The Experts below are selected from a list of 5505 Experts worldwide ranked by ideXlab platform
Young-soo Yoon - One of the best experts on this subject based on the ideXlab platform.
-
A Review on Structural Behavior, Design, and Application of Ultra-High-Performance Fiber-Reinforced Concrete
International Journal of Concrete Structures and Materials, 2016Co-Authors: Doo-yeol Yoo, Young-soo YoonAbstract:An overall review of the structural behaviors of ultra-high-Performance Fiber-reinforced concrete (UHPFRC) elements subjected to various loading conditions needs to be conducted to prevent duplicate research and to promote its practical applications. Thus, in this study, the behavior of various UHPFRC structures under different loading conditions, such as flexure, shear, torsion, and high-rate loads (impacts and blasts), were synthetically reviewed. In addition, the bond Performance between UHPFRC and reinforcements, which is fundamental information for the structural Performance of reinforced concrete structures, was investigated. The most widely used international recommendations for structural design with UHPFRC throughout the world (AFGC-SETRA and JSCE) were specifically introduced in terms of material models and flexural and shear design. Lastly, examples of practical applications of UHPFRC for both architectural and civil structures were examined.
-
flexural behavior of ultra high Performance Fiber reinforced concrete beams reinforced with gfrp and steel rebars
Engineering Structures, 2016Co-Authors: Nemkumar Banthia, Young-soo YoonAbstract:Abstract This study describes the flexural behavior of ultra-high-Performance Fiber-reinforced concrete (UHPFRC) beams reinforced with glass Fiber-reinforced polymer (GFRP) rebars and hybrid reinforcements (steel + GFRP rebars). Three GFRP bar-reinforced beams and four hybrid reinforced beams with different reinforcement ratios were fabricated and tested. Owing to the strain-hardening characteristics of UHPFRC, all test beams exhibited very stiff load–deflection behavior after the formation of cracks and satisfied the service crack width criteria of CAN/CSA S806. In addition, deformability factors higher than the lower limit of CAN/CSA-S6 were obtained for all test beams. The increase in the reinforcement ratio of GFRP rebars resulted in the improvement of their flexural Performances, including post-cracking stiffness, load carrying capacity, and ductility (or deformability). The use of hybrid reinforcements by replacing a part of a GFRP rebar with a steel rebar contributed to a higher post-cracking stiffness before steel yielding, but led to lower deformability. Based on a sectional analysis, both AFGC/SETRA and JSCE recommendations were appropriate for predicting the moment–curvature response of UHPFRC beams with GFRP rebars and hybrid reinforcements: the average ratios of the maximum moments obtained from experiments and numerical analyses were found to be 1.12 and 0.94, respectively.
-
Nonlinear finite element analysis of ultra-high-Performance Fiber-reinforced concrete beams:
International Journal of Damage Mechanics, 2015Co-Authors: Su Tae Kang, Nemkumar Banthia, Young-soo YoonAbstract:A nonlinear finite element analysis was performed to simulate the flexural behaviors of ultra-high-Performance Fiber-reinforced concrete beams. For this, two different tension-softening curves obtained from micromechanics-based analysis and inverse analysis were incorporated. For micromechanics-based analysis, two-dimensional and three-dimensional random Fiber orientations were assumed to obtain the Fiber-bridging curve, and a softening curve of matrix in ultra-high-Performance Fiber-reinforced concrete was used. The use of tension-softening curves obtained from inverse analysis and micromechanics-based analysis using two-dimensional random Fiber orientation exhibited fairly good agreement with the experimental results, whereas the use of tension-softening curve from micromechanics-based analysis using three-dimensional random Fiber orientation underestimated the experimental results.
-
material and bond properties of ultra high Performance Fiber reinforced concrete with micro steel Fibers
Composites Part B-engineering, 2014Co-Authors: Hyun Oh Shin, Jun Mo Yang, Young-soo YoonAbstract:Abstract For investigating the effect of Fiber content on the material and interfacial bond properties of ultra high Performance Fiber reinforced concrete (UHPFRC), four different volume ratios of micro steel Fibers (Vf = 1%, 2%, 3%, and 4%) were used within an identical mortar matrix. Test results showed that 3% steel Fiber by volume yielded the best Performance in terms of compressive strength, elastic modulus, shrinkage behavior, and interfacial bond strength. These parameters improved as the Fiber content was increased up to 3 vol.%. Flexural behaviors such as flexural strength, deflection, and crack mouth opening displacement at peak load had pseudo-linear relationships with the Fiber content. Through inverse analysis, it was shown that fracture parameters including cohesive stress and fracture energy are significantly influenced by the Fiber content: higher cohesive stress and fracture energy were achieved with higher Fiber content. The analytical models for the ascending branch of bond stress-slip response suggested in the literature were considered for UHPFRC, and appropriate parameters were derived from the present test data.
