Search for: flexural-strength
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    Influence of Notch Location on Fiber Reinforced High-Strength Concrete Beams

    , M.Sc. Thesis Sharif University of Technology Rezaei Saleh, Benyamin (Author) ; Khaloo, Alireza (Supervisor)
    The daily development of societies and the advancement of various industries have led civil engineering to save on and use of environmentally friendly materials. Urban development and population concentration In some areas, Encourages engineers To use materials with more efficiency to design High-rise structures that have more lifetime or maintain them using modern methods. Concrete in most structures has a significant percentage of consumable materials, but it has limited tensile strength and flexibility. Fiber can be used to control the growth of cracks, prolonging useful life, controlling permeability and corrosion. Different types of fibers are used in concrete.In this study, we have... 

    Analysis of the effect of kevlar fibers on abrasion resistance, flexural strength and hydraulic conductivity coefficient of silica fume concretes

    , Article Iranian Journal of Science and Technology - Transactions of Civil Engineering ; Volume 44, Issue 2 , 2020 , Pages 669-674 Rahmani, K ; Piroti, S ; Ghameian, M ; Sharif University of Technology
    Springer  2020
    Reinforcing fiber and silica fume of concrete can be considered as one of the most widely used additives. In this study, with a review of the history and advantages of using silica fume and polypropylene fibers in concrete, 380 concrete laboratory samples were constructed, of which 25 mixing designs with water–cement ratio of 0.35 and fiber content of 0.2, 0.3, 0.4 and 0.5 of concrete volume and 7% silica fume were prepared according to the ACI standard in their manufacturing. In the present research, samples of Kevlar fiber containing silica fume were tested under flexural strength, abrasion resistance and hydraulic conductivity coefficient. According to achieved results, the optimum amount... 

    Shear repair of reinforced concrete beams using post-tensioning

    , Article 4th International Conference on Repair, Rehabilitation, and Maintenance of Concrete Structures, and Innovations in Design and Construction, 19 September 2000 through 22 September 2000 ; Volume SP-193 , 2000 , Pages 519-549 ; 01932527 (ISSN); 9780870316913 (ISBN) Khaloo, A. R ; American Concrete Institute ; Sharif University of Technology
    American Concrete Institute  2000
    In this paper, shear strengthening of RC beams by confining shear critical region is experimentally and theoretically investigated. Confinement is implemented using vertical post-compression force in the shear critical region with steel plate, bolts and angles. The loading tests include (1) loading beams to first major shear crack, then shear strengthening, and reloading to complete failure, (2) strengthening beams from beginning and loading to complete failure, and (3) loading unrepaired beam to complete failure. lnt1uences of concrete strength, shear span length, longitudinal tensile reinforcement, level of post-tensioning, presence of shear reinforcement, use of continuous plates, and... 

    Experimental Studies on Mechanical Properties of Cement Mortar Including Nano Alumina and Nano Silica

    , M.Sc. Thesis Sharif University of Technology Jafari Rahmatabadi, Mohammad Hossein (Author) ; Joghataie, Abdollreza (Supervisor)
    Due to the diameter and size of nanoparticles, they have been applied in various fields to make materials with better properties. In this thesis, the purpose has been to investigate the influence of nano alumina and nano alumina incorporating nano silica particles on mechanical properties of cement mortars. Different portions of nano alumina that include 1, 3, and 5% have been used. Nano silica with 1 and 2% has been used. At first, nano particles were dispersed by sonication with water, and then the cement mortars with various percent of nano additives with the same workability have been made. After different curing periods (7, 28 days), the specimens have been tested for bending and... 

    Flexural Behavior of Concrete Beams Strengthened by Classical Method and Comparing The Results with Strengthening by FRP

    , M.Sc. Thesis Sharif University of Technology Moradkhani Pour, Behnam (Author) ; Khaloo, Alireza (Supervisor)
    Retrofitting and strengthening existing structures is one of the most important concepts of structural and earthquake engineering. Strengthening of structures could be due to changes in application and applied load, errors in calculation, mistakes in construction, weakness of old codes, structural height increases and changes in environmental conditions. Different methods for increasing the flexural strength and ductility of reinforced concrete beams, as one of the major structural components, have been presented. This research presents an experimental study on the strengthening of reinforced concrete beams by reinforced concrete jackets (classical method) and Fiber Reinforced Polymer (FRP)... 

