The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
Temel Turker - One of the best experts on this subject based on the ideXlab platform.
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experimental and finite element analysis on the steel fiber reinforced Concrete sfrc beams ultimate behavior
Construction and Building Materials, 2009Co-Authors: Mehmet D Ozcan, Alemdar Bayraktar, Abdurrahman şahin, Tefaruk Haktanir, Temel TurkerAbstract:Abstract Steel fiber-added reinforced Concrete (SFRC) applications have become widespread in areas such as higher upper layers, tunnel shells, Concrete sewer pipes, and slabs of large industrial buildings. Usage of SFRC in load-carrying members of buildings having conventional reinforced Concrete (RC) frames is also gaining popularity recently because of its positive contribution to both energy absorption capacity and Concrete strength. This paper presents experimental and finite element analysis of three SFRC beams. For this purpose, three SFRC beams with 250 × 350 × 2000 mm dimensions are produced using a Concrete Class of C20 with 30 kg/m 3 dosage of steel fibers and steel Class S420 with shear stirrups. SFRC beams are subjected to bending by a four-point loading setup in certified beam-loading frame, exactly after having been moist-cured for 28 days. The tests are with control of loads. The beams are loaded until they are broken and the loadings are stopped when the tensile steel bars are broken into two pieces. Applied loads and mid-section deflections are carefully recorded at every 5 kN load increment from the beginning till the ultimate failure. One of the SFRC beams modeled by using nonlinear material properties adopted from experimental study is analyzed till the ultimate failure cracks by ANSYS. Eight-noded solid brick elements are used to model the Concrete. Internal reinforcement is modeled by using 3D spar elements. A quarter of the full beam is taken into account in the modeling process. The results obtained from the finite element and experimental analyses are compared to each other. It is seen from the results that the finite element failure behavior indicates a good agreement with the experimental failure behavior.
Y Ribakov - One of the best experts on this subject based on the ideXlab platform.
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a new concept for design of fibered high strength reinforced Concrete elements using ultimate limit state method
Materials & Design, 2013Co-Authors: Iakov Iskhakov, Y RibakovAbstract:Abstract Existing methods for design of reinforced Concrete (RC) bending elements in the ultimate limit state are based on calculating the compressed zone depth of the section. At the same time, in isotropic materials the neutral axis of the bending section crosses its center of gravity (CG). It was proved that if a neutral axis of bending RC element crosses the section’s CG, the total reinforcement section ( A s + A s ′ ) is minimal. Therefore the compressed zone depth should be selected so that under the design load the neutral axis should pass through the section’s CG. In this case the compressed zone depth that is unknown in existing design methods becomes a known value. This concept enables to select other parameters as unknowns (bending element Concrete Class, section height, etc.). It is especially important for design of modern high strength Concrete (HSC) bending elements, for which the Concrete Class can be calculated, but not selected. It is demonstrated that applying the proposed concept enables to assume that the neutral axis location is constant for all stages of stress - strain state in bending. As HSC is rather brittle, stresses diagram in the compressed section zone has a form close to triangular. However, adding steel fibers allows improving the elastic–plastic properties of HSC. In this case a rectangular stresses diagram can be used, as for normal strength Concrete. Consequently, the proposed concept yields more economical solutions and allows more effective using the HSC properties.
Mehmet D Ozcan - One of the best experts on this subject based on the ideXlab platform.
