scholarly journals Experimental and Numerical Investigations on High Performance SFRC: Cyclic Tensile Loading and Fatigue

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7593
Author(s):  
Niklas Schäfer ◽  
Vladislav Gudžulić ◽  
Rolf Breitenbücher ◽  
Günther Meschke
Keyword(s):  
Numerical Simulations ◽  
High Performance ◽  
High Performance Concrete ◽  
Crack Opening ◽  
Hysteresis Loops ◽  
High Strength ◽  
Tensile Tests ◽  
Total Surface Area ◽  
Steel Fibers ◽  
Unloading Stiffness

In the present study, the capability of high-strength short steel fibers to control the degradation in high-performance concrete was experimentally examined and numerically simulated. To this end, notched prismatic high-performance concrete specimens with (HPSFRC) and without (HPC) short steel fibers were subjected to static and cyclic tensile tests up to 100,000 cycles. The cyclic tests showed that the rate of strain increase was lower for HPSFRC specimens and that the strain stagnated after around 10,000 cycles, which was not the case with HPC specimens. The microscopic examinations showed that in HPSFRC, a larger number of microcracks developed, but they had a smaller total surface area than the microcracks in the HPC. To further investigate the influence of fibers on the behavior of HPSFRC in the cracked state, displacement-controlled crack opening tests, as well as numerical simulations thereof, were carried out. Experiments have shown, and the numerical simulations have confirmed, that the inclusion of short steel fibers did not significantly affect the ultimate strength; however, it notably increased the post-cracking ductility of the material. Finally, the unloading/reloading behavior was examined, and it was observed that the unloading stiffness was stable even for significant crack openings; however, the hysteresis loops due to unloading/reloading were very small.

scholarly journals Resistance of an Optimized Ultra-High Performance Fiber Reinforced Concrete to Projectile Impact

Buildings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 63
Author(s):  
Anna L. Mina ◽  
Michael F. Petrou ◽  
Konstantinos G. Trezos
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Fiber Reinforced ◽  
Depth Of Penetration ◽  
Projectile Impact ◽  
High Performance Fiber

The scope of this paper is to investigate the performance of ultra-high performance fiber reinforced concrete (UHPFRC) concrete slabs, under projectile impact. Mixture performance under impact loading was examined using bullets with 7.62 mm diameter and initial velocity 800 m/s. The UHPFRC, used in this study, consists of a combination of steel fibers of two lengths: 6 mm and 13 mm with the same diameter of 0.16 mm. Six composition mixtures were tested, four UHPFRC, one ultra-high performance concrete (UHPC), without steel fibers, and high strength concrete (HSC). Slabs with thicknesses of 15, 30, 50, and 70 mm were produced and subjected to real shotgun fire in the field. Penetration depth, material volume loss, and crater diameter were measured and analyzed. The test results show that the mixture with a combination of 3% 6 mm and 3% of 13 mm length of steel fibers exhibited the best resistance to projectile impact and only the slabs with 15 mm thickness had perforation. Empirical models that predict the depth of penetration were compared with the experimental results. This material can be used as an overlay to buildings or to construct small precast structures.

Repair of Severely Damaged Reinforced Concrete Beams with High-Strength Cementitious Grout

2020 ◽  
Vol 2674 (6) ◽  
pp. 372-384
Author(s):  
Antoine N. Gergess ◽  
Mahfoud Shaikh Al Shabab ◽  
Razane Massouh
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Cementitious Materials ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Rc Structures

High-strength cementitious materials such as high-performance concrete are extensively used for retrofit of reinforced concrete (RC) structures. The effectiveness of these materials is increased when mixed with steel fibers. A commonly used technique for strengthening and repair of RC beams consists of applying high-performance fiber-reinforced concrete jackets around the beam perimeter. This paper investigates the jacketing method for repairing severely damaged RC beams. Four 2 m (6 ft 63/4 in.) long rectangular RC beams, 200 × 300 mm (8 ×12 in.) were initially cast and loaded until failure based on three-point bending tests. The four beams were then repaired by thickening the sides of the damaged RC beams using a commercially available high-strength shrinkage grout with and without steel fibers. Strain and deformation were recorded in the damaged and repaired beams to compare structural performance. It is shown that the flexural strength of the repaired beams is increased and the crack pattern under loading is improved, proving that the proposed repair method can restore the resistance capacity of RC beams despite the degree of damage. A method for repair is proposed and an analytical investigation is also performed to understand the structural behavior of the repaired beams based on different thickening configurations.

scholarly journals Effect of Hybridization of steel fibers on the mechanical properties of high strength concrete

2018 ◽  
Vol 199 ◽  
pp. 11006
Author(s):  
M. Iqbal Khan ◽  
Wasim Abbass
Keyword(s):  
Mechanical Properties ◽  
High Strength Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Research Work ◽  
High Strength ◽  
Steel Fibers ◽  
Flexural Properties ◽  
Strength Concrete ◽  
Total Percentage