    Experimental Study on Flexural Strength of Notched Fiber Reinforced Concrete Beam

    , M.Sc. Thesis Sharif University of Technology Fartash, Ali (Author) ; Khaloo, Alireza (Supervisor)
    The benefits of fiber reinforced concrete (FRC) have been thoroughly investigated. Much of this work has focused on polypropylene FRC notched beams. Data on the bending behavior of beams with side notch is scarce. A pilot investigation on the compressive behavior of macro-synthetic FRC and on the splitting tensile strength of FRC was carried out. Twenty beam specimens with two different strength of 35 and 60 MPa was tested. The beams dimensions were 15*15*55 centimeter and they were notched at the bottom at mid and side span. Two different notch depth of 5 and 7.5 centimeter was implemented. At the end it was found out addition of fiber decreases compressive strength of 35 Mega Pascal... 

    Influence of Notch Location on Fiber Reinforced High-Strength Concrete Beams

    , M.Sc. Thesis Sharif University of Technology Rezaei Saleh, Benyamin (Author) ; Khaloo, Alireza (Supervisor)
    The daily development of societies and the advancement of various industries have led civil engineering to save on and use of environmentally friendly materials. Urban development and population concentration In some areas, Encourages engineers To use materials with more efficiency to design High-rise structures that have more lifetime or maintain them using modern methods. Concrete in most structures has a significant percentage of consumable materials, but it has limited tensile strength and flexibility. Fiber can be used to control the growth of cracks, prolonging useful life, controlling permeability and corrosion. Different types of fibers are used in concrete. In this study, we have... 

    Laboratory Study of Fracture Parameters of Ultra-High Performance Fiber Reinforced Concrete

    , M.Sc. Thesis Sharif University of Technology Ebrahimzadeh, Mohsen (Author) ; Kazemi, Mohammad Taghi (Supervisor)
    High performance concrete has a compressive strength of more than one hundred and twenty MPa. The effect of steel fibers on the flexural fracture of this type of concrete has been studied, but the mechanical behavior of fracture of this material has not been fully studied yet. In this research, the effect of different percentages of propylene fibers on the mechanical properties of reinforced concrete will be investigated experimentaly. For this purpose, beam samples with dimensions of 40*10*10 cm, which had an initial notch with a depth of 3 cm in the lower middle of it, have been tested to investigate the effect of fiber percentage on how the crack propegate and the sample breaks. It is... 

    Experimental study of RC jacketed and CFRP strengthened RC beams

    , Article Construction and Building Materials ; Volume 95 , October , 2015 , Pages 476-485 ; 09500618 (ISSN) Tahsiri, H ; Sedehi, O ; Khaloo, A ; Raisi, E. M ; Sharif University of Technology
    Elsevier Ltd  2015
    This paper presents the results of an experimental study on retrofitting RC beams using FRP strengthening and RC jacketing. Three-point loadings are applied to twelve strengthened beams and three reference specimens to put the two techniques into perspective. Formation of first cracks, FRP debonding, and onset of concrete crushing are compared and discussed. Load-deflection behavior, failure modes, and crack propagation patterns are studied extensively. The experiments demonstrate that the RC jacketed beams exhibit a flexural failure identical to the reference beams. However, the FRP strengthened beams fail in a relatively small deflection due to the premature FRP debonding. Furthermore, 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
    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... 

    Evaluation of Seismic Behavior of Coupling Beam in Shear Walls

    , M.Sc. Thesis Sharif University of Technology Arianfar, Roshan (Author) ; Moghaddam, Hassan (Supervisor)
    In evaluating the damage observed in the structures can be seen that the beam to the wall connection in the walls with openings has severe damage and repair and reconstruction of the beams at the connection is very expensive and difficult. One way to improve seismic behavior and reduce damage in the beams are using steel fibers. Hence in the present study the effect of different fibers in seismic behavior of coupling beams with different length to depth ratio are investigated. The concrete used in the beams of high strength concrete (C60). Therefore, nine model with length to depth ratio of 1.75, 2.25 and 2.75 first without fiber and then with 1.5 and 3 percent made in ABAQUS software. This... 

