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fiber-reinforced-polymers
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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) ; Mahsuli, M ; Talebiyan, H ; Kashani, H ; Sharif University of Technology
Abstract
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...
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) ; 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...
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) ; Toufigh, V ; Mofid, M ; Sharif University of Technology
Springer Verlag
2018
Abstract
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...
The effect of elevated temperatures on the compressive section capacity of pultruded GFRP profiles
, Article Construction and Building Materials ; Volume 249 , July , 2020 ; 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
Behavior of square concrete columns strengthened with Carbon Fiber Reinforced Polymer (CFRP) strips
, Article 1st International Conference on Concrete Repair, Rehabilitation and Retrofitting, ICCRRR 2005, Cape Town, 21 November 2005 through 23 November 2005 ; 2006 , Pages 471-473 ; 0415396549 (ISBN); 9780415396547 (ISBN) ; Moghaddam, H ; Sharif University of Technology
2006
Abstract
Reinforced concrete columns with insufficient transverse steel reinforcement are not capable to dissipate seismic energy due to lack of necessary ductility. In this research, six RC columns with poor transverse reinforcements are tested under cyclic and axial loads as control columns and retrofitted ones. Prestressed and non-pre-stressed CFRP strips used as external transverse reinforcement to evaluate the benefits of active and passive confinement. Results indicate that additional confinement due to the use of CFRP strips enhances the strength, ductility and energy dissipation capacity of columns. The advantages of active confinement versus passive confinement are demonstrated too. © 2006...
Behavior of Concrete Slabs Reinforced with FRP Bars, Design and Analysis
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
Despite extensive studies on the behavior of reinforced concrete slabs, especially those reinforced with steel rebars, no comprehensive studies have been conducted on the behavior of concrete slabs reinforced with FRP rebars. Therefore, there are some ambiguities regarding the tensile and compressive behavior of these rebars in the load-bearing capacity of reinforced concrete slabs (depending on their amount in the slab and their combination with steel rebars). Hence, in this study, in order to ensure the accuracy of numerical simulations, the numerical 3D simulation of a one-way concrete slab reinforced with tensile FRP rebars was performed using the finite element Abaqus software....
Dynamic performance of concrete slabs reinforced with steel and GFRP bars under impact loading
, Article Engineering Structures ; Volume 191 , 2019 , Pages 62-81 ; 01410296 (ISSN) ; Khaloo, A ; Soltani, H ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
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. This study investigated the effect of rebar's material, amount and arrangement of reinforcements, concrete strength and slab thickness on dynamic behavior of reinforced concrete slabs using both laboratory experiments and numerical simulations. Performance of fifteen 1000 × 1000 mm concrete slabs, including two 75 mm thick plain slabs,...
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...
Numerical Analysis on Flexural Behavior of Concrete Beams Reinforced with FRP bars
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
The main problem of steel-reinforced concrete structures is corrosion of steel reinforcements which leads to premature failure of the concrete structures. This problem costs a lot annually to rehabilitate and repair these structures. In order to improve the longterm performance of reinforced concrete structures and for preventing this corrosion problem, Fiber Reinforced Polymer (FRP) bars can be substituted of conventional steel bars for reinforcing concrete structures. This study is a numerical study to evaluate structural behavior of the simply supported concrete beams reinforced with FRP bars in comparison with steel-reinforced concrete beams. The commercial Finite Element Modeling...
Effect of Carbon and Glass FRP Confinement on Compressive Strength of Pre-Damaged Concrete Cylinders
, M.Sc. Thesis Sharif University of Technology ; Joghatae, Abdolreza (Supervisor)
Abstract
Recent investigations on construction engineering have determined that repairing of Reinforced Concrete (RC) by means of fiber reinforced polymer (FRP) composites is an effective method of retrofitting existing columns. The main research in this thesis focuses on the repair of concrete specimens which are damaged and their initial strength has been reduced. To achieve this purpose, through experimental procedures, the effect of confining damaged concrete cylinders by FRP, has been investigated. The experimental program included three parameters: type of fibers (glass or carbon), type of confining (full or partial), and the number of layers. First concrete cylinders were made and loaded to...
Seismic Analysis of Shear Wall Frames Retrofited by FRP with Endurance Time Method
,
M.Sc. Thesis
Sharif University of Technology
;
Estekanchi, Homayoon
(Supervisor)
Abstract
This study has been carried out for investigating the need for an appropriate and fast seismic analysis method to be applied in performance based design (PBD), and show the application of Endurance Time (ET) method and its advantages in PBD. The major goal of this project is analysis and study of behavior of concrete frames with retrofitted shear walls with FRP by ET method with acceleration functions which are compatible with actual earthquake and comparation with time history analysis, forand comparation of whole results with shear wall frames that are not retrofitted. Performance criteria of FEMA code were used fore comparation of two frame categories (retrofitted and not retrofitted)....
