Types Of Steel Fibers Research Articles

Fibre-Reinforced Grout for Micropile Construction

Hollow bar micropiles (HBMP) are increasingly used to support heavy structures owing to their ability to carry considerable axial loads. However, their lateral capacity is relatively small due to their small flexural strength, which could limit their application for structures subjected to large lateral loads. Enhancing the micropile flexural strength by utilizing fibre-reinforced grout in its construction can thus improve its lateral performance. This study investigates the use of four types of fibers in grout mixture with different dosages to enhance the strength of grout used for micropile construction. Plastic, basalt, steel and micro-steel fibers were applied with dosages of 1%, 1.5% and 2%. Based on the obtained results, steel fibers were selected for further investigation. Nine model micropiles 1000 mm long and 76 mm in diameter were casted and tested in a laboratory environment with two different types of steel fibers. The micropiles were subjected to pure bending tests and the moment – curvature curves were extracted. The moment – curvature results indicated that the micropiles moment capacity increased and their post-cracking behaviour improved by adding steel fibers to the grout mix. As part of a large-scale study of lateral performance of single and grouped micropiles installed in cohesionless soil, one micropile was constructed with 1% micro-steel fiber to investigate its effect on its lateral performance. The lateral load test results indicated that the lateral capacity of the reinforced micropile improved by 10% over that of the non-reinforced micropile.

Effects of nano-SiO2 coating and induced corrosion of steel fiber on the interfacial bond and tensile properties of ultra-high-performance concrete (UHPC)

In this study, the effects of nano-silica (SiO2) coating and induced corrosion of steel fibers on the interfacial bond and tensile properties of ultra-high-performance concrete (UHPC) were investigated. Two different types of steel fibers were prepared: plain and nano-SiO2-coated. Corrosion was induced in each of these to two different degrees (2% and 5% by weight) using a 3.5% standard sodium chloride (NaCl) solution. The test results indicate that nano-SiO2 coating increases the bond strengths of steel fibers embedded in UHPC by approximately 50%. Furthermore, more scratches and higher hydrate contents were detected on the surface of nano-SiO2 coated steel fibers after pulling out from UHPC. Under tension, the UHPC containing nano-SiO2-coated steel fibers exhibited double the strain energy density, compared to that containing plain steel fibers. Moderately corroded steel fibers resulted in higher interfacial bond strength and energy absorption capacity owing to the increased surface roughness. In addition, the nano-SiO2 coating enhanced the tensile performance of UHPC even under corrosive environments. This enhancement was however diminished by steel fiber corrosion, so that fiber corrosion needs to be carefully controlled when nano-SiO2-coated steel fibers are used for UHPC.

Modeling the contribution of tire-reclaimed and industrial steels fibers on the strength and ductility of RC-frames structures

