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Buckling of the composite cracked cylindrical shells subjected to axial load
, Article 2003 ASME International Mechanical Engineering Congress, Washington, DC, 15 November 2003 through 21 November 2003 ; Volume 470 , 2003 , Pages 87-93 ; 0277027X (ISSN) ; Nayeb Hashemi, H ; Estekanchi, H. E ; ASME ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2003
Abstract
Cylindrical shells constitute the main structural components in pressure vessels and pipelines. Cylindrical shells made of fiber-reinforced composites are now being considered in the design of many components due to their high specific strength and stiffness. Buckling is one of the main failure considerations, when designing the cylindrical shells. The buckling behavior of the composite cylindrical shells can severely be compromised by introducing defect in the structure, due to high stress field generated around these defects. Defects could be generated during service due to cyclic loading or during manufacturing. A reliable operation of these structures require to understand the effects of...
Flexural behaviour of small steel fibre reinforced concrete slabs
, Article Cement and Concrete Composites ; Volume 27, Issue 1 , 2005 , Pages 141-149 ; 09589465 (ISSN) ; Afshari, M ; Sharif University of Technology
2005
Abstract
Influence of length and volumetric percentage of steel fibres on energy absorption of concrete slabs with various concrete strengths is investigated by testing 28 small steel fibre reinforced concrete (SFRC) slabs under flexure. Variables included; fibre length, volumetric percentage of fibres and concrete strength. Test results indicate that generally longer fibres and higher fibre content provide higher energy absorption. The results are compared with a theoretical prediction based on random distribution of fibres. The theoretical method resulted in higher energy absorption than that obtained in experiment. A design method according to allowable deflection is proposed for SFRC slabs within...
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...
Flexural behavior of concrete beams reinforced with high volume steel fibers
, Article ISEC 2013 - 7th International Structural Engineering and Construction Conference: New Developments in Structural Engineering and Construction ; 2013 , Pages 1031-1036 ; 9810753551 (ISBN) ; 9789810753559 (ISBN) ; Jahromi, H. S ; Mohammadian, A ; Yazdani S ; Singh A ; Sharif University of Technology
2013
Abstract
This paper presents the results of an experimental study on the flexural behavior of ten 10 × 15 × 120 (cm) steel reinforced high strength concrete beams under deflection control loading conditions. Test variable includes volumetric percentage of steel fibers (0%, 1.5%, 3%, 4%, 5%). The plain concrete strength was 30MPa. The monotonic concentrated load was applied at the center of the beam, the relative deflection was measured, and demec points were used to determine curvature of the beam. Load-deflection and moment-curvature diagrams have been obtained and plotted for each beam individually. Test results indicate that higher fiber content considerably improves flexural behavior and provides...
Mechanical properties of steel fiber-reinforced concrete slab tracks on non-ballasted foundations
, Article Scientia Iranica ; Volume 20, Issue 6 , 2013 , Pages 1626-1636 ; 10263098 (ISSN) ; Entezam, A ; Torki, M. E ; Sharif University of Technology
Sharif University of Technology
2013
Abstract
Mechanical properties of slab tracks on a foundation with nonlinear stiffness are accounted for. At first, the cracking stages were inspected in FEM models, and it was learned that slab tracks have one-way exural behavior. Secondly, experimental full-scale models were made, and the accuracy of analyses was verified by comparing the FEM loadde ection curves with those of previous studies and validating the cracking and ultimate loads with those obtained from experiments. Finally, the effects of several parameters on the cracking and ultimate loads and the energy absorption of steel fiber-reinforced slab tracks were investigated by examining the real behavior of slab tracks on elastic...
Use of polymer fibres recovered from waste car timing belts in high performance concrete
, Article Construction and Building Materials ; Volume 80 , April , 2015 , Pages 31-37 ; 09500618 (ISSN) ; Esrafili, A ; Kalani, M ; Mobini, M. H ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
The present paper discusses the possibility of adding recycled polymer fibres to high performance concrete (HPC). Fibres used in this study were recovered from discarded car timing belts. To investigate different characteristics of the concrete specimens several destructive and non-destructive tests, such as compressive strength, modulus of rupture, flexural toughness, ultrasonic velocity and electrical resistance tests were carried out. In addition, slump flow tests were conducted on the fresh concrete. Experimental results from the study showed that the use of low percentages (up to 0.5%) of waste fibres improved the modulus of rupture and flexural toughness. Based on ultrasonic and...
