Search for: fiber-reinforced-plastics
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    Experimental investigation of square RC column strengthened with near surface mounted GFRP bars subjected to axial and cyclic lateral loads

    , Article Scientia Iranica ; Volume 20, Issue 5 , 2013 , Pages 1361-1371 ; 10263098 (ISSN) Dayhim, N ; Nicknam, A ; Barkhordari, M. A ; Hosseini, A ; Mehdizad, S ; Sharif University of Technology
    Sharif University of Technology  2013
    This article is intended to highlight the effectiveness of longitudinal Glass Fiber Reinforced Polymer (GFRP) bars in combination with GFRP sheets on the flexural capacity of Reinforced Concrete (RC) columns. Seven half-scale RC columns including five strengthened and two control unstrengthened specimens were experimentally tested under axial and cyclic lateral loads. The strengthened columns with two different longitudinal GFRP bar ratios were tested under three different axial load levels. The flexural strength and ductility parameters of the specimens were calculated by obtaining their deformations and measuring the loads from load cells. The experimental results indicate significant... 

    Free vibration analysis of multilayered composite cylinder consisting fibers with variable volume fraction

    , Article Composite Structures ; Volume 94, Issue 3 , 2012 , Pages 931-944 ; 02638223 (ISSN) Kargarnovin, M. H ; Hashemi, M ; Sharif University of Technology
    In this paper, free vibration of a fiber reinforced composite cylinder in which volume fraction of its fibers vary longitudinally, is studied using a semi-analytical method. The distribution of volume fraction of fiber in base matrix is based on power law model. A micromechanical model is employed to represent its mechanical properties including elastic and physical properties of this composite cylinder. In addition, kinematically the first order shear deformation shell theory is employed for strain field. Then, weak form formulation and spatial approximations of variables are utilized to discretize the equations of motion. Different problems are solved in which primarily the validity of the... 

    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
    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... 

    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
    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... 

    Parametric study of strain rate effects on nanoparticle-reinforced polymer composites

    , Article Journal of Nanomaterials ; Volume 2016 , 2016 ; 16874110 (ISSN) Soltannia, B ; Haji Gholami, I ; Masajedian, S ; Mertiny, P ; Sameoto, D ; Taheri, F ; Sharif University of Technology
    Hindawi Publishing Corporation  2016
    Crashworthiness, energy absorption capacity, and safety are important factors in the design of lightweight vehicles made of fiber-reinforced polymer composite (FRP) components. The relatively recent emergence of the nanotechnology industry has presented a novel means to augment the mechanical properties of various materials. As a result, recent attempts have contemplated the use of nanoparticles to further improve the resiliency of resins, especially when resins are used for mating FRP components. Therefore, a comprehensive understanding of the response of nanoreinforced polymer composites, subjected to various rates of loading, is of paramount importance for developing reliable structures.... 

    Finite element analysis of a CFRP reinforced retaining wall

    , Article Geomechanics and Engineering ; Volume 10, Issue 6 , 2016 , Pages 757-774 ; 2005307X (ISSN) Ouria, A ; Toufigh, V ; Desai, C ; Toufigh, V ; Saadatmanesh, H ; Sharif University of Technology
    Techno Press 
    Soils are usually weak in tension therefore different materials such as geosynthetics are used to address this inadequacy. Worldwide annual consumption of geosynthetics is close to 1000 million m2, and the value of these materials is probably close to US$1500 million. Since the total cost of the construction is at least four or five times the cost of the geosynthetic itself, the impact of these materials on civil engineering construction is very large indeed. Nevertheless, there are several significant problems associated with geosynthetics, such as creep, low modulus of elasticity, and susceptibility to aggressive environment. Carbon fiber reinforced polymer (CFRP) was introduced over two... 

    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
    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... 

    Behavior of polymer concrete beam/pile confined with CFRP sleeves

    , Article Mechanics of Advanced Materials and Structures ; 2017 , Pages 1-8 ; 15376494 (ISSN) Toufigh, V ; Toufigh, V ; Saadatmanesh, H ; Ahmari, S ; Kabiri, E ; Sharif University of Technology
    This research investigates the flexural behavior of a polymer concrete beam/pile encased with carbon fiber sleeve. The mechanical properties of carbon fiber sleeves in tension and cement and polymer concrete in compression were determined. Polymer concrete beams were tested in flexure to determine the bending moment capacity. Then, the test results were compared to the theoretical model results. Finally, a parametric study was conducted to determine the influence of beam/pile parameters on the capacity of the element. Based on the investigation, carbon fiber sleeve filled with polymer concrete exhibits outstanding structural performance including ductility and bending capacity. © 2017 Taylor... 

    Polyurethane/clay nanocomposites reinforced with carbon and glass fibres: study of mechanical and thermal properties, and the effect of electron beam irradiation

    , Article Plastics, Rubber and Composites ; Volume 46, Issue 9 , 2017 , Pages 413-420 ; 14658011 (ISSN) Kosari, M ; Mousavian, S. M. A ; Razavi, S. M ; Ahmadi, S. J ; Izadipanah, M ; Sharif University of Technology
    Polyurethane (PU) nanocomposites with 0, 1, 3, 5, and 7 wt-% nanoclay contents were prepared. X-ray diffraction patterns, transmission electron microscopy images, tensile test, and thermogravimetric analysis were utilised to reveal the morphological, mechanical, and thermal-resistant properties of the prepared nanocomposites. The exfoliated structure was obtained for nanoclay contents up to 3 wt-%. Incorporation of nanoclay to the PU matrix prompted the thermal stability of the polymer. A nanocomposite filled with 3 wt-% nanoclay showed the best tensile strength in the prepared nanocomposites. Subsequently, the nanocomposite with the 3 wt-% nanoclay was reinforced with carbon and glass... 