PurposeThis paper aims to model the performances of frames structures by comparing the predictions of ordinary control concrete (CC) and concretes reinforced by fibers. Two types of steel fibers were used in this work, industrial steel fibers (ISF) and tire-reclaimed fibers obtained by cutting virgin steel tire-cord to 50 mm, noticed virgin steel fibers (VSF). In total, 3% of VSF are used. The results obtained in this paper clearly show the contribution of fibers in improving the global and local behavior of the frames structures. VSF gives the same or better overall behavior as the use of industrial fibers for the same percentage of fibers, with the advantage that VSF contributes to the protection of the environment and limit the wastage of steel.Design/methodology/approachThis work was carried out using the commercial finite element code Abaqus/Explicit. The behavior of the different concretes used in this study was modeled by the concrete damage plasticity (CDP) constitutive law. The methodology adopted to complete this work consisted in identifying, by calibration of the available experimental results with the numerical predictions, the parameters of the corresponding CDP model for each of the concretes used in this work. To this end, the authors have successively identified the CDP parameters for the CC-V (control concrete used by Vecchio and Emara, 1992) used in frame structure (R + 1). Subsequently, the CDP parameters of the CC-T (control concrete used by Tlemat, 2004), the CVSF (concrete with virgin steel fibers) and the CISF-1 (concrete with industrial steel fibers type 1, ISF-1) are identified using the experimental results of beams under bending tests. Once the model parameters were determined for each concrete, the authors conducted a series of simulations to show the benefit of introducing claimed and industrial fibers in frame structure (R + 1) and (R + 2). This approach recommends the use of concrete reinforced with steel fibers, mainly 6% by mass of VSF and ISF-1, in place of ordinary concrete in new construction to increase the resistance of structures and contribute, if applicable, to the protection of the environment.FindingsThe main findings of this study can be summarized by: the strength and ductility of the frames structures made of concrete fiber are significantly increased. The use of tire-reclaimed steel fibers (VSF) gives the same or better overall behavior as the use of industrial fibers. In addition to their good mechanical contribution, the tire-reclaimed fibers contribute to the protection of the environment and limit the wastage of steel. The use of fibers reduces the cracking zones in concrete fiber frames structures. The usefulness of distinguishing the interstory displacement limits set by codes, in particular, uniform building code (UBC-97), for ordinary concretes and concrete reinforced with fibers is addressed.Originality/valueThe contribution of tire-reclaimed and industrial fibers on the strength and ductility of reinforced concrete-frames structures is addressed. The use of tire-reclaimed steel fibers gives the same or better overall behavior as the use of industrial fibers, the tire-reclaimed fibers having the advantage of contributing to the protection of the environment and limiting the wastage of steel. The paper also points to the usefulness of distinguishing the interstory displacement limits set by codes, in particular UBC-97, for ordinary concrete and concrete reinforced with fibers, in accordance to the predictions of the capacity curves.

Study on bonding compression-shear performance between industrial green fiber-reinforced concrete and old concrete

Industrial green fiber-reinforced concrete, a new hybrid high performance environmental protection material, can be made by adding recycled steel fibers into concrete in a certain proportion. As a composite material used in the construction industry, it can provide a new research direction for national green and sustainable development. This paper studied the interface bonding mechanism of normal steel fiber-reinforced old and new concrete and industrial green fiber-reinforced concrete and old concrete by using a self-made new fixture, and discussed the influence of compressive stress, types of steel fibers and recycled steel fiber content on the bonding compression-shear performance of specimens. The results show that the bonding compression-shear performance of specimens gradually increases with the increases of the compressive stress acting perpendicular to the shearing surface within the range of low compressive stress, and when the compressive stress is from 0.2 MPa to 1.0 MPa, the increased amplitude of the bonding compression-shear performance of specimens gradually increases, when the compressive stress is from 0.6 MPa to 1.0 MPa, the increased amplitude of the bonding compression-shear performance of specimens reaches the maximum, and when the compressive stress is from 1.0 MPa to 1.4 MPa, the increased amplitude of the bonding compression-shear performance of specimens decreases. Under the same conditions, the effect of the recycled steel fibers on improving the bonding compression-shear performance between old and new concrete is better than normal steel fibers. The bonding compression-shear performance between old and new concrete gradually increases with the increases of the volume ratio of recycled steel fibers, and when the fiber content is from 0.0 % to 1.0 %, the increased amplitude of the bonding compression-shear performance of specimens gradually increases, when the fiber content is from 0.5 % to 1.0 %, the increased amplitude of the bonding compression-shear performance of specimens reaches the maximum, and when the fiber content is from 1.0 % to 1.5 %, the increased amplitude of bonding compression-shear performance of specimens decreases. The simulation results of industrial green fiber-reinforced concrete and old concrete specimens with fiber content of 1.5 % under different compressive stresses are basically in agreement with the experimental results. This study can provide references for the research of bonding compression-shear behavior of steel fiber-reinforced old and new concrete materials and the recycling of steel wire from waste tires.