-
effect of Fiber content on mechanical and fracture properties of ultra high Performance Fiber reinforced cementitious composites
Composite Structures, 2013Co-Authors: Young-soo YoonAbstract:Abstract This study investigated the mechanical properties of ultra high Performance Fiber reinforced cementitious composites (UHPFRCC) with four different Fiber volume fractions (Vf = 1%, 2%, 3%, and 4%) within an identical mortar matrix. The higher amount of Fiber resulted in an improvement of load carrying capacity and elastic modulus in compression up to 3 vol.% of Fibers. A higher pullout strength was obtained from the inclusion of Fibers in the matrix, and 2 vol.% of Fibers provided the best Performance in all aspects of Fiber pullout behavior including average and equivalent bond strengths and pullout energy. The flexural strength was pseudo-linearly increased with increase in Fiber volume fraction, despite an insignificant difference in the first cracking load. Furthermore, a bi-linear softening curve for UHPFRCC was suggested based on the result of inverse analysis, and it was verified through comparison with the experimental data.
Su Tae Kang - One of the best experts on this subject based on the ideXlab platform.
-
Nonlinear finite element analysis of ultra-high-Performance Fiber-reinforced concrete beams:
International Journal of Damage Mechanics, 2015Co-Authors: Su Tae Kang, Nemkumar Banthia, Young-soo YoonAbstract:A nonlinear finite element analysis was performed to simulate the flexural behaviors of ultra-high-Performance Fiber-reinforced concrete beams. For this, two different tension-softening curves obtained from micromechanics-based analysis and inverse analysis were incorporated. For micromechanics-based analysis, two-dimensional and three-dimensional random Fiber orientations were assumed to obtain the Fiber-bridging curve, and a softening curve of matrix in ultra-high-Performance Fiber-reinforced concrete was used. The use of tension-softening curves obtained from inverse analysis and micromechanics-based analysis using two-dimensional random Fiber orientation exhibited fairly good agreement with the experimental results, whereas the use of tension-softening curve from micromechanics-based analysis using three-dimensional random Fiber orientation underestimated the experimental results.
-
the relation between Fiber orientation and tensile behavior in an ultra high Performance Fiber reinforced cementitious composites uhpfrcc
Cement and Concrete Research, 2011Co-Authors: Su Tae KangAbstract:Abstract In this study, the effect of the Fiber orientation distribution on the tensile behavior of Ultra High Performance Fiber Reinforced Cementitious Composites (UHPFRCC) was investigated. The tensile behavior was explored separately in two stages; pre-cracking and post-cracking tensile behaviors. Pre-cracking tensile behavior is expressed using the mechanism of elastic shear transfer between the matrix and the Fiber in the composites. Post-cracking tensile behavior was expressed as the combined behavior of the resistance by the Fibers and the matrix, considering a probability density distribution for the Fiber orientation distribution across crack surface and a pullout model of steel Fiber. The effect of the Fiber orientation distribution was found to be very small on pre-cracking behavior, but to be significant on post-cracking behavior of UHPFRCC. The predicted results were compared with the experimental results, and the comparison presented satisfactory agreement.
-
tensile fracture properties of an ultra high Performance Fiber reinforced concrete uhpfrc with steel Fiber
Composite Structures, 2010Co-Authors: Su Tae Kang, Yondong ParkAbstract:This paper presents a study of the tensile fracture properties of Ultra High Performance Fiber Reinforced Concrete (UHPFRC) considering the effects of the Fiber content. To investigate the impact of Fiber content, notched 3-point bending tests were executed, where the Fiber volume ratio was varied from 0% to 5%. From the bending tests, it was found that the flexural tensile strength of UHPFRC linearly increases with increasing Fiber volume ratio and the rule of mixture can be applied to UHPFRC. Furthermore, an inverse analysis was performed to determine the tensile fracture model of UHPFRC and a tri-linear tensile softening model is suggested. The suggested model successfully represents the increase of the stress-constant bridging zone and the decrease of the stress-resisting zone with increasing Fiber content. The proposed model for various Fiber content levels is simple and versatile and can be readily applied to structural design or numerical analysis of UHPFRC.
