile strength, low weight, resistance to electrical and magnetic conductivity, and other desirable properties, have always been an interesting topic for researchers as an alternative to steel rebars in special conditions.In this research, a two-dimensional sway intermediate concrete frame with three stories and two bays reinforced with GFRP bars was designed and studied. Unlike previous researches and design codes, the compressive strength of the bars was considered in the design process. With computer coding in Matlab software, column interaction diagrams and a special contour... 

    Effect Of Longitudinally Ultrasonic Assisted Milling On Surface Integrity of CFRP Composites

    , M.Sc. Thesis Sharif University of Technology Charkhian, Ali (Author) ; Akbari, Javad (Supervisor)
    Abstract
    Nowadays, processes with the ability to machine advanced materials are very much needed by industries. Therefore, compare of a rotary ultrasonic-assisted machining process with a conventional machining process is carried out in this study. In order to evaluate this process, the milling and drilling processes are conducted on the carbon fiber-reinforced polymer composite and titanium materials where cutting forces, surface roughness, and fiber pull-out are selected as critical factors for analysis. As a result, it is seen that rotary ultrasonic-assisted machining has a good performance in the milling and drilling of advanced materials. In particular, it is shown that fiber pull-out is... 

    Investigation of Dynamic Behavior of Concrete Slabs Reinforced with GFRP Bars and Prestressed Concrete Slabs under Impact Loading

    , Ph.D. Dissertation Sharif University of Technology Sadraie, Hamid (Author) ; Khaloo, Alireza (Supervisor)
    Abstract
    Prestressed and reinforced concrete slabs are common structural elements that could be exposed to impact loading. Although, use of reinforced concrete slabs and utilization of Fiber Reinforced Polymer (FRP) as alternative to traditional steel reinforcement slabs are growing, but the influence of various parameters on their response under impact loads is not properly evaluated. In addition, studies on steel reinforced concrete slabs have been found in literature, but investigation of prestressed slabs and GFRP reinforced concrete slabs under impact load is limited. This study investigated the effect of rebar’s material, amount and arrangement of reinforcements, concrete strength and slab... 

    Time-varying structural reliability assessment method: Application to fiber reinforced composites under repeated impact loading

    , Article Composite Structures ; 2020 Saraygord Afshari, S ; Pourtakdoust, S. H ; Crawford, B. J ; Seethalerc, R ; Milani, A. S ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    Reliability evaluations play a significant role in engineering applications to ensure the serviceability and safety of advanced structures such as those made of composites. Here, a dynamic reliability evaluation analysis based on the probability density evolution Method (PDEM) has been adapted to assess the reliability of composite structures under uncertainties within the material properties and the external loadings. A Back-Propagation Neural Network approach is employed to identify the system's nonlinear structural response, which is often the case under large deformations. To exemplify, a split Hopkinson pressure bar system was employed to mimic the mechanical behavior of a... 

    Time-varying structural reliability assessment method: Application to fiber reinforced composites under repeated impact loading

    , Article Composite Structures ; Volume 261 , 2021 ; 02638223 (ISSN) Afshari, S. S ; Pourtakdoust, S. H ; Crawford, B. J ; Seethaler, R ; Milani, A. S ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    Reliability evaluations play a significant role in engineering applications to ensure the serviceability and safety of advanced structures such as those made of composites. Here, a dynamic reliability evaluation analysis based on the probability density evolution Method (PDEM) has been adapted to assess the reliability of composite structures under uncertainties within the material properties and the external loadings. A Back-Propagation Neural Network approach is employed to identify the system's nonlinear structural response, which is often the case under large deformations. To exemplify, a split Hopkinson pressure bar system was employed to mimic the mechanical behavior of a... 

