scholarly journals Empirical equation and experimental validation of shear parameters for high strength concrete (HSC)

2021 ◽  
Vol 7 (2) ◽  
Author(s):  
Brijesh Singh ◽  
P N Ojha ◽  
Vikas Patel ◽  
Amit Trivedi ◽  
Abhishek Singh
Keyword(s):  
High Strength Concrete ◽  
High Strength ◽  
International Standards ◽  
Experimental Results ◽  
Efficient Estimation ◽  
Proper Understanding ◽  
Strength Concrete ◽  
Brittle Behavior ◽  
Sudden Failure ◽  
Dowel Action

With many benefits of the High Strength Concrete (HSC) the more brittle behavior which leads to sudden failure makes it important for proper understanding of its behaviour and safe and efficient estimation of capacities. Research on the behavior of HSC has been extensively carried out since last decade. High strength concrete has higher tensile strength hence a higher cracking shear can be expected. This paper analyses the different international standards available for estimating concrete’s component of shear strength for RCC beam. Different important factors mainly strength in compression, steel reinforcement (dowel action), ratio of shear span and depth, size effect i.e. depth along with the aggregate type (density of concrete) contributing to shear stress (Tc) of concrete has been also analyzed and thereafter, an equation has been proposed to compute or predict Tc value for concrete of both normal and higher grade or strength. The proposed equation has been validated by experimental results wherein 12 RCC beams (with and without reinforcement for shear) were cast and tested to fail in shear. The experimental results validated the proposed equation with considerable factor of safety keeping in view the sudden and brittle nature of failure in concrete in case of shear.

scholarly journals Empirical equation and experimental validation of shear parameters for high strength concrete (HSC)

2021 ◽  
Vol 7 (2) ◽  
pp. 46-55
Author(s):  
Brijesh Singh ◽  
◽  
P N Ojha ◽  
Vikas Patel ◽  
Amit Trivedi ◽  
...  
Keyword(s):  
High Strength Concrete ◽  
High Strength ◽  
International Standards ◽  
Experimental Results ◽  
Efficient Estimation ◽  
Proper Understanding ◽  
Strength Concrete ◽  
Sudden Failure ◽  
Dowel Action ◽  
Reinforced Cement

With many benefits of the high strength concrete (HSC) the more brittle behaviour that leads to sudden failure makes it important for proper understanding of its behaviour and safe and efficient estimation of capacities. Research on the behaviour of HSC has been extensively carried out since last decade. HSC has higher tensile strength hence a higher cracking shear can be expected. This paper analyzes the different international standards available for estimating concrete’s component of shear strength for reinforced cement concrete (RCC) beam. Different important factors mainly strength in compression, steel reinforcement (dowel action), ratio of shear span and depth, size effect i.e. depth along with the aggregate type (density of concrete) contributing to shear stress (Tc) of concrete has been also analyzed and thereafter, an equation has been proposed to compute or predict Tc value for concrete of both normal and higher grade or strength. The proposed equation has been validated by experimental results wherein 12 RCC beams (with and without reinforcement for shear) were cast and tested to fail in shear. The experimental results validated the proposed equation with considerable factor of safety keeping in view the sudden and brittle nature of failure in concrete in case of shear.

scholarly journals The bond stress x slipping relationship

2016 ◽  
Vol 9 (5) ◽  
pp. 745-753 ◽  
Author(s):  
M. T. G. BARBOSA ◽  
E. S. SÁNCHEZ FILHO
Keyword(s):  
Experimental Study ◽  
Statistical Analysis ◽  
High Strength Concrete ◽  
High Strength ◽  
Bond Stress ◽  
International Standards ◽  
Experimental Results ◽  
Strength Concrete ◽  
Pull Out ◽  
Steel Bar

Abstract A few international standards regulate the use of the high strength concrete, which may not be adopted generally without consideration of the differences that can be among the materials in different countries. This paper presents the results of an experimental study consisting of pull out tests of Brazilian steel, with five different concrete strengths, 20, 40, 60, 80 and 100 MPa, and three different steel bar diameters, 16.0, 20.0 and 25.0 mm. The experimental results for the bond stress vs. slipping relationship were compared with the provisions of the CEB and with some theoretical formulations found in literature. One statistical analysis is made and equations for predicting the bond stress were derived.

scholarly journals HIGH-STRENGTH CONCRETE HOLLOW BEAMS STRENGTHENED WITH EXTERNAL TRANSVERSAL STEEL REINFORCEMENT UNDER TORSION / SUKTINĖS STIPRIOJO BETONO DĖŽINIO SKERSPJŪVIO SIJOS, SUSTIPRINTOS IŠORINE PLIENINE SKERSINE ARMATŪRA