    Flexural Strengthening of Reinforced Concrete Beams by FRP Composites to Reduce Creep Deflection

    , M.Sc. Thesis Sharif University of Technology Zarringol, Mohammad Reza (Author) ; Kazemi, Mohammad Taqhi (Supervisor)
    The strengthening of reinforced concrete structures with externally bonded fibre reinforced polymer (FRP) laminates has shown excellent performance, so this technology is rapidly replacing externally bonded steel plates, steel or concrete jackets, and many traditional techniques available. In this study strengthening of reinforced concrete beams by GFRP to reduce creep deflection is investigated by mathematical method using available relations. Five RC beams with different dimensions, with and without strengthening with GFRP laminate, were investigated for their creep deflection. The creep coefficient of beams selected from experimental result that were mentioned in RILEM DATA BANK. In this... 

    Effect of Zirconia Content and Powder Processing on Mechanical Properties of Gelcasted ZTA Composite

    , Article Transactions of the Indian Ceramic Society ; Volume 72, Issue 3 , May , 2013 , Pages 175-181 ; 0371750X (ISSN) Khoshkalam, M ; Faghihi Sani, M. A ; Nojoomi, A ; Sharif University of Technology
    Addition of fine zirconia particles in the alumina matrix in order to produce ZTA composite is a well-known method for improving the mechanical properties of alumina ceramics such as flexural strength and fracture toughness. Increasing homogeneity and reducing alumina grain size are two key factors for achieving proper mechanical properties in this ceramic matrix composite. In this work two batches of ZTA powder precursor were prepared through mixing of alumina and zirconia by ball milling and in situ synthesis of ZTA composite via solution combustion method. The bending strength testing samples were fabricated through gel-casting process. The effects of different powder processing methods... 

    Effects of pozzolans together with steel and polypropylene fibers on mechanical properties of RCC pavements

    , Article Construction and Building Materials ; Volume 26, Issue 1 , January , 2012 , Pages 102-112 ; 09500618 (ISSN) Madhkhan, M ; Azizkhani, R ; Torki Harchegani, M. E ; Sharif University of Technology
    Effects of pozzolans and fibers on mechanical properties of RCC are addressed. The mechanical properties were evaluated using optimum moisture with different amounts of pozzolans, steel and polypropylene fibers. Using pozzolans, maximum increase in compressive strength was observed to occur between 28 and 90 days of age, rupture modulus was found to decrease; but toughness indices did not change considerably. The influence of steel fibers on compressive strength was often more significant than that of PP fibers; but neither steel nor PP fibers did contribute to increase in the rupture modulus independently from pozzolans. Also, the toughness indices increased when steel fibers were used  

    Waste ceramic powder-based geopolymer mortars: effect of curing temperature and alkaline solution-to-binder ratio

    , Article Construction and Building Materials ; Volume 227 , 2019 ; 09500618 (ISSN) Shoaei, P ; Musaeei, H. R ; Mirlohi, F ; Narimani zamanabadi, S ; Ameri, F ; Bahrami, N ; Sharif University of Technology
    Elsevier Ltd  2019
    In this study, the optimum curing temperature and alkaline solution-to-binder (S:B) ratio of geopolymer mortars based on waste ceramic powder (WCP) were investigated. For this purpose, mixes with S:B ratios of 0.4–0.7 were prepared and cured at 60, 75, 90, and 105 °C. The density, compressive and flexural strengths were measured at 3, 7, 14, and 28 days. Higher S:B ratios enhanced the flow of the fresh mortar. The optimum mortar was obtained for S:B ratio of 0.6 and curing temperature of 90 °C. The SEM analysis revealed that the optimal mix had a dense matrix with minimum pores. © 2019 Elsevier Ltd  

    Mechanical characteristics of cement paste in the presence of carbon nanotubes and silica oxide nanoparticles: An experimental study

    , Article Materials ; Volume 14, Issue 6 , 2021 ; 19961944 (ISSN) Karakouzian, M ; Farhangi, V ; Farani, M. R ; Joshaghani, A ; Zadehmohamad, M ; Ahmadzadeh, M ; Sharif University of Technology
    MDPI AG  2021
    Considering the remarkable characteristics of nanomaterials, previous research studies investigated the effects of incorporating different types of these materials on improving the concrete properties. However, further studies are required to evaluate the complementary hybridization and synergistic influence of nanomaterials. In this research, the combined effect of adding nano silica particles (NS) and multi-walled carbon nanotubes (MWCNT) on enhancing both the compressive and flexural strengths of the cement paste was investigated. Moreover, the morphology of the interface between cement paste and aggregates was studied by scanning electron microscopy (SEM). The mixtures were prepared... 

