scholarly journals Experimental Study on Shear Performance of Cast-In-Place Ultra-High Performance Concrete Structures

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3254 ◽  
Author(s):  
Li ◽  
Feng ◽  
Ke ◽  
Pan ◽  
Nie
Keyword(s):  
Shear Strength ◽  
High Performance ◽  
Fiber Volume Fraction ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
Volume Fraction ◽  
Steel Fibers ◽  
Direct Shear ◽  
Ultra High Performance Concrete ◽  
Fiber Volume

In order to study the direct shear properties of ultra-high performance concrete (UHPC) structures, 15 Z-shaped monolithic placement specimens (MPSs) and 12 Z-shaped waterjet treated specimens (WJTSs) were tested to study the shear behavior and failure modes. The effects of steel fiber shape, steel fiber volume fraction and interface treatment on the direct shear properties of UHPC were investigated. The test results demonstrate that the MPSs were reinforced with steel fibers and underwent ductile failure. The ultimate load of the MPS is about 166.9% of the initial cracking load. However, the WJTSs failed in a typical brittle mode. Increasing the fiber volume fraction significantly improves the shear strength, which can reach 24.72 MPa. The steel fiber type has little effect on the shear strength and ductility, while increasing the length of steel fibers improves its ductility and slightly reduces the shear strength. The direct shear strength of the WJTSs made from 16 mm hooked-type steel fibers can reach 9.15 MPa, which is 2.47 times the direct shear strength of the specimens without fibers. Finally, an interaction formula for the shear and compressive strength was proposed on the basis of the experimental results, to predict the shear load-carrying capacity of the cast-in-place UHPC structures.

scholarly journals Influence of Fiber Volume Fraction and Fiber Orientation on the Uniaxial Tensile Behavior of Rebar-Reinforced Ultra-High Performance Concrete

Fibers ◽  
2019 ◽  
Vol 7 (7) ◽  
pp. 67 ◽  
Author(s):  
Manish Roy ◽  
Corey Hollmann ◽  
Kay Wille
Keyword(s):  
Fiber Orientation ◽  
High Performance ◽  
Fiber Volume Fraction ◽  
High Performance Concrete ◽  
Volume Fraction ◽  
Tensile Behavior ◽  
Uniaxial Tensile ◽  
Ultra High Performance Concrete ◽  
Load Direction ◽  
Fiber Volume

This paper studied the influence of fiber volume fraction ( V f ), fiber orientation, and type of reinforcement bar (rebar) on the uniaxial tensile behavior of rebar-reinforced strain-hardening ultra-high performance concrete (UHPC). It was observed that the tensile strength increased with the increase in V f . When V f was kept constant at 1%, rebar-reinforced UHPC with fibers aligned with the load direction registered the highest strength and that with fibers oriented perpendicular to the load direction recorded the lowest strength. The strength of the composite with random fibers laid in between. Moreover, the strength, as well as the ductility, increased when the normal strength grade 60 rebars embedded in UHPC were replaced with high strength grade 100 rebars with all other conditions remaining unchanged. In addition, this paper discusses the potential of sudden failure of rebar-reinforced strain hardening UHPC and it is suggested that the composite attains a minimum strain of 1% at the peak stress to enable the members to have sufficient ductility.

Study on Long-Term Expansive Deformation of Self-Stressing Concrete with Combined Restrictions of Steel Fibers and Steel Bar

2010 ◽  
Vol 452-453 ◽  
pp. 533-536 ◽  
Author(s):  
Huan An He ◽  
Wei Dong ◽  
Zhi Min Wu
Keyword(s):  
Prestressed Concrete ◽  
High Performance ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
Volume Fraction ◽  
Steel Fibers ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
Expansive Concrete

Self-stressing concrete is sort of expansive concrete with high expansion energy which can induce prestresses with restriction in concrete, and steel fibers also enhance tensile strength of concrete. The combination of these two high performance concrete can be used to improve the cracking resistance of concrete significantly. However, like mechanical prestressed concrete, a stable long-term prestresses (self-stresses) level is a key to exploit the particular advantage of steel fiber reinforced self-stressing concrete. Self-stresses are created by restricting the expansion of self-stressing concrete with steel bars or/and steel fibers, therefore, in this paper a series of tests on long-term expansive deformation of concrete were carried out by means of measuring restrict expansive deformation of self-stressing concrete with restriction of steel fibers. The results of tests showed, based on the three-year recording, that the expansive deformation of steel fiber reinforced self-stressing concrete almost kept the same as that of 28-day without remarkable rebound which indicated that losses of self-stresses were not significant and can meet the design requirements on self-stresses level. In addition, it is proposed on the relationship between restrict expansive deformation and reinforcement ratio of steel rebars under different steel fiber volume fraction from 0-2%.