Fibrous and non-fibrous Perlite concretes – experimental and SEM studies
, Article European Journal of Environmental and Civil Engineering ; 2016 , Pages 1-27 ; 19648189 (ISSN) ; Eslami, E ; Anvari, A
Taylor and Francis Ltd
2016
Abstract
Mechanical properties and microstructural analysis of Expanded Perlite Aggregate (EPA) concretes are presented. Using 10% EPA, the effects of using various types of fibre were investigated. For all specimens, fibrous and non-fibrous, the compressive and the splitting tensile strengths were obtained. Complete stress–strain curves for fibre-reinforced specimens were obtained. A new index for representing the toughness of fibre-reinforced Perlite concretes is introduced. The addition of fibres substantially increased the splitting tensile strength. Steel fibres with “indentations” had the best performance in this regard. Regarding the toughness, specimens with “hooked” steel fibres performed...
Experimental investigation on effects of hybrid fibers on rheological, mechanical, and durability properties of high-strength SCC
, Article Construction and Building Materials ; Volume 147 , 2017 , Pages 497-509 ; 09500618 (ISSN) ; Khaloo, A ; Joshaghani, A ; Hajibandeh, E ; Sharif University of Technology
Abstract
The aim of the present study is to investigate the effects of using hybrid fibers on rheological, mechanical and durability properties of the high-strength self-consolidating concrete (SCC). For this purpose, two types of fibers including hooked-end steel fibers and polypropylene fibers were used. In this study, a total of eleven mixtures were used: one as a control mix, one containing 0.5% steel fibers, four containing 0.5% hybrid fibers (steel and polypropylene), one containing 1.0% steel fibers and the four containing 1.0% hybrid fibers (steel and polypropylene). For investigating the rheological properties, slump flow, J-ring and V-funnel tests were performed. Mechanical properties were...
Fibrous and non-fibrous Perlite concretes–experimental and SEM studies
, Article European Journal of Environmental and Civil Engineering ; Volume 22, Issue 2 , 2018 , Pages 138-164 ; 19648189 (ISSN) ; Eslami, E ; Anvari, A ; Sharif University of Technology
Taylor and Francis Ltd
2018
Abstract
Mechanical properties and microstructural analysis of Expanded Perlite Aggregate (EPA) concretes are presented. Using 10% EPA, the effects of using various types of fibre were investigated. For all specimens, fibrous and non-fibrous, the compressive and the splitting tensile strengths were obtained. Complete stress–strain curves for fibre-reinforced specimens were obtained. A new index for representing the toughness of fibre-reinforced Perlite concretes is introduced. The addition of fibres substantially increased the splitting tensile strength. Steel fibres with “indentations” had the best performance in this regard. Regarding the toughness, specimens with “hooked” steel fibres performed...
Advanced damage detection technique by integration of unsupervised clustering into acoustic emission
, Article Engineering Fracture Mechanics ; 2018 ; 00137944 (ISSN) ; Chai, H. K ; GhasemiGol, M ; Sepehrinezhad, A ; Mousa, A. A ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
The use of acoustic emission (AE) technique for damage diagnostic is typically challenging due to difficulties associated with discrimination of events that occur during different stages of damage that take place in a material or a structure. In this study, an unsupervised kernel fuzzy c-means pattern recognition analysis and the principal component method were utilized to categorize various damage stages in plain and steel fiber reinforced concrete specimens monitored by AE technique. Enhancement of the discrimination and characterization of damage mechanisms were achieved by processing time and frequency domain data. Both domains (time and frequency) were taken into account to propose new...
Assessment of plain and glass fiber-reinforced concrete under impact loading: a new approach via ultrasound evaluation
, Article Journal of Nondestructive Evaluation ; Volume 38, Issue 4 , 2019 ; 01959298 (ISSN) ; Toufigh, V ; Sharif University of Technology
Springer
2019
Abstract
Impact loading leads to micro-crack formation that can compromise the performance of the concrete. The purpose of this paper is to evaluate plain concrete and fiber-reinforced concrete specimens using ultrasound methods under impact loading. These specimens were prepared and subjected to impact loading. Ultrasound tests were performed at different stages of impact loading on each specimen. The loading continued until cracks on the surface of the specimens were observed. Investigations were performed for both plain concrete and fiber-reinforced concrete to establish a correlation between ultrasound response characteristics, and the damage caused by impact loading due to the energy of blows...
Advanced damage detection technique by integration of unsupervised clustering into acoustic emission
, Article Engineering Fracture Mechanics ; Volume 210 , 2019 , Pages 212-227 ; 00137944 (ISSN) ; Chai, H. K ; GhasemiGol, M ; Sepehrinezhad, A ; Mousa, A. A ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
The use of acoustic emission (AE) technique for damage diagnostic is typically challenging due to difficulties associated with discrimination of events that occur during different stages of damage that take place in a material or a structure. In this study, an unsupervised kernel fuzzy c-means pattern recognition analysis and the principal component method were utilized to categorize various damage stages in plain and steel fiber reinforced concrete specimens monitored by AE technique. Enhancement of the discrimination and characterization of damage mechanisms were achieved by processing time and frequency domain data. Both domains (time and frequency) were taken into account to propose new...