    Time-varying structural reliability assessment method: Application to fiber reinforced composites under repeated impact loading

    , Article Composite Structures ; Volume 261 , 2021 ; 02638223 (ISSN) Afshari, S.S ; Pourtakdoust, S. H ; Crawford, B. J ; Seethaler, R ; Milani, A. S ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    Reliability evaluations play a significant role in engineering applications to ensure the serviceability and safety of advanced structures such as those made of composites. Here, a dynamic reliability evaluation analysis based on the probability density evolution Method (PDEM) has been adapted to assess the reliability of composite structures under uncertainties within the material properties and the external loadings. A Back-Propagation Neural Network approach is employed to identify the system's nonlinear structural response, which is often the case under large deformations. To exemplify, a split Hopkinson pressure bar system was employed to mimic the mechanical behavior of a... 

    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... 

    The long-term evaluation of FRPs bonded to timber

    , Article European Journal of Wood and Wood Products ; Volume 76, Issue 6 , 2018 , Pages 1623-1636 ; 00183768 (ISSN) Toufigh, V ; Yarigarravesh, M ; Mofid, M ; Sharif University of Technology
    Abstract
    This research investigated the long-term environmental effects on bond strength at the interface between fiber- reinforced polymers (FRPs) and timber. A total of 581 timber specimens were bonded with seven types of FRP sheets (unidirectional and bidirectional glass, carbon, aramid, and hybrids) using a wet lay-up technique. The specimens were exposed to acidic, alkaline, fresh water, and sea water solutions with pH of 2.5, 7, 7.25, 10, and 12.5 for 1, 3, 6, 9, and 12 months. A chamber was also used to simulate ultraviolet radiation after 6 months. A series of single-lap shear tests were then conducted to determine the interfacial bond strength reduction. The results showed that bidirectional... 

    The effects of elevated temperatures on the performance of concrete-filled pultruded GFRP tubular columns

    , Article Thin-Walled Structures ; Volume 169 , 2021 ; 02638231 (ISSN) Tabatabaeian, M ; Khaloo, A ; Azizmohammadi, M ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    Usage of concrete-filled pultruded glass fiber-reinforced polymer (GFRP) tubes (CFPGT) as columns can increase the service life of structures. However, marine structures such as oil platforms are always prone to fire because of the low resistance to the elevated temperatures. The purpose of this investigation is to evaluate the effects of concrete core strength (30 and 60 MPa), and exposure temperature (25, 100, 200, 300, and 400 °C) and time (60 and 120 min) on the compressive and bond behavior of CFPGTs. The properties of unexposed and exposed concrete core, pultruded GFRP hollow tubes, and CFPGTs were determined via compressive and disk-split tests. Also, the push-out test was used to... 

    The effect of transverse steel and FRP jacket confinement on mechanical properties of concrete cylinders: An experimental study

    , Article ISEC 2011 - 6th International Structural Engineering and Construction Conference: Modern Methods and Advances in Structural Engineering and Construction ; 2011 , Pages 827-832 ; 9789810879204 (ISBN) Khaloo, A. R ; Javid, Y ; Khosravi, H ; Yazdani S ; Cheung S. O ; Singh A ; Ghafoori N ; American Society of Civil Engineers (ASCE); Architectural Institute of Japan (AIJ); Chartered Institute of Building (CIOB); et al.; University of Nevada Las Vegas (UNLV), College of Engineering; Wayne State College of Engineering ; Sharif University of Technology
    Abstract
    This paper presents the results of an experimental study on the behavior of concrete cylinders externally wrapped with fiber-reinforced polymer (FRP) composites and internally reinforced with steel spirals. The experimental work was performed by testing 30 concrete cylinders (120 × 400mm2) subjected to pure compression to achieve the complete stress-strain curve. Test specimens were confined with various internal and external confinement ratios and different types of confining material such as steel, Carbon FRP (CFRP) and Glass FRP (GFRP). The compressive strength, corresponding strain and the complete stress-strain curve of the tested specimenswere indicated. The test results showthat the... 

