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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, 2016
    Co-Authors: Doo-yeol Yoo, Young Soo Yoon
    Abstract:

    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.

  • Nonlinear finite element analysis of ultra-High-Performance Fiber-reinforced concrete beams:
    International Journal of Damage Mechanics, 2015
    Co-Authors: Su-tae Kang, Nemkumar Banthia, Young Soo Yoon
    Abstract:

    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.

  • local bond slip response of gfrp rebar in ultra High Performance Fiber reinforced concrete
    Composite Structures, 2015
    Co-Authors: Doo-yeol Yoo, Jung Jun Park, Ki Yeon Kwon, Young Soo Yoon
    Abstract:

    Abstract This study investigates the bond Performance of steel and glass Fiber-reinforced polymer (GFRP) rebars embedded in ultra-High-Performance Fiber-reinforced concrete (UHPFRC). The steel rebar showed 2.8–3.6 times Higher bond strengths than the GFRP rebar and rebar yielding at embedment length of 2 times the rebar diameter. The bond failure of GFRP rebar occurred by delaminating resin and Fiber in GFRP rebar, different to that of steel rebar (shearing off and crushing of concrete). For GFRP rebar, Higher bond strength was obtained when a larger rebar diameter and a shorter embedment length were used, and reincrease of pull-out stress in softening branch was observed owing to wedging effect. Equations for normalized bond strength and development length of GFRP rebar embedded in UHPFRC with pull-out failure were suggested. In addition, analytical models for bond-slip response of GFRP rebar proposed in the literature were considered, and adequate parameters were derived from the present test data.

  • material and bond properties of ultra High Performance Fiber reinforced concrete with micro steel Fibers
    Composites Part B-engineering, 2014
    Co-Authors: Hyun-oh Shin, Jun-mo Yang, Young Soo Yoon
    Abstract:

    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, 2013
    Co-Authors: Young Soo Yoon
    Abstract:

    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.

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, 2018
    Co-Authors: Matthew J. Bandelt, Sarah L. Billington
    Abstract:

    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, 2016
    Co-Authors: Matthew J. Bandelt, Sarah L. Billington
    Abstract:

    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, 2014
    Co-Authors: Daniel M Moreno, William Trono, Claudia P Ostertag, Sarah L. Billington
    Abstract:

    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, 2007
    Co-Authors: Jon M Rouse, Sarah L. Billington
    Abstract:

    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.

Eugen Brühwiler - One of the best experts on this subject based on the ideXlab platform.

  • permeability of ultra High Performance Fiber reinforced concretes uhpfrc under High stresses
    Materials and Structures, 2007
    Co-Authors: Jeanphilippe Charron, E Denarie, Eugen Brühwiler
    Abstract:

    Ultra High Performance Fiber Reinforced Concretes (UHPFRC) present outstanding mechanical properties and a very low permeability which make them very attractive for the rehabilitation of existing structures and for new conceptions. UHPFRC are characterized by a significant tensile strain hardening (multiple cracking stage) that can be used to optimize the mechanical Performance of composite structural elements. In order to validate this assumption, permeability tests were carried out on UHPFRC specimens previously submitted to various levels of tensile deformation with progressive damage. Based on permeability results, it was possible to define maximal tensile deformations whereby the water permeability of a specific UHPFRC remains low for various exposure conditions.

  • experimental investigation of composite ultra High Performance Fiber reinforced concrete and conventional concrete members
    Aci Structural Journal, 2007
    Co-Authors: Kai Habel, E Denarie, Eugen Brühwiler
    Abstract:

    Composite ultra-High-Performance Fiber-reinforced concrete (UHPFRC) and conventional reinforced concrete structural members are investigated to assess the rehabilitation potential for existing concrete structures. The composite structural response is determined by testing 12 full-sized flexural beams, loading the UHPFRC layer in tension. The results demonstrate that the exceptional material properties of UHPFRC significantly improve the composite member structural response, including the ultimate force, stiffness, and cracking behavior. An analytical model is developed to predict the composite UHPFRC and conventional reinforced concrete structural response, and is employed to further analyze the experimental test results.

  • development of the mechanical properties of an ultra High Performance Fiber reinforced concrete uhpfrc
    Cement and Concrete Research, 2006
    Co-Authors: Kai Habel, Marco Viviani, E Denarie, Eugen Brühwiler
    Abstract:

    Knowledge of the mechanical properties, i.e. strength, stiffness and deformation capacity, of cementitious materials at any arbitrary time is fundamental for operations such as removal of formwork, prestressing or cracking control. This paper presents a study of the evolution of indexes related to hydration and their correlation to the development of the mechanical properties for an Ultra-High Performance Fiber Reinforced Concrete (UHPFRC). The hydration kinetics was determined using semi-adiabatic heat of hydration tests, and the mechanical properties were investigated experimentally at several ages between 3 and 365 days and then described with models originally developed for conventional concretes. Models and experiments were in good agreement. Furthermore, it was observed that for the UHPFRC, the rate of development of mechanical properties was Highest for the secant modulus, followed by the compressive and then the tensile strength.

Kai Habel - One of the best experts on this subject based on the ideXlab platform.

  • response of ultra High Performance Fiber reinforced concrete uhpfrc to impact and static loading
    Cement & Concrete Composites, 2008
    Co-Authors: Kai Habel, Paul Gauvreau
    Abstract:

    Abstract This paper presents an experimental and analytical study of rate-dependent ultra-High Performance Fiber reinforced concrete (UHPFRC) behavior. UHPFRC three- and four-point bending response was determined on plates subjected to quasi-static loading. Drop weight tests were performed in order to apply dynamic three-point-bending loading to UHPFRC plates. In addition, uniaxial tensile tests were performed at different strain rates. A cross-sectional bending model related the uniaxial tensile behavior to the bending response with good agreement. The equivalent static response of the plate specimens in the drop weight tests was successfully determined with nonlinear mass–spring models. The results of this study show a significantly increased strength and fracture energy of the dynamically loaded plates when compared to quasi-static loading and confirm the validity of the analytical modeling.