The hybridization of fibers for arresting the crack in concrete is a key factor and play an important role to improve mechanical properties of high performance concrete with respect to mono fibers. The effect of hybridization of hooked end steel fibers with different length and diameter on mechanical properties of high strength concrete was investigated in this research work. The different percentages of hook ended fibers (60 mm and 40 mm) are hybridized in the concrete mixture while keeping total percentage of fibers by volume equal to 1%. The compressive and flexural properties with complete load verses deflection curves of hybrid steel fiber reinforced high performance concrete were investigated to find the optimized dosage of hybrid steel fibers. The results showed that the hybridization of fiber provided better compressive and flexural performance. It was also observed from the results that combination of 65% of 60 mm and 35% of 40 mm hooked end fibers proved to be best for enhancement in compressive and flexural properties.

scholarly journals SIFCON-A High Performance Concrete - Experimental Investigations

2020 ◽  
Vol 10 (2) ◽  
pp. 109-112
Author(s):  
R.G. Sonone ◽  
Sanjay Kumar Sharma ◽  
H.K. Sharma
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Steel Fibers ◽  
Experimental Investigations ◽  
Cement Slurry ◽  
Seismic Excitations ◽  
Split Tensile Strength ◽  
Crack Arrester ◽  
Fibrous Concrete

This paper addresses the development of High Performance Concrete in the past along with the experimental work on properties of Slurry Infiltrated Fibrous Concrete (SIFCON). Slurry infiltrated fibrous concrete has high strength, large ductility and good performance under seismic excitations. There is an increase in numbers of structures testified by the recent symposiums and conferences held on HPFRC. Now presently investigations are being carried out to suggest recommendations for the design of HPFRC structures. SIFCON consist of cement slurry and different types of steel fibers. It is observed that with the increase in percentage of steel fibers there is an improved static, dynamic and mechanical properties of concrete. Steel fibers also act as crack arrester and improve durability. In the present study, it is observed that at 9% fiber content the compressive strength, split tensile strength and flexural strength is optimum.

Estimation of Shear Behavior of Ultra High Performance Concrete I Girder without Shear Stirrups

2012 ◽  
Vol 525-526 ◽  
pp. 557-560
Author(s):  
Jung Woo Lee ◽  
Chang Joh ◽  
E.S. Choi ◽  
I.J. Kwak ◽  
Byung Suk Kim
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Crack Opening ◽  
Experimental Studies ◽  
Design Procedure ◽  
High Strength ◽  
Shear Behavior ◽  
Ultra High Performance Concrete ◽  
Shear Design ◽  
Loss Of Strength

Thinner and lighter members can be designed by utilizing the high stiffness and toughness, and high compressive strength of Ultra High Performance Concrete (UHPC), which reaches up to 180MPa. This high strength and ductile tensile behavior of UHPC makes it possible to design the web of the UHPC I Girder without conventional shear stirrups, which makes the UHPC I girder slender, light and economical. However, establishing shear design procedure for UHPC I girders without stirrups requires additional theoretical and experimental studies. This paper investigated shear behavior of UHPC I girder without shear stirrups. The test results show, in spite of no shear stirrups, test specimens have high ductility due to the bridging action of steel fibers against crack opening. UHPC I girders without shear stirrups tested show gradual increase of strength after initial cracking instead of brittle loss of strength as expected from the ordinary reinforced concrete I girders without stirrups. The decrease of the shear span-depth ratio increase the shear strength of the UHPC I girder without stirrups.

scholarly journals Fundamental Investigations on the Performance of Micro Steel Fibres in Ultra-High-Performance Concrete under Monotonic and Cyclic Tensile Loading

2021 ◽  
Vol 11 (20) ◽  
pp. 9377
Author(s):  
Jan-Paul Lanwer ◽  
Martin Empelmann
Keyword(s):  
Cyclic Loading ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Tensile Tests ◽  
Fatigue Behaviour ◽  
Dead Weight ◽  
Steel Fibres ◽  
Test Programme ◽  
The Impact

: Ultra-high-performance fibre-reinforced concrete (UHPFRC) can preferably be used for lean and thin-walled structures due to its very high compressive strength. Based on the adverse relation between the increased load bearing capacities and the condensed dead weight of UHPFRC-structures, the impact of live loads in the design gets bigger and, in case of traffic loads, the effects of a cyclic loading have to be considered in more detail. In this context, this study investigated the material behaviour of UHPFRC, especially the tensile fatigue behaviour of high-strength micro steel fibres and the bond behaviour between those fibres and plain UHPC. The test programme included once tensile tests of high-strength micro steel fibres under monotonic and cyclic loading. Based on the test results, an S/N-curve was set up with the characteristic values. Furthermore, the test programme included pullout tests of fibre groups with different embedded lengths and orientations under monotonic and cyclic loading. It was observed that some fibres rupture under certain test configurations like the angle of orientation and the load amplitude.

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