Experimental and Analytical Investigation of Bond Behavior of Deformed Steel Bar and Ultra-High Performance Concrete

Ultra-high performance concrete (UHPC) has been demonstrated to be a realistic alternative to less maintenance and significantly longer service life due to its better mechanical properties and low permeability. The bond performance of the deformed steel bar embedded in UHPC is critically important for the safety of the UHPC structures. This paper conducted an experimental investigation on the bond behavior of deformed steel bars and UHPC. The impacts of loading method, UHPC strength, steel fiber type and content, rebar diameter, and cover thickness were studied. The testing results revealed that the specimens failed in three modes: pull-out, splitting + pull-out, and cone failure. The main factors affecting the bond strength are UHPC compressive strength, cover thickness, and fiber characteristics. The peak slip of rebar-UHPC increases with cover thickness and rebar diameter. Finally, an analytical model of the bond stress-slip relationship between the UHPC and deformed steel bar is obtained, which is in suitable agreement with the test results.

Prediction and developing of shear strength of reinforced high strength concrete beams with and without steel fibers using multiple mathematical models.

One of the methods to improve the structural design of concrete is by updating the factors given in standard codes, especially when non-conventional materials are used in concrete beams. Accordingly, this study focuses on the colorations between the compressive strength and shear strength of high-strength concrete beams with and without steel fibers. For that purpose, different models are proposed to predict shear strength of high-strength concrete beams, by taking different combinations of the main variables: beam cross-section dimension (width and effective depth), reinforcement index, concrete compressive strength, shear span ratio, and steel fiber properties (volumetric content, fiber aspect ratio, and type of steel fibers). Multi-linear and non-linear regression analyses are used with large database experimental results found in the literature. The predicted results from the proposed equations are composed with different available models from codes, standards, and literatures. The calculated results showed better correlations and were close enough to the experimental data. Based on the data given in the standard codes, the shear strength is proportional to compressive strength ([Formula: see text]) of the power 0.5. However, this value may not be adequate for modern cement and concrete containing steel fibers. Therefore, the mentioned power value must be reduced 5 times to 0.1.

Improving the tensile resistance at high strain rates of high-performance fiber-reinforced cementitious composite with twisted fibers by modification of twist ratio

This study aims to examine effects of twist ratio on the tensile resistance at high strain rates and strain rate sensitivity of high-performance fiber-reinforced cementitious composites (HPFRCCs) with a small amount of twisted fibers. Two types of twisted steel fibers with different twist ratios, T3-fibers (3 twists/30 mm) and T9-fibers (9 twists/30 mm), were incorporated at 1% by volume into two matrices with different matrix strengths, M1 (56 MPa) and M2 (84 MPa). The direct tensile test results indicated that HPFRCCs with 1% twisted fibers generated not only high tensile resistance at high strain rates but also great rate sensitivity by maintaining tensile strain hardening accumulated with multiple micro cracks at high strain rates. T9-fibers produced the highest tensile resistance at high strain rates in M1 whereas T3-fibers did in M2. In addition, T9-fibers exhibited lower rate sensitivity than T3-fibers in all matrices. Theoretical models have been used successfully to predict dynamic post cracking strength of HPFRCCs with twisted fibers considering number of twists and the predicted results showed good agreements compared to the experimental results.

Experimental Database on pullout bond performance of steel fiber embedded in ultra-high-strength concrete

