scholarly journals Effect of Steel Fiber Content on Shear Behavior of Reinforced Expanded-Shale Lightweight Concrete Beams with Stirrups

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1107
Author(s):  
Changyong Li ◽  
Minglei Zhao ◽  
Xiaoyan Zhang ◽  
Jie Li ◽  
Xiaoke Li ◽  
...  
Keyword(s):  
Crack Width ◽  
Failure Modes ◽  
Steel Fiber ◽  
Lightweight Concrete ◽  
Volume Fraction ◽  
Shear Crack ◽  
Shear Capacity ◽  
Shear Cracks ◽  
Shear Cracking ◽  
Expanded Shale

To determine the validity of steel fiber reinforced expanded-shale lightweight concrete (SFRELC) applied in structures, the shear behavior of SFRELC structural components needs to be understood. In this paper, four-point bending tests were carried out on reinforced SFRELC beams with stirrups and a varying volume fraction of steel fiber from 0.4% to 1.6%. The shear cracking force, shear crack width and distribution pattern, mid-span deflection, and failure modes of test beams were recorded. Results indicate that the shear failure modes of reinforced SFRELC beams with stirrups were modified from brittle to ductile and could be transferred to the flexure mode with the increasing volume fraction of steel fiber. The coupling of steel fibers with stirrups contributed to the shear cracking force and the shear capacity provided by the SFRELC, and it improved the distribution of shear cracks. At the limit loading level of beams in building structures at serviceability, the maximum width of shear cracks could be controlled within 0.3 mm and 0.2 mm with the volume fraction of steel fiber increased from 0.4% to 0.8%. Finally, the formulas are proposed for the prediction of shear-cracking force, shear crack width, and shear capacity of reinforced SFRELC beams with stirrups.

scholarly journals Testing and Prediction of Shear Performance for Steel Fiber Reinforced Expanded-Shale Lightweight Concrete Beams without Web Reinforcements

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1594 ◽  
Author(s):  
Xiaoke Li ◽  
Changyong Li ◽  
Minglei Zhao ◽  
Hui Yang ◽  
Siyi Zhou
Keyword(s):  
Steel Fiber ◽  
Lightweight Concrete ◽  
Shear Capacity ◽  
Fiber Reinforced Concrete ◽  
Bending Test ◽  
Fiber Reinforced ◽  
Cracking Resistance ◽  
Shear Performance ◽  
Shear Cracking ◽  
Expanded Shale

In this paper, for a wide application of high-performance steel fiber reinforced expanded-shale lightweight concrete (SFRELC) in structures, the shear behavior of reinforced SFRELC beams without web reinforcements was experimentally investigated under a four-point bending test. Twenty-six beams were fabricated considering the influencing parameters of SFRELC strength, shear-span to depth ratio, longitudinal reinforcement ratio and the volume fraction of the steel fiber. The statistical analyses based on the foundational design principles and the experimental results are made based on the shear cracking resistance, the shear crack distribution and width, the mid-span deflection, the patterns of shear failure, and the shear capacity of the specimens. This confirms the effective strengthening of steel fibers on the shear performance of reinforced SFRELC beams without web reinforcements. Based on the modifications to the formulas of reinforced conventional concrete, lightweight-aggregate concrete or steel fiber reinforced concrete (SFRC) beams, and the validation against the experimental findings, formulas are proposed for the prediction of shear cracking resistance and shear capacity of reinforced SFRELC beams without web reinforcements. Finally, formulas are discussed for the reliable design of the shear capacity of reinforced SFRELC beams without web reinforcements.

scholarly journals Development of Steel Fiber-Reinforced Expanded-Shale Lightweight Concrete with High Freeze-Thaw Resistance

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Mingshuang Zhao ◽  
Xiaoyan Zhang ◽  
Wenhui Song ◽  
Changyong Li ◽  
Shunbo Zhao
Keyword(s):  
Steel Fiber ◽  
Lightweight Concrete ◽  
Volume Fraction ◽  
Content Volume ◽  
Steel Fibers ◽  
Fine Aggregate ◽  
Test Results ◽  
Fiber Reinforced ◽  
Freeze Thaw ◽  
Expanded Shale