    Finite Element Modeling of Flexural Behavior of RC Beams Using FRP

    , M.Sc. Thesis Sharif University of Technology Jafarzadeh Eslami, Mehran (Author) ; Rahimzadeh Rofooei, Fayyaz (Supervisor)
    The flexural behavior of reinforced concrete beams through application of FRP is studied, considering FRP-concrete bonding. Moreover, the nonlinear behavior of concrete (generation of crack and crush) is taken into consideration. Different parameters such as the number of layers of CFRP sheets, the effect of tensile reinforcing bars, the effect of using glass fibers, and modeling resin layer between the concrete and FRP are investigated. The results are compared with the existing experimental tests and those obtained from analytical method, ACI 440.2R-08 and ISIS Canada. The results show that by adding CFRP sheet to the control beam, the stiffness and flexural strength of the beam improves... 

    Flexural Failure Mechanism of Concrete Beams Strengthened with FRP and Comparing The Result With Classic Method Of Strengthening

    , M.Sc. Thesis Sharif University of Technology Tahsiri, Hamid Reza (Author) ; Khaloo, Alireza (Supervisor)
    Retrofitting of reinforced concrete and steel structures is a very important issue in Structural Engineering due to the reasons such as drawbacks in previous codes, revision of application of structures , destructive environmental factors and deficiencies in construction process.
    Strengthening of structures with FRP composites is one of the methods that have been welcomed by researchers due to its unique properties including high tensile strength, light weight, simple application and resistance to corrosive environment. Although the main purpose of retrofitting is to increase the overall load carrying capacity of the structures, the failure mechanism of the strengthened member is also... 

    Improving the performance of cement-based composites containing superabsorbent polymers by utilization of nano-SiO2 particles

    , Article Materials and Design ; Volume 42 , 2012 , Pages 94-101 ; 02641275 (ISSN) Pourjavadi, A ; Fakoorpoor, S. M ; Khaloo, A ; Hosseini, P ; Sharif University of Technology
    The application of superabsorbent polymer (SAP) as an internal curing agent for cement based composites results in benefits such as reduced autogenous shrinkage and cracking. However, a reduction in compressive and flexural strength usually occurs due to the empty voids remained in the matrix after deswelling of SAP particles. Nanoparticles are good candidates for improving the mechanical performance of cementitious materials, due to their multiple mechanisms of action, not the least their high pozzolanic activity.In the present work, the capability of amorphous nano-SiO2 (NS) as the most widely used nanoparticle in cementitious materials, for retrieving mechanical properties of... 

    Effects of nucleation agent particle size on properties, crystallisation and microstructure of glass-ceramics in TiO2-ZrO2-Li 2O-CaO- Al2O3-SiO2 system

    , Article Advances in Applied Ceramics ; Volume 109, Issue 6 , 2010 , Pages 318-323 ; 17436753 (ISSN) Nemati, A ; Goharian, P ; Shabanian, M ; Afshar, A ; Sharif University of Technology
    The objective of this study was to evaluate the effects of P 2O5 particle size distribution on the crystalline phases and microstructure of lithium disilicate glass-ceramics derived from the TiO2-ZrO2-Li2O-CaO-Al2O 3-SiO2 system for dentistry applications. The samples were made via fusion and casting procedure. Crystallisation as well as the morphology and microstructure of the samples were investigated using X-ray diffraction, differential scanning calorimetric and scanning electron microscopy. The results showed that the crystallisation of the samples occurred in the range of 500-650°C. The main crystalline phase was lithium disilicate (Li2Si2O5) along with Lithium metasilicate (Li2SiO3),...