The bond strength between the steel fiber and the ultra-high performance concrete (UHPC) matrix plays a significant role in improving the behavior of plain UHPC. This paper compiles the existing experimental research database on the pullout bond performance of steel fibers embedded in UHPC. The variations of key parameters in the database are the steel fiber type and geometry, fiber volume fractions, and fiber embedded length. The effects of these parameters are analyzed and discussed in detail. Based on the analysis of the results, it was found that the deformed steel fibers, i.e., the hooked-end, half-hooked-end, and twisted steel fibers clearly provided higher average bond strengths than that straight fibers. The average pullout bond strength was obtained by increasing of fiber volume fraction in the UHPC matrix up to 2% (11.21MPa) with an increment of 20.4%. When the steel fiber volume fractions increase beyond 2%, the average bond strength decreases. Additionally, it was also found that using smaller embedded lengths in deformed steel fibers could result in the improvement of bond strength. This could be due to the fact that the bond is controlled by the mechanical anchorage of the end-hook rather than the physio-chemical bond in the straight portion. Conversely, increasing the embedded length of steel fiber could greatly contribute to the enhancement of pullout resistance resulting in increased bond strength between the UHPC matrix and steel fibers.

SHEAR BEHAVIOR OF FIBROUS REINFORCED CONCRETE WIDE BEAMS

When a reinforced concrete beam does not have enough shear strength and / or little amount of secondary rebar are reinforced, the "shear failure" is possible. Such type of failure is not acceptable in civil engineering due it does not indicate any prior notice before the complete failure of the intended structural member. One of the most popular solutions to overcome such shortcoming is the addition of steel fibers due to the ability for enhancing mechanical properties and ductility. Wide beams are such beams that have high width if compared with its thickness, such structural members are frequent in many reinforced concrete building systems and may also face "shear failure" during its service life. The current study investigates the structural behavior of the Steel Fiber Reinforced Concrete Wide Beams by proposing an experimental program comprising casting and testing of twenty beams specimen. The effective shear spans to depth ratio ratios were 2.5 and 3.5, respectively. Two nominal strength levels 30 MPa "Normal strength concrete" and 60 MPa "High strength concrete are also included. The types of steel fibers used are the "End Hocked" as well as the "Staggered" in 0.5% and 1.5% volume fractions for each one. The results showed that the addition of steel fibers enhances the consequent mechanical properties and the relevant structural behavior of wide beams to a serious concern. Furthermore, the addition of steel fibers modified the shear failure mode to "flexural". The first cracking load increased in "Normal strength" from 21.95% to 73.73% by adding "End Hocked" and from 12.19% to 45.45% by adding "Staggered" while such range reported 15.95% to 45.76% for "End Hocked" and 7.25% to 28.81% for "Staggered" in "High strength". Additionally, the ultimate load increased in "Normal strength" from 19.75% to 65.98% by adding "End Hocked" and from 10.52% to 43.81% by adding "Staggered" while such range reported 13.5% to43.57 % for "End Hocked" and 7.25% 29.29to % for "Staggered" in "High strength".

Deep learning and machine learning‐based prediction of capillary water absorption of hybrid fiber reinforced self‐compacting concrete

AbstractDeep auto‐encoders and long short‐term memory methodology (LSTM) based on deep learning as well as support vector regression (SVR) and k‐nearest neighbors (kNN) based on machine learning models for the capillary water absorption prediction of self‐compacting concrete (SCC) with single and binary, ternary, and quaternary fiber hybridization were developed. A macro and two types of micro steel fibers having different aspect ratios, and PVA fiber were used. One hundred and sixty‐eight specimens produced from 24 mixtures were used in the prediction models. The input was the content of cement, fly ash, silica fume, fine and coarse aggregate, water, superplasticizer (SP), macro and micro steel fibers, PVA, time that the specimen was immersed in water, and splitting tensile strength. Water absorption was used as output. As per the ANOVA analysis of the experiment results, the most effective parameters were macro steel fiber and time for tensile strength and water absorption, respectively. Finally, binary hybridization of 1% macro steel fiber and PVA improved the splitting tensile strength while the use of PVA as binary, ternary, and quaternary fiber hybridization increased the water absorption of SCC specimens. The auto‐encoder, LSTM, SVR, and kNN models predicted the water absorption of fiber reinforced SCC with 99.99%, 99.80%, 94.57%, and 95.50% accuracy, respectively. The performance of deep autoencoder in the estimation of water absorption of fiber‐reinforced SCC was superior to the other prediction models.