For the popularized structural application, steel fiber-reinforced expanded-shale lightweight concrete (SFRELC) with high freeze-thaw resistance was developed. The experimental study of this paper figured out the effects of air-entraining content, volume fraction of steel fibers, and fine aggregate type. Results showed that while the less change of mass loss rate was taken place for SFRELC after 300 freeze-thaw cycles, the relative dynamic modulus of elasticity and the relative flexural strength presented clear trends of freeze-thaw resistance of SFRELC. The compound effect of the air-entraining agent and the steel fibers was found to support the SFRELC with high freeze-thaw resistance, and the mechanisms were explored with the aid of the test results of water penetration of SFRELC. The beneficial effect was appeared from the replacement of lightweight sand with manufactured sand. Based on the test results, suggestions are given out for the optimal mix proportion of SFRELC to satisfy the durability requirement of freeze-thaw resistance.

scholarly journals Complete Stress–Strain Curves of Self-Compacting Steel Fiber Reinforced Expanded-Shale Lightweight Concrete under Uniaxial Compression

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2979 ◽  
Author(s):  
Zhao ◽  
Zhang ◽  
Shang ◽  
Fu ◽  
Zhang ◽  
...  
Keyword(s):  
Uniaxial Compression ◽  
Steel Fiber ◽  
Lightweight Concrete ◽  
Volume Fraction ◽  
Compressive Strain ◽  
Strain Curve ◽  
Lightweight Aggregate Concrete ◽  
Fiber Reinforced ◽  
Stress Strain ◽  
Expanded Shale

To expand the structural application of steel fiber reinforced expanded-shale lightweight concrete (SFRELC), a self-compacting SFRELC with high-workability was developed based on previous research. As part of the investigation, the present study focuses on the adaptability of formulas used for the complete stress–strain curves of steel fiber reinforced lightweight-aggregate concrete and conventional concrete under uniaxial compression. On the basis of mix proportion of SFRELC, self-compacting SFRELC was designed with the volume fraction of steel fiber as 0%, 0.4%, 0.8%, 1.2%, 1.6%, and 2.0%. Eighteen cylindrical specimens with dimensions of Φ150 mm × 300 mm were tested to measure the uniaxial compressive stress–strain curves of self-compacting SFRELC. Results indicated that, with the increasing volume fraction of steel fiber, the compressive strain at the peak-stress of the stress–strain curve increased, while the slope of the descending portion decreased. This increased the energy absorption of self-compacting SFRELC with a higher compression toughness. With a comparison of test results between four groups of calculation models, a group of formulas is selected to express the complete stress–strain curves of self-compacting SFRELC under uniaxial compression.

scholarly journals Bond of Ribbed Steel Bar in High-Performance Steel Fiber Reinforced Expanded-Shale Lightweight Concrete

Buildings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 582
Author(s):  
Mingshuang Zhao ◽  
Guirong Liu ◽  
Lingli Liu ◽  
Yanyan Zhang ◽  
Kang Shi ◽  
...  
Keyword(s):  
Bond Strength ◽  
High Performance ◽  
Steel Fiber ◽  
Lightweight Concrete ◽  
Volume Fraction ◽  
Bond Stress ◽  
Fiber Reinforced ◽  
Bond Slip ◽  
Steel Bar ◽  
Expanded Shale