Bassam A. Tayeh - One of the best experts on this subject based on the ideXlab platform.
-
mechanical and permeability properties of the interface between normal concrete substrate and ultra high Performance Fiber concrete overlay
Construction and Building Materials, 2012Co-Authors: Bassam A. Tayeh, B Abu H Bakar, Megat Azmi Megat JohariAbstract:Abstract As a rule of thumb, the interfacial bonding between deteriorated concrete structures with a newly overlay repair material is one of the most important factors for structural functionality and safety as well as durability Performance. In order to acquire an enhanced resistance against penetration of harmful substances, a good and effective bonding is necessary at the concrete interfaces. The objective of this study is to examine experimentally the mechanical properties and permeability characteristics of the interface between normal concrete (NC) substrate which represents old concrete structures and an overlay of ultra high Performance Fiber concrete (UHPFC) as a repair material. The mechanical interfacial bond characteristics were assessed using the slant shear and splitting tensile tests to quantify the influence of the differently roughened substrate surfaces. On the other hand, the permeability characteristics were evaluated by means of the rapid chloride permeability, gas and water permeability tests. The results show that the newly overlay UHPFC achieves high bond strength and bonds efficiently with the NC substrates. The specimens with sand blasted substrate surface give the best interfacial mechanical bonding in comparison to other types of surface preparation. The permeability tests proved that the interfacial bonding is very good and efficient which significantly improve the impermeability of the composites, and this was clearly shown by the SEM micrograph of the interface. Hence, it is envisaged that the use of UHPFC concomitant with appropriate surface preparation of the substrate should be able to provide effective and durable concrete repair.
-
Characterization of the interfacial bond between old concrete substrate and ultra high Performance Fiber concrete repair composite
Materials and Structures, 2012Co-Authors: Bassam A. Tayeh, B.h. Abu Bakar, Megat Azmi Megat JohariAbstract:The interfacial bond characteristics between normal concrete substrate as old concrete and ultra high Performance Fiber concrete as repair material have been investigated. Normal concrete substrates were first subjected to different surface preparation methods prior to bonding the ultra high Performance Fiber concrete to form repair composites. The interfacial mechanical bond of the composites was assessed using slant shear and tensile splitting strength tests. In addition, rapid chloride permeability test was performed to ascertain the potential chloride resistance of the composites. The microstructure of the transition zone between the normal concrete and ultra high Performance Fiber concrete was also studied using scanning electron microscope. The results generally indicate that surface preparation of the substrate is very much required to obtain superior mechanical bond of the composites; whereby the composites with the sand-blasted substrate providing the most superior mechanical bond. The excellent bond of the composite is also evident through the rapid chloride permeability test, as well as confirms by the scanning electron microscope image of the interface. Hence, the ultra high Performance Fiber concrete exhibits significant potential as an excellent material for repair and rehabilitation of concrete structures.
-
Mechanical and permeability properties of the interface between normal concrete substrate and ultra high Performance Fiber concrete overlay
Construction and Building Materials, 2012Co-Authors: Bassam A. Tayeh, B. H. Abu Bakar, M. A. Megat Johari, Yen Lei VooAbstract:As a rule of thumb, the interfacial bonding between deteriorated concrete structures with a newly overlay repair material is one of the most important factors for structural functionality and safety as well as durability Performance. In order to acquire an enhanced resistance against penetration of harmful substances, a good and effective bonding is necessary at the concrete interfaces. The objective of this study is to examine experimentally the mechanical properties and permeability characteristics of the interface between normal concrete (NC) substrate which represents old concrete structures and an overlay of ultra high Performance Fiber concrete (UHPFC) as a repair material. The mechanical interfacial bond characteristics were assessed using the slant shear and splitting tensile tests to quantify the influence of the differently roughened substrate surfaces. On the other hand, the permeability characteristics were evaluated by means of the rapid chloride permeability, gas and water permeability tests. The results show that the newly overlay UHPFC achieves high bond strength and bonds efficiently with the NC substrates. The specimens with sand blasted substrate surface give the best interfacial mechanical bonding in comparison to other types of surface preparation. The permeability tests proved that the interfacial bonding is very good and efficient which significantly improve the impermeability of the composites, and this was clearly shown by the SEM micrograph of the interface. Hence, it is envisaged that the use of UHPFC concomitant with appropriate surface preparation of the substrate should be able to provide effective and durable concrete repair. © 2012 Elsevier Ltd. All rights reserved.