    Environmental effects on the bond at the interface of fiber-reinforced polymer and masonry brick

    , Article Journal of Reinforced Plastics and Composites ; Volume 36, Issue 18 , 2017 , Pages 1355-1368 ; 07316844 (ISSN) Toufigh, V ; Yarigarravesh, M ; Mofid, M ; Sharif University of Technology
    This study examined the bond at the interface of masonry bricks and fiber-reinforced polymer when exposed to five environments. Three fabrics (aramid, carbon, and glass) and one type of epoxy resin were used. A total of 375 brick-fiber-reinforced polymer specimens were made using wet lay-up technic and exposed to chemical solutions at four pH values (2.5, 7, 10, and 12.5) and substitute seawater. The effect of dry heat on the bond at the interface was also investigated. Single-lap shear tests were then carried out on the samples after 2, 4, 6, 8, 10, and 13 weeks of exposure. The experimental results indicated that freshwater and seawater had a considerable effect on the bond strength of... 

    Probabilistic modeling framework for prediction of seismic retrofit cost of buildings

    , Article Journal of Construction Engineering and Management ; Volume 143, Issue 8 , 2017 ; 07339364 (ISSN) Nasrazadani, H ; Mahsuli, M ; Talebiyan, H ; Kashani, H ; Sharif University of Technology
    This study presents a framework that utilizes Bayesian regression to create probabilistic cost models for retrofit actions. Performance improvement is the key parameter introduced in the proposed framework. The incorporation of this novel feature facilitates the characterization of retrofit cost as a continuous function of the desired performance improvement. Accounting for the performance gained from retrofit enables the use of the models in determining the optimal level of retrofit. Furthermore, accounting for the model uncertainty facilitates the use of the models in risk and reliability analyses. The proposed framework is applied to create seismic retrofit cost models for masonry school... 

    Enhancement of bond characteristics of ribbed-surface GFRP bars with concrete by using carbon fiber mat anchorage

    , Article Construction and Building Materials ; Volume 134 , 2017 , Pages 507-519 ; 09500618 (ISSN) Ashrafi, H ; Bazli, M ; Vatani Oskouei, A. V ; Sharif University of Technology
    The bond of fiber-reinforced polymer (FRP) reinforcement is expected to be more sensitive to the strength and geometry of the ribs than conventional steel reinforcement. In this study, the effect of carbon fiber mat anchorage on the pullout behavior of glass fiber-reinforced polymer (GFRP) bars embedded in normal concrete is studied. The studied parameters were the compressive strength of the concrete (16 MPa, 24 MPa, and 37 MPa), and, the length and diameter of the anchorage. In total, 15 variables were studied. Ribbed GFRP bars with 10 mm nominal diameter and 80 mm embedment length, ld, (which is 8 times the bar diameter) were considered. Based on the results for concretes with the... 

    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
    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... 

    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
    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 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
    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... 

    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)
    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... 

    Experimental and analytical evaluation of FRPs bonded to masonry-long term

    , Article Surface and Coatings Technology ; Volume 344 , 25 June , 2018 , Pages 729-741 ; 02578972 (ISSN) Yarigarravesh, M ; Toufigh, V ; Mofid, M ; Sharif University of Technology
    Elsevier B.V  2018
    This research investigated the long-term environmental effects on the bond at the interface between fiber-reinforced polymer (FRP) and a masonry brick. Seven types of FRP fabrics were used and placed on the masonry brick using the wet lay-up technique. Unidirectional and bidirectional fibers made of aramid, carbon, and glass and also combination of these fabrics were used. A total of 525 specimens were exposed to five chemical solutions with pH values of 2.5, 7, 10, 12.5 and substitution sea water for 1, 3, 6, 9 and 12 months. A chamber was also used to simulate the ultraviolent (UV) radiation on the specimens. A series of single-lap shear tests were performed on these specimens to determine... 

    Effect of different retrofitting techniques on in-plane behavior of masonry wallettes

    , Article Construction and Building Materials ; Volume 169 , 2018 , Pages 578-590 ; 09500618 (ISSN) Vatani Oskouei, A ; Jafari, A ; Bazli, M ; Ghahri, R ; Sharif University of Technology
    Elsevier Ltd  2018
    This paper presents the results of diagonal compression tests conducted on a series of un-reinforced and reinforced masonry specimens. Reinforced specimens were strengthened by using three types of mortar coating (with and without inner reinforcement), mesh reinforcement, and PP-band reinforcement. In particular, four different reinforcement methods with mortar coating (bare mortar coating, coating with steel mesh, coating with polymer reinforcement, and coating with GFRP mesh reinforcement), three different mesh-only reinforcement (steel mesh, polymer mesh with larger grids, and polymer mesh with smaller grids), and 2 different arrangements of PP-bands (4 × 4 and 6 × 6) were tested. Also,... 

    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)
    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... 

    Environmental effects on the bond at the interface between FRP and wood

    , Article European Journal of Wood and Wood Products ; Volume 76, Issue 1 , 2018 , Pages 163-174 ; 00183768 (ISSN) Yarigarravesh, M ; Toufigh, V ; Mofid, M ; Sharif University of Technology
    Springer Verlag  2018
    The advantages of fiber reinforced polymer (FRP), such as high specific strength, resistance against corrosion and formability, have made it a more acceptable alternative to conventional materials regarding repairing and retrofitting of structures. Although investigations in recent years have proved the concern of civil engineers about the environmental effects on the bond between FRP and concrete or masonry (especially moisture and temperature), only few researches have been reported on FRP-wood interfaces. This research investigated the effect of five different environments on the bond at the interface between FRP and wood. A series of pull-out tests were performed on 375 wood specimens...