    The effect of mechanical and thermal properties of FRP bars on their tensile performance under elevated temperatures

    , Article Construction and Building Materials ; Volume 157 , 2017 , Pages 1001-1010 ; 09500618 (ISSN) Ashrafi, H ; Bazli, M ; Najafabadi, E. P ; Vatani Oskouei, A ; Sharif University of Technology
    Abstract
    In this experimental study the effect of physical and thermal properties of various FRP bars on their performance under elevated temperatures are investigated. The parameters included the bars' diameter, type of fiber, type of resin, fiber to matrix ratio, and thermal properties were studied. Moreover, ANOVA (ANalysis Of VAriance) was performed in order to investigate the contribution of each variable on the obtained results. The results showed that in addition to the temperature, the bars' diameter, type of fiber, type of resin, and thermal properties (Tg and Td) of the FRP bars have contributions to the results, while the fiber to matrix ratio was found to be an ineffective factor. It was... 

    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... 

    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  

    Strengthening study on 6082 Al alloy after combination of aging treatment and ECAP process

    , Article Materials Science and Engineering A ; Volume 527, Issue 18-19 , July , 2010 , Pages 4758-4766 ; 09215093 (ISSN) Dadbakhsh, S ; Karimi Taheri, A ; Smith, C. W ; Sharif University of Technology
    2010
    Abstract
    Equal channel angular pressing (ECAP) was used before and after various aging treatments in order to strengthen a commercial 6082 Al alloy. Experiments were carried out to study the strengthening of the alloy due to pre and post-ECAP aging treatment. It was found that aging before and after ECAP processing is an effective method for strengthening of the alloy. An increase in both strength and ductility of the ECAPed specimen was achieved via appropriate post-aging treatment. This was in such a manner that for maximal strengthening, post-ECAP aging is best conducted at temperatures lower than those usually used for aging if prior work hardening is not undertaken. Pre-ECAP aging was also... 

    Strengthening of metallic beams with different types of pre-stressed un-bonded retrofit systems

    , Article Composite Structures ; Volume 159 , 2017 , Pages 81-95 ; 02638223 (ISSN) Kianmofrad, F ; Ghafoori, E ; Elyasi, M. M ; Motavalli, M ; Rahimian, M ; Sharif University of Technology
    Elsevier Ltd  2017
    Abstract
    Unlike bonded retrofit systems, un-bonded systems do not need any surface preparation prior to bond application, which reduces the overall time and cost of a retrofit plan. Because the carbon fiber reinforced polymer (CFRP) plate in the un-bonded (tendon) systems is not bonded to a metallic substrate, different variants of the retrofit systems can be developed to ease application in the field. This paper presents four different variants of the prestressed un-bonded retrofit (PUR) systems: trapezoidal PUR (TPUR), triangular PUR (TriPUR), Flat PUR (FPUR), and Contact PUR (CPUR) systems. Analytical solutions based on the flexibility approach are developed to predict the behavior of the metallic... 

    Strengthening design limitations of an RC frames using FRP column wrapping considering column-to-beam strength ratio

    , Article Scientia Iranica ; Volume 14, Issue 5 , 2007 , Pages 405-413 ; 10263098 (ISSN) Khaloo, A. R ; Esmaili, A ; Sharif University of Technology
    Sharif University of Technology  2007
    Abstract
    The aim of this paper is to study the influence of the column-to-beam strength ratio on the seismic strengthening of a column with a Fiber-Reinforced Plastic (FRP) wrapping system. FRP wrapped Reinforced Concrete (RC) columns are analyzed to obtain moment-curvature curves using FRP confined concrete characteristics. A pushover analysis of a 2D model was performed on one and three-story moment-resisting frames, with different column-to-beam strength ratios. The results indicate that FRP strengthening is more efficient in frames with a low ratio of column-to-beam strength, due to the type of lateral failure mechanism of the frame. Also, high values of the column-to-beam strength ratio can be...