For the structural application of high-performance Steel Fiber Reinforced Expanded-shale Lightweight Concrete (SFRELC), a reliable bond of ribbed steel bar should be ensured. In this paper, an experimental study was carried out on the bond properties of ribbed steel bar embedded in SFRELC by the direct pull-out test. The SFRELC was produced with a strength grade of 35 MPa and a volume fraction of steel fiber as 0%, 0.8%, 1.2%, 1.6% and 2.0%, respectively. Fifteen groups of specimens were made with a central placed steel bar with diameter of 14 mm, 20 mm and 28 mm, respectively. Complete bond stress-slip curves were determined for each group of specimens, and the characteristic values of bond-stress and slip at key points of the curves were ascertained. Results show that the bond strength, peak-slip and residual bond strength increased with the increase of the volume fraction of steel fiber. With the increase of steel bar diameter, bond strength decreased while the peak-slip increased, and the descending curves became sharp with a decreased residual bond strength. Formulas for calculating the bond strength and peak-slip were proposed. The relationships were determined for the splitting bond strength, residual bond strength with the bond strength, the splitting bond slip and residual bond slip with the peak-slip. Combined with rational fitting analyses of bond strength and slip, a constitutive model was selected for predicting the bond stress-slip of ribbed steel bar in SFRELC.

scholarly journals Behavior of Rectangular-Sectional Steel Tubular Columns Filled with High-Strength Steel Fiber Reinforced Concrete Under Axial Compression

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2716 ◽  
Author(s):  
Shiming Liu ◽  
Xinxin Ding ◽  
Xiaoke Li ◽  
Yongjian Liu ◽  
Shunbo Zhao
Keyword(s):  
Energy Dissipation ◽  
Bearing Capacity ◽  
Failure Modes ◽  
Steel Fiber ◽  
Volume Fraction ◽  
Local Buckling ◽  
Steel Tube ◽  
Fiber Reinforced Concrete ◽  
Steel Fiber Reinforced Concrete ◽  
Energy Dissipation Capacity

This paper studies the effect of high-strength steel fiber reinforced concrete (SFRC) on the axial compression behavior of rectangular-sectional SFRC-filled steel tube columns. The purpose is to improve the integrated bearing capacity of these composite columns. Nine rectangular-sectional SFRC-filled steel tube columns and one normal concrete-filled steel tube column were designed and tested under axial loading to failure. The compressive strength of concrete, the volume fraction of steel fiber, the type of internal longitudinal stiffener and the spacing of circular holes in perfobond rib were considered as the main parameters. The failure modes, axial load-deformation curves, energy dissipation capacity, axial bearing capacity, and ductility index are presented. The results identified that steel fiber delayed the local buckling of steel tube and increased the ductility and energy dissipation capacity of the columns when the volume fraction of steel fiber was not less than 0.8%. The longitudinal internal stiffening ribs and their type changed the failure modes of the local buckling of steel tube, and perfobond ribs increased the ductility and energy dissipation capacity to some degree. The compressive strength of SFRC failed to change the failure modes, but had a significant impact on the energy dissipation capacity, bearing capacity, and ductility. The predictive formulas for the bearing capacity and ductility index of rectangular-sectional SFRC-filled steel tube columns are proposed to be used in engineering practice.

scholarly journals Flexural Fatigue Performance of Steel Fiber Reinforced Expanded-Shales Lightweight Concrete Superposed Beams with Initial Static-Load Cracks

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3261
Author(s):  
Fulai Qu ◽  
Changyong Li ◽  
Chao Peng ◽  
Xinxin Ding ◽  
Xiaowu Hu ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Static Load ◽  
Steel Fiber ◽  
Lightweight Concrete ◽  
Volume Fraction ◽  
Stress Amplitude ◽  
Flexural Stiffness ◽  
Compression Zone ◽  
Fatigue Load ◽  
Upper Limit