Shear strength prediction method of the UHPC keyed dry joint considering the bridging effect of steel fibers

The joints between segments of the precast ultra-high performance concrete (UHPC) segmental bridge (PUSB), which transmit compressive and shear stresses, require special attention in design. The shear strength of these joints is significantly improved in comparison with that of normal strength concrete (NSC) joints due to the excellent mechanical properties of UHPC. Nevertheless, little attention has been paid to predict the shear capacity of UHPC joints directly considering the shear contribution of steel fibers. This paper develops a new shear strength model for UHPC-keyed dry joints incorporating transferring mechanisms of three primary shear component based on previous experimental results and numerical simulation. Based on the modified compression-field theory, the shear contribution by the matrix in UHPC keys is mainly influenced by normal compressive stress and area of all bases of keys. Based on the mesoscale fiber–matrix discrete model, the shear contribution by steel fibers was affected by the steel fiber length, diameter, type, and volume fraction. To obtain more accurate prediction results, a reduction coefficient was utilized for UHPC multi-keyed dry joints in the proposed shear strength formula on grounds of regression analysis. The reliability and accuracy of these results were then verified by experimental results of 27 push-off tests available, with mean and standard deviations between the predicted and experimental shear strength of 0.98 and 0.27, respectively. Thus, the proposed formula can be used to predict the shear strength of UHPC dry joints with single and multiple shear keys.

Estimation of strengths of hybrid FR‐SCC by using deep‐learning and support vector regression models

AbstractIn this work, to estimate the compressive, splitting tensile, and flexural strength of self‐compacting concrete (SCC) having single fiber and binary, ternary, and quaternary fiber hybridization, the deep‐learning (DL) and support vector regression (SVR) models were devised. The fiber content and coarse aggregate/total aggregate ratio (CA/TA) were the variables for 24 designed mixtures. Four different fibers, which were a macro steel fiber, two types of micro steel fibers with different aspect ratio, and polyvinyl alcohol (PVA) fiber, were used in SCC mixtures. The specimens of each mixture were tested to measure the engineering properties for 7, 28, and 90 days. The amount of cement, fly ash, fine aggregate, CA, high‐range water‐reducing admixture, water, macro steel fiber, PVA fiber, two types of micro steel fibers, and curing time were selected as input layers while the output layers were strength results. The experimental results were compared with the estimation results. The engineering properties were estimated using the SVR model with 95.25%, 87.81%, and 93.89% accuracy, respectively. Furthermore, the DL model estimated compressive strength, tensile strength, and flexural strength with 99.27%, 98.59%, and 99.15% accuracy, respectively. It was found that the DL estimated the engineering properties of hybrid fiber–reinforced SCC with higher accuracy than SVR.

Empirical approach for the residual flexural tensile strength of steel fiber‐reinforced concrete based on notched three‐point bending tests

AbstractWhen designing steel fiber‐reinforced concrete, for example, according to Model Code 2010, the residual flexural strength values must be specified as fundamental properties. It is often difficult to establish the relationship between residual flexural strength values and the required dosage of steel fibers depending on the type of steel fibers and the concrete quality. For an estimation of the presumably necessary dosage of steel fibers, various empirical approaches exist for the approximate determination of the residual flexural strength values, which, however, are based on different tests and have been almost exclusively been derived on the basis of few or “own” test results of the respective institute. For this reason, the validity of the respective approximation approach is often limited. Using the bending beam database “Steel Fibre Reinforced Concrete”, selected approaches were systematically analyzed and an improved approach for determining the residual flexural strength values of steel fiber‐reinforced concrete was developed.