2011 ◽  
Vol 17 (3) ◽  
pp. 330-339 ◽  
Author(s):  
Luis F. A. Bernardo ◽  
Sergio M. R. Lopes
Keyword(s):  
High Strength Concrete ◽  
High Strength ◽  
Steel Reinforcement ◽  
Experimental Results ◽  
Pure Torsion ◽  
Strength Concrete ◽  
Box Beam ◽  
Torsion Moment ◽  
Hollow Beams ◽  
Transversal Reinforcement

Some bridges have to withstand high levels of torsion forces. As a consequence, box type beams are often the obvious solution. It could be possible that the balance of transversal to longitudinal torsion reinforcement is not fully reached. If the transversal reinforcement is somehow underestimated, the box beam needs to be transversally strengthened. From the various solutions, external transversal reinforcement is certainly one possibility. The investigation presented here aimed to study such solution. The authors tested four hollow beams under pure torsion. The level of the non balanced ratio between internal longitudinal and transversal torsion reinforcement was one of the parameters that were considered in this investigation. Other parameter was the existence or the no existence of external transversal strengthening reinforcement. The experimental results of the tests have shown the effectiveness of the use of the external transversal strengthening steel reinforcement to compensate the lack of balance of internal transversal to longitudinal torsion reinforcement with respect to various behaviour aspects, such as: increasing of torque strength, increasing of ductility, increasing of cracking torsion moment, and better distribution of cracking. Santrauka Kai kurie tiltai turi atlaikyti dideles sukimo jėgas. Tam tikslui dažnai naudojamos dėžinio skerspjūvio sijos. Gali būti, kad tarp sukimui atlaikyti naudojamos skersinės ir išilginės armatūros ne visada pasiekiamas tinkamas balansas. Jei skersinė sija armuota nepakankamai, dėžinio skerspjūvio sijas gali tekti papildomai stiprinti. Vienas iš įvairių galimų stiprinimo variantų – armavimas išorine skersine armatūra. Šiame straipsnyje pateikiama tokio stiprinimo analizė. Autoriai išbandė keturias grynojo sukimo veikiamas dėžinio skerspjūvio sijas. Vienas iš tyrimo parametrų – skersinės ir išilginės sukimo armatūrų santykio nesubalansuotumo lygis. Kitas parametras – išorinės skersinės stiprinimo armatūros buvimas arba nebuvimas. Eksperimentinių tyrimų rezultatai parodė stiprinti naudojamos išorinės plieninės skersinės armatūros veiksmingumą, kompensuojant vidinės skersinės ir išilginės suktinės armatūrų tarpusavio nesubalansuotumą. Efektyvumas buvo įrodytas tokias aspektais: padidėjusi sukamoji galia ir elastingumas, padidėjęs plyšių atsiradimo sukimo momentas bei geresnis plyšių pasiskirstymas.

scholarly journals Transverse Deformations and Structural Phenomenon as Indicators of Steel Fibred High-Strength Concrete Nonlinear Behavior

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Iakov Iskhakov ◽  
Yuri Ribakov
Keyword(s):  
High Strength Concrete ◽  
High Efficiency ◽  
Limit State ◽  
Nonlinear Behavior ◽  
High Strength ◽  
Steel Fibers ◽  
Ultimate Limit State ◽  
Strength Concrete ◽  
Brittle Behavior ◽  
Ductile Behavior

As known, high-strength compressed concrete elements have brittle behavior, and elastic-plastic deformations do not appear practically up to their ultimate limit state (ULS). This problem is solved in modern practice by adding fibers that allow development of nonlinear deformations in such elements. As a rule, are applied steel fibers that proved high efficiency and contribute ductile behavior of compressed high-strength concrete (HSC) elements as well as the desired effect at long-term loading (for other types of fibers, the second problem is still not enough investigated). However, accurate prediction of the ULS for abovementioned compression elements is still very important and current. With this aim, it is proposed to use transverse deformations in HSC to analyze compression elements' behavior at stages close to ultimate. It is shown that, until the appearance of nonlinear transverse deformations (cracks formation), these deformations are about 5-6 times lower than the longitudinal ones. When cracks appear, the tensile stress-strain relationship in the transverse direction becomes nonlinear. This fact enables to predict that the longitudinal deformations approach the ultimate value. Laboratory tests were carried out on 21 cylindrical HSC specimens with various steel fibers content (0, 20, 30, 40, and 60 kg/m3). As a result, dependences of transverse deformations on longitudinal ones were obtained. These dependences previously proposed by the authors’ concept of the structural phenomenon allow proper estimation of the compressed HSC state up to failure. Good agreement between experimental and theoretical results forms a basis for further development of modern steel fibered HSC theory and first of all nonlinear behavior of HSC.