Research on Long-Term Expansive Deformation of Steel Fiber Reinforced Expansive Concrete

2009 ◽  
Vol 417-418 ◽  
pp. 945-948
Author(s):  
Huan An He ◽  
You Gang Wang
Keyword(s):  
High Performance ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
Volume Fraction ◽  
Steel Fibers ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
Expansive Concrete ◽  
Steel Bar

The inherent low tensile strength and shrinkage result in cracking of concrete under work loads. A new way to improve cracking properties is distributing steel fibers into expansive concrete to form a type of composite which is called steel fiber reinforced expansive concrete. This type of high performance concrete could compensate shrinkage as well as improving crack strength. For this concrete, the key point to ensure high performance and safety of concrete structure is to keep a stable expansive deformation during long-term service. A series of tests were carried out to measure long-term restrained expansive deformations of steel fiber reinforced expansive concrete with ages under various restrictions like steel bars and steel fibers. The test investigated some 3-year specimens. For all specimens, test parameters included 2 ratios of steel bar reinforcement, 4 volume fractions of steel fiber and 4 dosages of expansion admixture. The test results showed that the expansion of concrete decreased with increasing of steel bar reinforcing ratio as well as steel fiber volume fraction. In addition, when being in a lower dosage of expansion admixture, the specimens presented remarkable retraction of the expansive deformation. However, when beyond a certain dosage of expansion admixture, the long-term expansive deformation had less change with ages and almost remained the same with 90-day deformation, namely less losses of deformation. Hence, for steel fiber reinforced expansive concrete, using an appropriate dosage of expansion admixture could meet the requirements of designed strengthening and compensating shrinkage.

scholarly journals Evaluation of the Ultimate Strength of the Ultra-High-Performance Fiber-Reinforced Concrete Beams

2021 ◽  
Vol 11 (7) ◽  
pp. 2951
Author(s):  
Baek-Il Bae ◽  
Moon-Sung Lee ◽  
Chang-Sik Choi ◽  
Hyung-Suk Jung ◽  
Hyun-Ki Choi
Keyword(s):  
Tensile Strength ◽  
Shear Strength ◽  
Ultimate Strength ◽  
High Performance ◽  
Fiber Volume Fraction ◽  
Steel Fiber ◽  
Volume Fraction ◽  
Fiber Reinforced Concrete ◽  
Fiber Volume ◽  
High Performance Fiber

Evaluation of the ultimate strength for the UHPFRC (ultra-high-performance fiber-reinforced concrete) flexural members was conducted. In this study, an experimental program about UHPFRC beams was conducted with the effect of fiber volume fraction, shear span to depth ratio, and compressive strength of matrix as the main variables. Among them, it was found that fiber volume fraction was the variable that had the greatest influence on the ultimate strength. The inclusion of 2% volume fraction steel fiber increases the shear and flexural strength of UHPFRC beams significantly. In particular, steel fiber inclusion changed the mode of failure of beams from diagonal shear failure into flexural failure. For the classification of failure patterns, the ultimate flexural strength and shear strength of UHPFRC members were evaluated using the current design code and UHPC guidelines. Flexural ultimate strength was affected by the size and shape of the stress block and consideration of the matrix’s tensile strength. For the accurate shear strength prediction of UHPFRC beams, the tensile strength of the high strength matrix and the effect of steel fiber should be considered.