Behavior of RC Concrete Column Strengthened with CFRP, Steel Jacketand Reinforced Concrete Jacket
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
Reinforced concrete (RC) column in building often needs strengthening either due to defects in the column themselves, having to support higher loads than those foreseen in the initial design of the structure or as the result of ageing or accidental damage such as earthquake force. The use of FRP wrapping, steel caging or reinforce concrete jacketing for this purpose is now a common practice in many countries throughout the world. Even though a considerable number of researches have been conducted on retrofitting methods during past years, but very limited researches have been done to compare these methods. This research has investigated the effect of jacketing from different views. The...
Seismic Behavior Comparison of RC Shear Walls Strengthened Using FRP Composites, Steel Elements, and Concrete Jacket
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
This paper aims at investigating the seismic behavior of strengthened reinforced concrete (RC) shear walls using a 3D finite element analysis. A series of four different configurations of carbon fiber reinforced polymer (CFRP) composites, four different schemes of steel elements and two different schemes of concrete jacket are utilized to compare the two methods of retrofitting RC shear walls with similar dimensions and reinforcement ratios. Nonlinear simulations of the RC shear walls are conducted under the action of lateral cyclic loading in ABAQUS Explicit software. In addition, the numerical modeling for RC walls strengthened by CFRP composites as well as steel elements are validated...
The Durability of Geopolymer Concrete Confined with Fiber Reinforced Polymer Materials
, M.Sc. Thesis Sharif University of Technology ; Toufigh, Vahab (Supervisor)
Abstract
Material durability is quite critical in corrosive environments. In this study, two hundred and seventy geopolymer concrete specimens with different mix designs were prepared and then wrapped with two different fiber reinforced polymer (FRP) materials. For 12960 hrs (eighteen months), the specimens were exposed to four different pHs (2.5, 7, 7.25, 12.5). The reliability and SEM analysis were performed after modeling the compressive strength over time. Based on the results, the reduction of the compressive strength was up to 22% in an acidic environment. The compressive strength of the specimens was increased up to 11 percent after alkaline solution exposure. The ductility of all specimens...
Experimental Investigation on the Behavior of RC Arches Strengthened by GFRP and CFRP Composites
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
The rehabilitation of old structures holds a lot of importance, as many structures with a life span of over 30 years are prone to severe damage and even collapse. To overcome this problem, the use of FRP sheets to strengthen structures is suggested. RC-arches have been used in many structures such as bridges and require specific consideration in terms of strengthening. So far, the influence of the number of FRP layers and location, the height of arch and percentage of reinforcement on strengthened arch behavior have not been investigated. In this research, reinforced concrete arch members strengthened with GFRP and CFRP were investigated. A total of 28 Specimens, including four...
Dynamic Performance Enhancement of RC Slabs by Steel Fibers vs. Externally Bonded GFRP Sheets under Impact Loading
, Ph.D. Dissertation Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
Recently, to improve the dynamic behavior of Reinforced Concrete (RC) slabs under impact load, the methods of externally bonding Glass Fiber Reinforced Polymer (GFRP) sheets to slab and internally reinforcing concrete by steel fibers have been proposed. Nevertheless, it is required to investigate the comparison between these two methods on response of RC slabs under impact loads. In this study, the influence of volume fraction of steel fibers, the number of GFRP sheet layers (one or two) and the arrangement of GFRP sheets (covering the whole or parts of surface), are examined. Performance of fourteen mm concrete slabs including one plain slab, one steel RC slab, three steel RC slabs...
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) ; 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...
A data mining approach to compressive strength of CFRP-confined concrete cylinders
, Article Structural Engineering and Mechanics ; Volume 36, Issue 6 , Dec , 2010 , Pages 759-783 ; 12254568 (ISSN) ; Alavi, A. H ; Gandomi, A. H ; Arab Esmaeili, M ; Gandomi, M ; Sharif University of Technology
2010
Abstract
In this paper, compressive strength of carbon fiber reinforced polymer (CFRP) confined concrete cylinders is formulated using a hybrid method coupling genetic programming (GP) and simulated annealing (SA), called GP/SA, and a robust variant of GP, namely multi expression programming (MEP). Straightforward GP/SA and MEP-based prediction equations are derived for the compressive strength of CFRP-wrapped concrete cylinders. The models are constructed using two sets of predictor variables. The first set comprises diameter of concrete cylinder, unconfined concrete strength, tensile strength of CFRP laminate, and total thickness of CFRP layer. The most widely used parameters of unconfined concrete...
Parametric study of strain rate effects on nanoparticle-reinforced polymer composites
, Article Journal of Nanomaterials ; Volume 2016 , 2016 ; 16874110 (ISSN) ; Haji Gholami, I ; Masajedian, S ; Mertiny, P ; Sameoto, D ; Taheri, F ; Sharif University of Technology
Hindawi Publishing Corporation
2016
Abstract
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) ; Toufigh, V ; Desai, C ; Toufigh, V ; Saadatmanesh, H ; Sharif University of Technology
Techno Press
Abstract
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...