  • experimental investigation of composite ultra High Performance Fiber reinforced concrete and conventional concrete members
    Aci Structural Journal, 2007
    Co-Authors: Kai Habel, E Denarie, Eugen Brühwiler
    Abstract:

    Composite ultra-High-Performance Fiber-reinforced concrete (UHPFRC) and conventional reinforced concrete structural members are investigated to assess the rehabilitation potential for existing concrete structures. The composite structural response is determined by testing 12 full-sized flexural beams, loading the UHPFRC layer in tension. The results demonstrate that the exceptional material properties of UHPFRC significantly improve the composite member structural response, including the ultimate force, stiffness, and cracking behavior. An analytical model is developed to predict the composite UHPFRC and conventional reinforced concrete structural response, and is employed to further analyze the experimental test results.

  • development of the mechanical properties of an ultra High Performance Fiber reinforced concrete uhpfrc
    Cement and Concrete Research, 2006
    Co-Authors: Kai Habel, Marco Viviani, E Denarie, Eugen Brühwiler
    Abstract:

    Knowledge of the mechanical properties, i.e. strength, stiffness and deformation capacity, of cementitious materials at any arbitrary time is fundamental for operations such as removal of formwork, prestressing or cracking control. This paper presents a study of the evolution of indexes related to hydration and their correlation to the development of the mechanical properties for an Ultra-High Performance Fiber Reinforced Concrete (UHPFRC). The hydration kinetics was determined using semi-adiabatic heat of hydration tests, and the mechanical properties were investigated experimentally at several ages between 3 and 365 days and then described with models originally developed for conventional concretes. Models and experiments were in good agreement. Furthermore, it was observed that for the UHPFRC, the rate of development of mechanical properties was Highest for the secant modulus, followed by the compressive and then the tensile strength.

Paolo Riva - One of the best experts on this subject based on the ideXlab platform.

  • Shear strengthening of reinforced concrete beam with High-Performance Fiber-reinforced cementitious composite jacketing
    Aci Structural Journal, 2014
    Co-Authors: Alberto Meda, Serena Mostosi, Paolo Riva
    Abstract:

    The possibility of using thin High-Performance jackets aimed at improving the structural and shear capacity of existing reinforced concrete members is investigated in this paper. The jackets are made of High-Performance Fiber-reinforced concrete, with a steel mesh fabric sometimes added (diameter of the wires = 2 mm [0.078 in.]; wire spacing = 25.4 mm [1 in.]; and ultimate strength of steel = 550 N/mm2 [79.8 ksi]). Two different High-Performance cementitious composites are investigated: a self-leveling concrete suitable for casting thin members, and a thixotropic concrete requiring no molds during casting operations. To assess the effectiveness of the proposed solutions, different jackets were used to reinforce short, simply supported reinforced concrete beams (2.85 m [9.35 ft] long) lacking stirrups. The beams were tested up to failure in four-point bending, and the numerous test results, including a close comparison with the reference un-strengthened beam, are presented and discussed. The experimental results demonstrate the effectiveness of the technique proposed. All strengthened beams reached their theoretical bending capacity, whereas the unreinforced beam failed in shear.

  • Column and Joint Retrofitting with High Performance Fiber Reinforced Concrete Jacketing
    Journal of Earthquake Engineering, 2011
    Co-Authors: Consuelo Beschi, Alberto Meda, Paolo Riva
    Abstract:

    A new technique for the strengthening of existing R.C. structures, based on the application of a High Performance Fiber reinforced concrete jacket, is investigated here. The aim of the research is to study the possibility of using this technique for the seismic retrofitting of existing columns and beam-column joints. Two full-scale tests have been performed: a column-to-foundation joint and a beam-column joint. The specimens have been loaded with static horizontal cyclic loads with increasing amplitude. The results show that with the adoption of this technique it is possible to significantly increase both bearing capacity and ductility of existing R.C. structures.

  • Beam-Column Joint Retrofitting with High Performance Fiber Reinforced Concrete Jacketing
    Applied Mechanics and Materials, 2011
    Co-Authors: Consuelo Beschi, Alberto Meda, Paolo Riva
    Abstract:

    The possibility of strengthening existing R/C structures with a new technique based on the application of a High Performance Fiber Reinforced Concrete jacket is investigated herein, with the aim of studying the effectiveness of this technique for seismic retrofitting. The results of a beam-column joint full scale test simulating the behavior of existing beam-column joints are presented. The specimen have been subjected first to static loads and after to cyclic actions with increasing amplitude, up to failure. The tests demonstrated that, with the application of a HPFRC jacket, it was possible to remarkably increase the bearing capacity of the columns reaching also an adequate level of ductility, and the resistance of the beam column joints, with very little visible damage, thanks to the tensile strength contribution of HPFRC.

  • High Performance Fiber Reinforced Concrete Jacketing in a Seismic Retrofitting Application
    Improving the Seismic Performance of Existing Buildings and Other Structures, 2009
    Co-Authors: Consuelo Beschi, Alberto Meda, Paolo Riva
    Abstract:

    A new technique for the strengthening of existing R.C. structures, based on the application of a High Performance Fiber reinforced jacket, is investigated herein. Aim of the research is to study the possibility of using this technique for the seismic retrofitting of existing columns. A full scale test has been performed on a column-foundation element. The specimen has been loaded with static cyclic action having increasing amplitude, up to failure. The results shows that with the adoption of this technique it is possible to significantly increase both bearing capacity and ductility of the existing R.C. structure.