Mechanical Behavior of UHPC(Ultra High Performance Concrete) According to Hybrid Use of Steel Fibers

2011 ◽  
Vol 287-290 ◽  
pp. 453-457 ◽  
Author(s):  
Gum Sung Ryu ◽  
Su Tae Kang ◽  
Jung Jun Park ◽  
Kyung Taek Koh ◽  
Sung Wook Kim
Keyword(s):  
Flexural Strength ◽  
High Performance ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
Steel Fibers ◽  
Single Type ◽  
Behavioral Characteristics ◽  
Total Rate ◽  
Ultra High Performance Concrete ◽  
Load Bearing Capacity

This intends to examine the flexural behavioral characteristics of hybrid UHPC using a mix of steel fibers with different lengths. Three types of fibers are adopted with fixed diameter of 0.2 mm and lengths of 13, 16.3 and 19.5 mm (aspect ratio of 65, 82 and 98, respectively). Comparative analysis of the flexural strength, load bearing capacity, deflection and toughness is performed adopting a mix use of these 3 types of steel fibers with ratio of 2% and 1.5%. The results show that the hybrid use of steel fibers improves significantly the flexural strength and flexural toughness compared to the use of a single type of fiber. When steel fibers with lengths of 16.3 mm and 19.5mm are admixed at a rate of 1% each, UHPC develops a flexural strength larger by 27% (maximum 50%) than conventional UHPC admixed with 2% of steel fiber with length of 13 mm. Moreover, flexural strength similar to that of conventional UHPC is secured when steel fibers with lengths of 16.3 mm and 19.5mm are admixed at respective rates of 0.5% and 1% (total rate of 1.5%).

Experimental Study of Strengthening and Toughening for Recycled Steel Fiber Reinforced Ultra-High Performance Concrete

2014 ◽  
Vol 629-630 ◽  
pp. 104-111 ◽  
Author(s):  
Gai Fei Peng ◽  
Xu Jing Niu ◽  
Qian Qian Long
Keyword(s):  
Mechanical Properties ◽  
Fracture Energy ◽  
High Performance ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
Steel Fibers ◽  
Fiber Reinforced ◽  
Ultra High Performance Concrete ◽  
Tensile Splitting Strength ◽  
Recycled Steel

This paper presents an experimental investigation on mechanical properties (including compressive strength, tensile splitting strength and fracture energy) of ultra-high performance concrete (UHPC) with recycled steel fiber, compared with none fiber and industrial steel fiber reinforced UHPC. Moreover, the microscopic observation of fracture energy was carried out. All specimens were prepared at 0.18 water /binder (W/B) ratio and the dosage of steel fiber was controlled at 60 kg/m3. The results indicate that recycled steel fiber has a significant effect on enhancing strength and toughness of UHPC. And owing to the crimped shape, higher tensile strength (1800-2000 MPa) and appropriate diameter (1 mm) of recycled steel fiber, the steel fibers of UHPRSFRC will not immediately be pulled off and necking phenomenon is distinct.

The Effect of Volume Fraction of Steel Fiber on the Tensile Softening Behavior in Ultra High Performance Concrete

2008 ◽  
Vol 385-387 ◽  
pp. 781-784
Author(s):  
Su Tae Kang ◽  
Jung Jun Park ◽  
Sung Wook Kim ◽  
Kee Nam Hong
Keyword(s):  
Crack Width ◽  
High Performance ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
Volume Fraction ◽  
Bending Test ◽  
Crack Model ◽  
Ultra High Performance Concrete ◽  
Softening Behavior ◽  
Tensile Softening

This paper estimated the influence of volume of steel fiber on the tensile softening behavior in Ultra High Performance Concrete. Tensile softening curves were obtained from Three-Point Bending Test(TPBT) with notched beam. Inverse analysis method by Uchida et al. was introduced to obtain the tensile softening behaviors from the results of TPBT. We could find out that the increase of volume fraction of steel fiber makes the tensile strength higher but all of the curves converged on an asymptote with crack width. We proposed the equation of softening curve expressed by combination of plastic area and exponential descending area considering the volume fraction of steel fiber and ω0, which is corresponding to the maximum crack width of plastic area. We also carried out the crack propagation analysis using finite element method with smeared crack model and confirmed that the proposed equation had a good agreement with the experimental results.

scholarly journals Residual Tensile Stress Estimation for Shear Strength of UHPC Nonprismatic Beams

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Nasser Hakeem Tu’ma ◽  
Mustafa Raad Aziz ◽  
Haider Jabbar J. Barry
Keyword(s):  
Shear Strength ◽  
Tensile Stress ◽  
High Performance ◽  
High Performance Concrete ◽  
Longitudinal Axis ◽  
Steel Fibers ◽  
Experimental Program ◽  
Residual Tensile Stress ◽  
Ultra High Performance Concrete ◽  
Failure Patterns