Structural behavior of high-strength concrete corbels involving steel fibers or closed stirrups

A comprehensive experimental evaluation of the shear behavior of corbels made by high-strength concrete (HSC) with steel fiber or with stirrups was investigated. Thirteen samples were prepared and tested, the main variables in this research were steel fiber type, steel fiber content (Vf %), and amount of horizontal closed stirrups (Ah). The constants in this investigation were the area of the main steel reinforcement (As), ratio of shear span to depth (a/d) and cube concrete strength (fcu). The obtained results clearly showed that, the presence of fibers or closed stirrups enhanced the strength and decreased the deformation of the explored specimens. It was concluded that the horizontal shear reinforcement can be substituted by supplementation of steel fibers to RHSC corbels. A comparison was performed between the test results and estimated shear capacity by ACI code and other adopted equations. Very conservative shear strength values were obtained from ACI 318–19 for corbels prepared with high-strength concrete because the strut and tie method were influenced by concrete strength and did not take the contribution of closed stirrups into account. However, the shear friction method depends only on the quantity of the main steel reinforcement and closed stirrups. Russo [2] proposed a model that adequately predicted the ultimate force of high-strength RC corbels incorporating closed stirrups, but this model did not take the effect of steel fibers into account. Campione [3] added the effect of steel fibers by means of the residual tensile strength expression.

Strength of SIFCON- Ferrocement One-Way Ribbed Slabs Contain Steel Fibers

Slurry infiltrated fiber concrete” composites (SIFCON) are a novel type of concrete with improved strength, ductility, and crack resistance. In this study, infiltrating fibers (SIFCON) were used to reinforce of specimens of ferrocement one way ribbed slabs. The laboratory work consists of cast and testing of eight specimens with dimensions of 750 mm in length, 500 mm in width and 50 mm in depth. These samples have the same wire mesh reinforcement and the same shape as the ferrocement slabs. Two reference ferrocement slab without ribs contains SIFCON and six ferrocement slabs with ribs contains SIFCON. The variables were the volumetric ratio of fibers in the ribs, which were (2, 4 and 6)% and type of steel fiber (hook-end and hybrid fiber). Hybrid fibers contain two type of steel fiber (hook-end and micro steel fiber) with equal ratio. All samples were tested under line load up to failure with mid deflections for each test with simple supported. The results of the test showed that the presence of steel fibers in the ferrocement ribs, for both types of steel fibers, improves the resistance to the final loads and the ability to reduce deflection and increases the ductility and stiffness significantly.

Теплопроводность сталефибробетона

The article presents the study results of the thermal conductivity of steel fiber reinforced concrete (SFRC) on a matrix of fine-grained concrete with different types of steel fibers and different content of fibers. It is shown, that with an increase in the volume content of steel fiber, the thermal conductivity coefficient of SFRC, depending on the diameter of the fiber, can either increase or decrease compared to the thermal conductivity coefficient of the matrix. The obtained result is explained based on the influence of both the ratio between the wavelength of infrared (thermal) radiation and the diameter of the steel fiber and the conditions of thermal flow passage through the fiber-matrix boundary on the thermal flow propagation.

Strength characteristics of concrete by utilization of metakaolin and steel fibres as partial substitute to binding material

Cement has an unresolved problem of increased utilization of raw materials and energy consumption and also carbon dioxide emission during its production. Metakaolin is utilized as partial substitute to cement. It utilizes lime on hydration and causes an increase in the production of cementitious compounds leading to improved strength. The principal intention of this research activity is to find out the fresh (workability) and hardened properties (compressive, split tensile and flexure) of concrete by using metakaolin at varying percentages from 0%, 5%, 10%, 15% and 20% by weight of cement and again by incorporating various types of steel fibers in the limit of 2%, 2.5%, 3% and 3.5%. Concrete specimens were cast for a M40 grade of concrete. Cube specimens (150 × 150 × 150 mm), cylindrical specimens (300 × 150 mm) and prism specimens (100 × 100 × 500 mm) were tested and evaluated for strengths in direct compression, tension and bending for 7 and 28 days of curing span. The outcomes were compared with normal mix. The results have shown that the increase in compressive, tensile and flexure were 20.29%, 16.13% and 14.4% respectively.