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) ; 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...
Experimental and numerical investigation of minimum required fiber content in bending characteristics of 100 MPa UHPC-formulated concrete
, Article Case Studies in Construction Materials ; Volume 16 , 2022 ; 22145095 (ISSN) ; Khaloo, A ; Hassanpour, S ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
The present study investigates the lowest possible amount of steel and polypropylene fibers in improving the compressive and flexural strength, stiffness, and energy capacity of high strength 100 MPa concrete with a mix design similar to that of Ultra-High Performance Concrete (UHPC). Twenty-eight 100 × 200 mm cylindrical specimens with 0%, 0.2%, 0.4%, and 0.6% volumetric percentage of short steel fibers and polypropylene fibers were fabricated, which were at the lowest predicted percentages with respect to fiber content recommended in the literature. To assess the flexural performance of fiber-reinforced concrete panels, specimens with dimensions of 200 × 600 × 20 mm were made with the same...
Determining shear capacity of ultra-high performance concrete beams by experiments and comparison with codes
, Article Scientia Iranica ; Volume 26, Issue 1A , 2019 , Pages 273-282 ; 10263098 (ISSN) ; Joghataie, A ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
In this research, 19 specimens of ultra-high performance fiber-reinforced concrete rectangular beams were made and their shear resistance was determined experimentally. The results were compared with estimations by ACI 318, RILEM TC 162-TDF, Australian guideline, and Iranian national building regulations. To compare the code estimations, the ratio of experimental shear strength to predicted shear strength was calculated for each code. This ratio is in fact a measure of safety factor on the one hand and a measure of precision of the estimation on the other hand. Based on the results of both studies, the authors concluded that the Australian guideline, with the amount of 2.5, provided the...
Determining shear capacity of ultra-high performance concrete beams by experiments and comparison with codes
, Article Scientia Iranica ; Volume 26, Issue 1A , 2019 , Pages 273-282 ; 10263098 (ISSN) ; Joghataie, A ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
In this research, 19 specimens of ultra-high performance fiber-reinforced concrete rectangular beams were made and their shear resistance was determined experimentally. The results were compared with estimations by ACI 318, RILEM TC 162-TDF, Australian guideline, and Iranian national building regulations. To compare the code estimations, the ratio of experimental shear strength to predicted shear strength was calculated for each code. This ratio is in fact a measure of safety factor on the one hand and a measure of precision of the estimation on the other hand. Based on the results of both studies, the authors concluded that the Australian guideline, with the amount of 2.5, provided the...
Performance of polypropylene fiber reinforced concrete-filled UPVC tube columns under axial compression
, Article Construction and Building Materials ; Volume 231 , 20 January , 2020 ; Khaloo, A ; Borhani, M. H ; Tale Masoule, M. S ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
This paper aims to study the behavior of UPVC-confined columns reinforced with polypropylene fibers under axial compression. A sum of 42 column specimens has been tested, including 18 Unconfined Concrete Cylinders (UCC) and 24 confined Concrete-Filled UPVC Tube (CFUT) specimens. To investigate the sensitivity of these columns to various parameters, different levels of material volumes have been used, which include two concrete strengths of 40 and 50 MPa, two tube grades of PN6 and PN10, and three polypropylene fiber content of 0, 1 and 3 kg/m3 of the concrete mixture. The influence of each variable on the ultimate strength, ductility and confinement effectiveness of the specimens have been...
Analytical modeling of strength in randomly oriented PP and PPTA short fiber reinforced gypsum composites
, Article Computational Materials Science ; Volume 50, Issue 5 , 2011 , Pages 1619-1624 ; 09270256 (ISSN) ; Sangghaleh, A ; Nazari, A ; Pourjavad, N ; Sharif University of Technology
Abstract
Fiber reinforced gypsum are prevalent building materials in which short fibers with high tensile strength are embedded into a gypsum matrix to produce supplemental strong and lightweight construction materials. Due to confrontation to a rising risk of death and economic disaster in earthquake-prone areas, quake-resistant materials and structures should be employed for building constructions. Gypsum based composites as a unique candidate for this purpose reduce the risks and produce much confident construction materials for residential buildings. In this work tensile strength of gypsum composites with different volume fraction of polypropylene (PP) and poly-paraphenylene terephthalamide...