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experimental and finite element analysis on the steel fiber reinforced Concrete sfrc beams ultimate behavior
Construction and Building Materials, 2009Co-Authors: Mehmet D Ozcan, Alemdar Bayraktar, Abdurrahman şahin, Tefaruk Haktanir, Temel TurkerAbstract:Abstract Steel fiber-added reinforced Concrete (SFRC) applications have become widespread in areas such as higher upper layers, tunnel shells, Concrete sewer pipes, and slabs of large industrial buildings. Usage of SFRC in load-carrying members of buildings having conventional reinforced Concrete (RC) frames is also gaining popularity recently because of its positive contribution to both energy absorption capacity and Concrete strength. This paper presents experimental and finite element analysis of three SFRC beams. For this purpose, three SFRC beams with 250 × 350 × 2000 mm dimensions are produced using a Concrete Class of C20 with 30 kg/m 3 dosage of steel fibers and steel Class S420 with shear stirrups. SFRC beams are subjected to bending by a four-point loading setup in certified beam-loading frame, exactly after having been moist-cured for 28 days. The tests are with control of loads. The beams are loaded until they are broken and the loadings are stopped when the tensile steel bars are broken into two pieces. Applied loads and mid-section deflections are carefully recorded at every 5 kN load increment from the beginning till the ultimate failure. One of the SFRC beams modeled by using nonlinear material properties adopted from experimental study is analyzed till the ultimate failure cracks by ANSYS. Eight-noded solid brick elements are used to model the Concrete. Internal reinforcement is modeled by using 3D spar elements. A quarter of the full beam is taken into account in the modeling process. The results obtained from the finite element and experimental analyses are compared to each other. It is seen from the results that the finite element failure behavior indicates a good agreement with the experimental failure behavior.
Laurent Molez - One of the best experts on this subject based on the ideXlab platform.
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Mechanical and durability properties of Concrete based on recycled coarse and fine aggregates produced from demolished Concrete
Construction and Building Materials, 2020Co-Authors: Layachi Berredjem, Nourredine Arabi, Laurent MolezAbstract:Faced with aggressive environments, the durability of recycled aggregate Concretes constitutes one of the most unknown aspects. The employment opportunities of recycled Concrete aggregates will inevitably remain cautious due to the absence of well-established performance criteria. This paper is to investigate the influence of different granular compositions (recycled coarse and fine aggregate) on the mechanical characteristics and durability of Concrete. Five series of Concrete mixes, manufactured with various granular combinations (natural/recycled), were studied The formulation of the reference Concrete was based on a constant quantity of 400 kg/m3of cement and a constant workability of fresh Concrete securing S2 Class of flowability and C25/30 Concrete Class, according to European standards.The experimental program consisted of comparing the long-term mechanical strength of Concrete conserved in different types of water baths: fresh tap water sourced directly from the supply network, deionized water, and salt water. Also, the durability indicators were observed, such as capillary water absorption, porosity accessible to water, helium gas permeability, and an ammonium nitrate leaching test.The obtained results have highlighted the superiority of Concrete composed of natural aggregate over Concrete incorporating recycled aggregate for mechanical behaviour, case-observed with three types of water used as a conservation bath. The replacement of natural aggregate by recycled aggregate does not provide any substantial improvement in terms of durability. The use of recycled sand in Concrete increases its porosity and vulnerability to an aggressive environment.
Tamer Dirikgil - One of the best experts on this subject based on the ideXlab platform.
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Experimental investigation of mechanical properties of hybrid fiber reinforced Concrete samples and prediction of energy absorption capacity of beams by fuzzy-genetic model
Construction and Building Materials, 2013Co-Authors: Fatih Altun, Fevzi Tanrıöven, Tamer DirikgilAbstract:Abstract There have been a great number of studies aiming to improve the mechanical qualities of Concrete material which is a basic component of reinforced Concrete bearing systems. Attempts to reinforce the Concrete through fiber addition have an important place among these studies. This study is an experimental research on the mechanical features of hybrid fiber added Concretes which are obtained using steel fibers and polypropylene (PP) fibers together in certain proportions. Test specimens consist of 180 cylindrical samples (150 × 300 mm) and 90 prismatic (150 × 150 × 750 mm) beams produced in C40 Concrete Class. The specimens were exposed to temperatures ranging from room temperature to 100, 200, 400, 600 and 800 °C in a certain order following their cure periods of 7, 28 and 90 days. It was observed that hybrid fiber addition has a significant contribution into the compressive strength, flexural strength and energy absorption capacity of the Concrete. Significance of hybrid fiber addition was put forward for the increase in ductility of the Concrete which displays a brittle behavior when forced to bending. In the experimental studies with a numerous test specimens, losing of data due to some reasons and being unable to receive data was considered as a problem to be solved. Therefore, a fuzzy-genetic model was suggested to predict not only the experimental gaps, but also the untested value ranges of experimental parameters. Model was taken consideration in three different applications and it showed a satisfactory performance in predicting data.