Megat Azmi Megat Johari - One of the best experts on this subject based on the ideXlab platform.
-
evaluation of ultra high Performance Fiber reinforced concrete binder content using the response surface method
Materials & Design, 2013Co-Authors: M A A Aldahdooh, Muhamad N Bunnori, Megat Azmi Megat JohariAbstract:Abstract One of the major disadvantages in ultra-high-Performance-Fiber reinforced concrete (UHP-FRC) is its high ordinary Portland cement (OPC) content, which directly translates into an increase in OPC production. More OPC production results in increased emission of greenhouse gases, as well increased electrical energy consumption and concrete price. This study is aimed at adjusting the binder content (OPC and silica fume (SF) contents) of UHP-FRC using the response surface method. The present investigation shows that, for a given water/binder and superplasticizer/OPC, the compressive strength is independent of the binder content, whereas the flow depends on the binder content. Increasing the binder content does not enhance the strength compared with the required design strength because the capillary porosity increases with increasing OPC content; however, the workability increases. The final result is the production of a UHP-FRC with an OPC content of 720.49 kg/m 3 , an SF content of 214.25 kg/m 3 , a compressive strength of 181.41 MPa, a direct tensile strength of 12.49 MPa, a bending tensile strength of 30.31 MPa, and a flow of 167 mm.
-
mechanical and permeability properties of the interface between normal concrete substrate and ultra high Performance Fiber concrete overlay
Construction and Building Materials, 2012Co-Authors: Bassam A. Tayeh, B Abu H Bakar, Megat Azmi Megat JohariAbstract:Abstract As a rule of thumb, the interfacial bonding between deteriorated concrete structures with a newly overlay repair material is one of the most important factors for structural functionality and safety as well as durability Performance. In order to acquire an enhanced resistance against penetration of harmful substances, a good and effective bonding is necessary at the concrete interfaces. The objective of this study is to examine experimentally the mechanical properties and permeability characteristics of the interface between normal concrete (NC) substrate which represents old concrete structures and an overlay of ultra high Performance Fiber concrete (UHPFC) as a repair material. The mechanical interfacial bond characteristics were assessed using the slant shear and splitting tensile tests to quantify the influence of the differently roughened substrate surfaces. On the other hand, the permeability characteristics were evaluated by means of the rapid chloride permeability, gas and water permeability tests. The results show that the newly overlay UHPFC achieves high bond strength and bonds efficiently with the NC substrates. The specimens with sand blasted substrate surface give the best interfacial mechanical bonding in comparison to other types of surface preparation. The permeability tests proved that the interfacial bonding is very good and efficient which significantly improve the impermeability of the composites, and this was clearly shown by the SEM micrograph of the interface. Hence, it is envisaged that the use of UHPFC concomitant with appropriate surface preparation of the substrate should be able to provide effective and durable concrete repair.
-
Characterization of the interfacial bond between old concrete substrate and ultra high Performance Fiber concrete repair composite
Materials and Structures, 2012Co-Authors: Bassam A. Tayeh, B.h. Abu Bakar, Megat Azmi Megat JohariAbstract:The interfacial bond characteristics between normal concrete substrate as old concrete and ultra high Performance Fiber concrete as repair material have been investigated. Normal concrete substrates were first subjected to different surface preparation methods prior to bonding the ultra high Performance Fiber concrete to form repair composites. The interfacial mechanical bond of the composites was assessed using slant shear and tensile splitting strength tests. In addition, rapid chloride permeability test was performed to ascertain the potential chloride resistance of the composites. The microstructure of the transition zone between the normal concrete and ultra high Performance Fiber concrete was also studied using scanning electron microscope. The results generally indicate that surface preparation of the substrate is very much required to obtain superior mechanical bond of the composites; whereby the composites with the sand-blasted substrate providing the most superior mechanical bond. The excellent bond of the composite is also evident through the rapid chloride permeability test, as well as confirms by the scanning electron microscope image of the interface. Hence, the ultra high Performance Fiber concrete exhibits significant potential as an excellent material for repair and rehabilitation of concrete structures.