Abstract Estimating the shear strength of Ultra-High-Performance Concrete (UHPC), with high compressive and tensile strengths, is complicated by many variables that affecting its behavior. Residual tensile stress (RTS) plays an important role in raising the efficiency of both types of resistance, especially shear strength due to the presence of steel fibers, which makes it difficult to quantify the residual tensile stress due to the different failure patterns of these fibers and the distribution mechanism within the concrete matrix. There is no study to date in assessing residual tensile stress of UHPC structural members of the variable section. Thirteen beams were selected as an experimental program to study six main variables in determining shear strength. Stirrups ratio, flexural reinforcement ratio, the volumetric fraction of steel fibers, geometry changing, existing openings along the longitudinal axis, and shear span to depth ratio. According to on Tests results, RTS is compatible with most of the global specifications.

scholarly journals Steel Fiber Enhancement upon Punching Shear Strength of Concrete Flat Plates Exposed to Fire Flame

2021 ◽  
Vol 7 (10) ◽  
pp. 1667-1678
Author(s):  
Ahmed Naji Dalaf ◽  
Shatha Dheyaa Mohammed
Keyword(s):  
Shear Strength ◽  
Fiber Volume Fraction ◽  
Steel Fiber ◽  
Volume Fraction ◽  
Punching Shear ◽  
Flat Plates ◽  
Fiber Volume ◽  
Steady State Temperature ◽  
Fire Effect ◽  
Fire Flame

In this study, the effect of fire flame on the punching shear strength of steel fiber reinforced concrete flat plates was experimentally investigated using nine half-scale specimens with dimensions of 1500×1500 mm and a total thickness of 100 mm. The main investigated variables comprised the steel fiber volume fraction 0, 1, and 1.5% and the burning steady state temperature 500 and 600 °C. The specimens were divided into three groups, each group consists of three specimens. The specimens in the first group were tested with no fire effect to be the reference specimens, while the others of the second and third groups were tested after being exposed to fire-flame effect. The adopted characteristics of the fire test were; (one hour) burning time duration and 500 and 600 °C steady state temperature with sudden cooling process (water sprinkling directly after burning). The test results proved that exposing to direct fire effect for one hour caused a reduction in the punching shear strength with an increase in the ultimate mid-span deflection. Also, it was noticed that using steel fiber in the concrete mix leads to a significant increase in the punching shear strength for both the unburned and burned specimens. The ultimate punching load increased by about 11 and 16.6% for the unburned specimens with 1.0 and 1.5% steel fiber volume fraction, respectively, and by about 22.4 and 19% for the burned specimens at 500 °C with 1.0 and 1.5% steel fiber volume fraction, respectively. While, it was increased by about 29.2 and 21.5% for the burned specimens at 600 °C with 1.0 and 1.5% steel fiber volume fraction, respectively, as compared with the reference specimen of each group. Doi: 10.28991/cej-2021-03091751 Full Text: PDF

Flexural Toughness of Hybrid Fiber Reinforced High-Performance Concrete under Three-Point Bending

2013 ◽  
Vol 357-360 ◽  
pp. 1110-1114
Author(s):  
Dong Tao Xia ◽  
Xiang Kun Liu ◽  
Bo Ru Zhou
Keyword(s):  
Tensile Strength ◽  
High Performance ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
Volume Fraction ◽  
Polypropylene Fiber ◽  
Fiber Reinforced ◽  
Hybrid Fiber ◽  
Fiber Volume ◽  
Flexural Toughness

A set of new hybrid fiber reinforced high-performance concrete was developed and studied by experiment. The fibers incorporated the concrete are the collection of the steel fiber, modified polypropylene fiber and polypropylene with total fiber content not more than 1%. And the compressive test, splitting tensile test and the flexural toughness test were performed on eight groups of specimens. Based on the load-deflection and load-CMOD curves and the equivalent flexural tensile strength, the effect of fiber volume fraction and hybrid mode upon concrete's mechanical properties and post-peak behavior were investigated. The test results show that the mixing of the three different fibers can increase concrete's splitting tensile strength and flexural toughness more effectively with no significantly effect on compressive strength. The mixture of the three different fibers exist the optimization problem. Based on the results of the analysis, the compatible proportion of the three fibers is 0.7% steel fiber, 0.19% modified polypropylene fiber and 0.11% polypropylene fiber.

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