Concerning the structural applications of steel fiber reinforced expanded-shales lightweight concrete (SFRELC), the present study focuses on the flexural fatigue performance of SFRELC superposed beams with initial static-load cracks. Nine SFRELC superposed beams were fabricated with the SFRELC depth varying from 50% to 70% of the whole sectional depth, and the volume fraction of steel fiber ranged from 0.8% to 1.6%. The fatigue load exerted on the beams was a constant amplitude sinusoid with a frequency of 10 Hz and a fatigue characteristic value of 0.10; the upper limit was taken as the load corresponded to the maximum crack width of 0.20 mm at the barycenter of the longitudinal rebars. The results showed that with the increase of SFRELC depth and the volume fraction of steel fiber, the fatigue life of the test beams was prolonged with three altered failure modes due to the crush of conventional concrete in the compression zone and/or the fracture of the tensile rebar; the failure pattern could be more ductile by the prevention of fatigue fracture by the longitudinal tensile rebar when the volume fraction of steel fiber was 1.6% and the reduction of crack growth and concrete strain in the compression zone; the fatigue life of test beams was sensitive to the upper-limit of the fatigue load, a short fatigue life appeared from the higher stress level and larger stress amplitude of the longitudinal rebar due to the higher upper-limit of the fatigue load. The methods for predicting the stress level, the stress amplitude of the longitudinal tensile rebar, and the degenerated flexural stiffness of SFRELC superposed beams with fatigue life are proposed. With the optimal composites of the SFRELC depth ratio and the volume fraction of steel fiber, the controllable failure of reinforced SFRELC superposed beams could be a good prospect with the trend curves of fatigue flexural stiffness.

scholarly journals Effect of corrosion on the bond strength of self consolidated lightweight concrete

2021 ◽  
Author(s):  
Tariq Mumtaz
Keyword(s):  
Failure Modes ◽  
Lightweight Concrete ◽  
Strength Properties ◽  
Seismic Zone ◽  
Time Data ◽  
Voltage Versus ◽  
Accelerated Corrosion ◽  
Filling Ability ◽  
Expanded Shale ◽  
Passing Ability

Self-consolidating lightweight concrete (SCLWC) is a concrete with excellent filling ability, good passing ability, and adequate segregation resistance. The use of SCLWC can be beneficial for structures due to significant reduction in dead loads as well as structures in seismic zone. In addition, economic impacts on construction industry by using SCLWC will be significant because of its benefits. Three SCLWC mixtures are developed by using two types of lightweight aggregates (LWA) (such as blast furnace slag and expanded shale), two supplementary cementing materials (such as fly ash and metakaolin). In addition to fresh and strength properties, the effect of different degrees of accelerated corrosion on bond characterists of deformed steel bars in SCLWC is investigated by analyzing pullout test results such as load-slip relationship, voltage versus time data, failure modes, aggregate of specimens and concrete material characteristics.

Shear-Crack Behaviors of Reinforced Full-Recycled Aggregate Concrete Beams

2013 ◽  
Vol 438-439 ◽  
pp. 794-799 ◽  
Author(s):  
Chang Yong Li ◽  
Guang Xin Li ◽  
Wen Jing Shao ◽  
Qi Guo ◽  
Rui Liu
Keyword(s):  
Crack Width ◽  
Concrete Beams ◽  
Shear Crack ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Fine Aggregate ◽  
Aggregate Concrete ◽  
Shear Span ◽  
Shear Cracking

On the basis of experimental results, this paper discusses the shear-crack behaviors such as shear-cracking force and shear-crack width of reinforced full-recycled aggregate concrete beams. The full-recycled aggregate concrete was developed for the sustainable development in civil engineering, in which the coarse aggregate was the recycled aggregate made of abandoned concrete, and the fine aggregate was the machine-made sand. Sixteen beams, six of them without stirrups, were tested with the shear-span ratio varying as 1.5, 2.0 and 3.0, and the ratio of stirrups varying from 0.19% to 0.35%. The results showed that the shear-cracking force of the beam was mainly affected by the shear-span ratio, the width of shear-cracks intersecting stirrups decreased with the increasing ratio of stirrups, but the maximum crack width almost exceeded the limit 0.3mm in the first class environmental condition specified in Chinese code GB50010-2010. Comparing the calculation results by substituting the test parameters of full-recycled aggregate concrete beams into the formula of ordinary reinforced concrete beams, the lower resistance of reinforced recycled concrete beam to shear-cracking, and the larger crack width intersecting stirrups should be noted in the structural design. Based on the test data, the formula for calculating the shear-cracking force and the shear-crack width of reinforced full-recycled aggregate concrete beams are suggested.

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.

Sign in / Sign up

Export Citation Format

Share Document