scholarly journals Numeric Analysis on Shear Behavior of High-Strength Concrete Single-Keyed Dry Joints with Fixing Imperfections in Precast Concrete Segmental Bridges

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2914 ◽  
Author(s):  
Haibo Jiang ◽  
Mingzhu Chen ◽  
Zhijun Sha ◽  
Jie Xiao ◽  
Jiahui Feng
Keyword(s):  
Shear Strength ◽  
High Strength Concrete ◽  
Precast Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Lower Surface ◽  
Shear Capacity ◽  
Experimental Results ◽  
Strength Concrete ◽  
Segmental Bridges

Fixing imperfections in keyed dry joints between the concrete segments compromise the performance of precast concrete segmental bridges (PCSBs), which needs to consider carefully. In this study, a finite-element model on high-strength concrete single-keyed dry joints in PCSBs was established and validated by experimental results. Parametric studies on fixing imperfections in key, concrete strengths, and confining pressures were carried out based on that model. The numeric results included crack patterns, load–displacements and shear strength. Fixing imperfections—especially at lower surface of keys—reduced shear strength of single-keyed dry joints by the different shear transfer mechanism. Higher confining pressure and concrete strength improved the shear strength, but they mitigated and aggravated the effect of fixing imperfections at lower surface of key on shear strength, respectively. Compared with simulating results, AASHTO standard overestimated the shear capacity of single-keyed dry joints with fixing imperfections at lower surface of key by up to 0.602–22.0%, but greatly underestimated that of the rest. A modified formula with a strength reduction factor was proposed. For six experimental three-keyed dry-joint specimens and 30 numeric single-keyed dry-joint specimens with or without fixing imperfections, the average ratio of code predictions to experimental results was 90.4% and 81.6%, respectively.

Behavior of Steel Tube and Confined High Strength Concrete for Concrete-Filled RHS Tubes

2005 ◽  
Vol 8 (2) ◽  
pp. 101-116 ◽  
Author(s):  
Sumei Zhang ◽  
Lanhui Guo ◽  
Zaili Ye ◽  
Yuyin Wang
Keyword(s):  
High Strength Concrete ◽  
Concrete Strength ◽  
Compressive Load ◽  
High Strength ◽  
Steel Tube ◽  
Experimental Results ◽  
Stress Strain ◽  
Hollow Section ◽  
Strength Concrete ◽  
Nonlinear Stress

This paper presents an experimental study of the separated behavior of short ( L/H=3) high strength concrete-filled rectangular hollow section (RHS) tubes concentrically loaded in compression to failure. A total of 50 specimens were tested. Experimental results showed that the concrete strength influenced the failure pattern of the specimen. The height-to-breadth ratio of the rectangular tube (varying from 1.0 to 1.6) had no evident influence on the ultimate bearing capacity of the specimen. Then based on the experimental results, a numerical separation method was successfully used to separate the compressive load carried by the steel tube and the core concrete. The equivalent One-Dimensional nonlinear stress-strain models of the steel and the confined concrete were suggested, which can be used to determine the overall behavior of the high strength concrete-filled RHS tubes. The stress-strain models have been used to numerically analyze the behavior of high strength concrete-filled RHS tubes. The numerical results are compared with the experimental results and they agreed well with each other.

scholarly journals Structural Behavior of High-Strength Concrete Slabs Reinforced with GFRP Bars

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2997
Author(s):  
Maher A. Adam ◽  
Abeer M. Erfan ◽  
Fatma A. Habib ◽  
Taha A. El-Sayed
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
High Strength Concrete ◽  
High Strength ◽  
Element Model ◽  
Experimental Results ◽  
Structural Behavior ◽  
Concrete Slabs ◽  
Strength Concrete ◽  
Gfrp Bars

In this manuscript, structural testing was conducted on high-strength concrete slab specimens to investigate the behavior of such specimens when reinforced with a locally produced GFRP reinforcement. Subsequently, a finite element model (FEM) was constructed and validated against the experimental results. In the experimental phase, a total of eleven specimens (nine were reinforced with GFRP, while two were reinforced with conventional steel) were constructed and tested. The slabs dimensions are 700 mm × 1750 mm with variable thickness from 100 mm to 150 mm and different reinforcement ratios using different diameters. The structural behavior of the tested slabs was investigated in terms of ultimate load, ultimate deflection, load–deflection relationship, and crack pattern. Additionally, a nonlinear finite element model using the software ANSYS 2019-R1 was constructed to simulate the structural behavior of slabs reinforced with GFRP bars. The results obtained from the finite element analysis are compared with experimental results. The outcomes showed that the contribution of GFRP rebars in concrete slabs improved slab ductility and exhibited higher deflection when compared with traditional steel rebars. Good agreement between experimental and nonlinear analysis was obtained.

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