Sarah L. Billington - One of the best experts on this subject based on the ideXlab platform.
-
Simulation of Deformation Capacity in Reinforced High-Performance Fiber-Reinforced Cementitious Composite Flexural Members
Journal of Structural Engineering-asce, 2018Co-Authors: Matthew J. Bandelt, Sarah L. BillingtonAbstract:AbstractStrategies used to simulate the response of ductile cementitious materials, such as high-Performance Fiber-reinforced cementitious composites (HPFRCCs), have primarily focused on simulating...
-
Bond behavior of steel reinforcement in high-Performance Fiber-reinforced cementitious composite flexural members
Materials and Structures, 2016Co-Authors: Matthew J. Bandelt, Sarah L. BillingtonAbstract:High-Performance Fiber-reinforced cementitious composites (HPFRCCs) exhibit a pseudo strain hardening behavior in tension, and increased damage tolerance when loaded in compression. The unique properties of HPFRCC materials make them a viable material for increasing structural Performance under severe loading conditions. In this paper, the bond Performance of mild steel reinforcement embedded in HPFRCC beams is presented. Beam specimens with lap splices were tested in four-point bending to examine the bond strength and bond-slip behavior of steel reinforcement embedded in HPFRCC materials. Specimens made with three different HPFRCC mixtures, as well as a traditional normal weight concrete were tested in four point bending. The parameters investigated were the amount of concrete cover and the presence of steel confinement in the lap splice region. Experimental results show that HPFRCC normalized bond strengths increased by 37 %, on average, when compared to concrete. Furthermore, the bond-slip behavior of reinforcement in HPFRCCs had a higher toughness than observed for concrete specimens. Test results are compared with existing bond-slip models for Fiber reinforced concrete from beam tests and HPFRCCs from pullout experiments, and a recommendation to modify the ascending branch of an existing bond-slip model applicable to ductile HPFRCCs is proposed.
-
tension stiffening in reinforced high Performance Fiber reinforced cement based composites
Cement & Concrete Composites, 2014Co-Authors: Daniel M Moreno, William Trono, Claudia P Ostertag, Sarah L. BillingtonAbstract:Abstract High Performance Fiber-Reinforced Cement-based Composite (HPFRCC) materials carry tension to strains greater than the yield strain of reinforcing steel and exhibit distributed compression damage with minimal spalling. Characterization of the interaction between the composite and steel reinforcement to large strains (i.e., >0.005) remains largely unknown. Three HPFRCC materials as well as concrete with a single reinforcing bar are tested in a prismatic specimen in uniaxial tension up to fracture of the reinforcement. Multiple cracking of the composite led to uniform bar yielding throughout the specimen and early hardening of the reinforcement at the location of dominant cracks. The reinforcement fractured within the HPFRCC at lower strain levels relative to the reinforced concrete. A modified approach based on planar analysis to estimate flexural strength of reinforced HPFRCC components using tension-stiffening data is proposed.
-
Creep and shrinkage of high-Performance Fiber-reinforced cementitious composites
Aci Materials Journal, 2007Co-Authors: Jon M Rouse, Sarah L. BillingtonAbstract:The authors studied engineered cementitious composites (ECC), a class of high-Performance Fiber-reinforced cementitious composites, for its time-dependent properties. A pseudo strain-hardening response was exhibited by the material with multiple fine cracking in uniaxial tension. Information on creep recovery, drying creep, basic creep, and shrinkage of the material was obtained through a series of experiments on ECC specimens and similar Fiberless specimens. Established predictive concrete shrinkage and creep models were compared to the ECC data. Greater creep strain development occurred in ECC material than in a similar Fiber unreinforced cementitious mixture. Material shrinkage behavior estimates and shrinkage strain measurements were effected by surface cracking. While not developed for such material, a reasonable creep and shrinkage behavior estimate can be obtained through existing predictive models.