Mixed influence of steel fiber (SF) and metakaolin (MK) incorporation on mechanical properties of concrete

In this study, the influence of experimental analysis on the engineering properties of concrete containing metakaolin (MK) in different proportions, with and without steel fiber, is examined. Ordinary Portland cement is partially restored with MK 0, 5, 10, 15, and 20% by weight to produce metakaolin reinforced concrete, and the mechanical qualities of Steel fibers reinforcement are selected based on their mechanical characteristics at ideal proportions. To produce fiber-reinforced concrete, two distinct types of steel fibers are introduced into the admixtures. In terms of length and diameter, steel fiber SF1 measured 48 mm and 0.80 mm, whereas steel fiber SF2 measured 64 mm and 0.80 mm, respectively. According to the findings of the current investigation, using metakaolin in a proportion of around 10% by weight of cement in conjunction with 1.5 percent steel by weight of cement result in the optimum compression and split tensile strength of concrete. When we compare MK 10 percent to MK 20 percent, we see that there is a 4.28 percent reduction in strength. For trial mix 1, which was made of conventional concrete, the split tensile strength values were around 2.8 MPa after 7, 14 and 28 days of curing, and 3.1 MPa after 14 and 28 days of curing. When MK 5 percent is added, the STS increases by 12.5 percent, and when MK 10 percent is added, the STS increases by 28.6 percent. In contrasted to other mixes, the combination containing 10 percent MK has a higher level of potency. Strength is reduced by 2.85% when comparing the MK 20 percent mixture to the corresponding MK 5% combination. Therefore, we may infer that MK 10% should be considered the best proportion for cement inclusion. The findings clearly revealed that it enhances the strength capabilities of the concrete at various stages, with the amount of replacement largely determining the final strength capability.

Compressive Strength Improvement of Lightweight Concrete by Incorporation Waste Materials: An Experimental Investigation

In the world of depletion of resources, using recycled materials is getting more and more interesting, since recycling generally reduces the need for extracting, refining, and processing raw materials. In this study, attempts to investigate the effect of two types of steel fibers (staples) on concrete compressive strength have been experimentally accomplished. The different fibers at constant fractions of 0.5%, 1%, 1.5%, and 2 % by the weight of cement are used as reinforced agents with different curing duration times of steel fibers-normal concrete samples. The results obtained by the compressive strength test showed a significant improvement in the concrete compressive strength up to 47.8 MPa could be on hand with such simple reinforcement.

Research on the Fracture Behavior of Steel-Fiber-Reinforced High-Strength Concrete.

The behavior of steel fiber concrete, which is the most widely used building material, has been widely examined. However, methods for calculating Fracture parameters differ by fracture behavior of SFHSC with different strengths. In this study, the fracture behavior of steel-fiber-reinforced high-strength concrete (SFHSC) was -investigated using three-point bending tests. A total of 144 notched concrete beams with a size of 100 mm × 100 mm × 515 mm were tested for three-point bending in 26 groups. The effects of the steel fiber volume ratio, steel fiber type, and relative notch depth on the fracture toughness (KIC) and fracture energy (GF) of SFHSC specimens were studied. The results show that an increase in the volume fraction of steel fiber (ρf) added to high-strength concrete (HSC) significantly improves the fracture behavior of HSC. As compared to milled and sheared corrugated steel fibers, cut bow steel fibers significantly improve the fracture behavior of SFHSC. The effect of incision depth changes on the KIC and GF of SFHSC and HSC for the comparison group has no common characteristics. With an increase in incision depth, the values of KIC of the SFHSC specimens decrease slightly. The GF0.5/GF0.4 of the SFHSC specimens show a decreasing trend with an increase in ρf. According to the test results, we propose calculation models for the fracture behavior of SFHSC with different strengths. Thus, we present a convenient and accurate method to calculate fracture parameters, which lays a foundation for subsequent research.