Mechanical Properties and Volume Deformation of Steel Fiber Reinforced Micro-Expansive Concrete Filled Steel Tube

2012 ◽  
Vol 204-208 ◽  
pp. 4083-4087 ◽  
Author(s):  
Xiao Jun Zhou ◽  
Ting Min Mou ◽  
Bi Kun Fan ◽  
Qing Jun Ding
Keyword(s):  
Steel Fiber ◽  
Volume Fraction ◽  
Steel Tube ◽  
Fiber Reinforced ◽  
Volume Deformation ◽  
Concrete Filled Steel Tube ◽  
Expansion Test ◽  
Expansive Concrete ◽  
Deformation Behaviors ◽  
Splitting Tensile Test

Abstract: Steel fiber reinforced micro-expansive concrete (SREC) with excellent fluidity, high resistance to segregation and good self-compacting ability was prepared. Compressive test, splitting tensile test and flexural test were performed. Self-developed confined expansion test instrument of concrete filled steel tube (CFST) was used to evaluate the deformation behaviors of SREC confined in the steel tube. The structure behavior of steel fiber reinforced micro-expansive concrete filled steel tube (SECFST) was investigated through 12 short column specimens. Expansion agent invariant and steel fiber contents were the dominant variables. The results showed that when compared to common micro-expansive concrete, the splitting tensile and flexural strength of SREC were increased by 78.0% and 64.7%, respectively. When the expansion agent amount was 40kg and volume fraction of steel fiber was less than 1%, SECFST exhibited stable expansive deformation. The use of steel fiber combined with expansion agent moderately improved the yield load and ultimate load of CFST.

Frost Resistance of Steel Fiber Reinforced Micro-Expansive Concrete Filled Steel Tube

2012 ◽  
Vol 204-208 ◽  
pp. 3956-3960 ◽  
Author(s):  
Ting Min Mou ◽  
Xiao Jun Zhou ◽  
Bi Kun Fan ◽  
Qing Jun Ding
Keyword(s):  
Low Temperature ◽  
Frost Resistance ◽  
Steel Fiber ◽  
Steel Tube ◽  
Strength Development ◽  
Fiber Reinforced ◽  
Concrete Filled Steel Tube ◽  
Expansive Concrete ◽  
Short Columns ◽  
Environment Temperature

Abstract. This investigation was done based on the concrete filled steel tube (CFST) winter construction of Ganhaizi Bridge. Steel fiber reinforced micro-expansive concrete (SREC) with high frost-resistance ability, excellent fluidity and good self-compacting ability was prepared. Strength development mode under low temperature was illustrated. Scanning electron microscope (SEM) was used to analyze the morphology features of hydration products at the age of 28 days. It was confirmed that when the content of sodium nitrite was 0.4%, SREC did not frost under -5°C. In addition, SEM showed that ettringite and CSH gels were in good growth state, and concrete structure was very dense. Furthermore, 6 CFST short columns were poured in the winter construction site of Ganhaizi Bridge, and another 27 short columns were cut from emitting slurry pipe filling with concrete emitted from main girder. The bearing capacity of all the CFST specimens was tested when the environment temperature rose to about 25°C. The experimental results indicated that the mechanical performances of CFST specimens with anti-freezing admixture did not exhibit degradation when cast in site under a low temperature and tested at 24.3°C. The concrete presented in this research substantially met the need of Ganhaizi Bridge CFST construction in winter.

Shear response of steel fiber reinforced recycled concrete-filled steel tube columns

2021 ◽  
pp. 136943322110093
Author(s):  
Zhenzhen Liu ◽  
Yiyan Lu ◽  
Shan Li ◽  
Jiancong Liao
Keyword(s):  
Axial Compression ◽  
Steel Fiber ◽  
Steel Tube ◽  
Shear Capacity ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Superposition Method ◽  
Fiber Reinforced ◽  
Concrete Filled Steel Tube ◽  
Shear Span

A comprehensive study of the shear characteristics of steel fiber reinforced recycled concrete-filled steel tube (SRCFST) columns is conducted. 50 CFST stub columns are tested with the variables of steel tube diameter-thickness ratio ( D/t), shear span-to-depth ratio (λ), axial compression ratio ( n), and concrete mix. Two types of cements, three recycled aggregate percentages, three water-cement ratios, and three steel fiber contents are considered in design of concrete mixes. The experimental results show that SRCFST columns present the coincident shear behavior of the ordinary CFST columns. As λ is increased, shear resistance shows a downtrend, while the flexural strength presents an increasing trend. Imposing axial compression or thickening steel tube contributes to an adequate safety margin in plastic period. Based on the contributions superposition method, a predicted model of the shear capacity of SRCFST columns is proposed in consideration of shear-span ratio, axial compression, and self-stress.

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.

Research on Behaviors of Steel Fiber Reinforced Concrete Filled Steel Tube Columns under Axial Load

2010 ◽  
Vol 163-167 ◽  
pp. 596-599 ◽  
Author(s):  
Yi Yan Lu ◽  
Shan Li ◽  
Juan Chen
Keyword(s):  
Reinforced Concrete ◽  
Steel Fiber ◽  
Steel Tube ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Concrete Filled Steel Tube ◽  
Volume Fractions ◽  
Increasing Trend ◽  
Fill Materials

Many in-fill materials are used to improve ductility of concrete filled steel tube (CFST), due to meeting need for a change of seismic design perspective form the previous emphasis on structural strength to emphasis on structural ductility and energy absorption. Among the various in-fill materials, steel fiber is gaining attention in the CFST column. This paper investigates effect of volume fractions of steel fiber to concrete on the behavior of short steel fiber reinforced concrete filled steel tube columns under axial compression. The volume fractions of steel fiber to concrete are 0.6, 0.9 and 1.2%. The results indicate that steel fiber reinforced concrete filled steel tube columns appears to have a significant increasing trend in ductility, and have a slight increasing trend in load capacity with volume fraction of steel fiber to concrete increasing. The failure mode of the composite columns is similar with that of CFST.

Experiment Study on the Frost Resistance of Steel Fiber Reinforced Concrete on the Microstructure

2011 ◽  
Vol 368-373 ◽  
pp. 357-360
Author(s):  
Lei Jiang ◽  
Di Tao Niu ◽  
Min Bai
Keyword(s):  
Reinforced Concrete ◽  
Frost Resistance ◽  
Steel Fiber ◽  
Volume Fraction ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Nacl Solution ◽  
Steel Fiber Reinforced Concrete ◽  
Freeze Thaw ◽  
Damage Rate

Based on the fast freeze-thaw test in 3.5% NaCl solution, the frost resistance of steel fiber reinforced concrete (SFRC) was studied in this paper. On the basis of scanning electron microscope (SEM) and mercury intrusion method, the microstructure and pore structure of SFRC was analysed. The reinforced mechanism of SFRC under the cooperation of freeze-thaw and NaCl solution was discussed. The test results show that adding appropriate amount of steel fibers into concrete can reduce the pore porosity and improve the compactness of concrete. The effects of steel fiber with proper volume fraction can inhibit the peeling of the concrete and reduce its damage rate. The volume of steel fiber on the frost-resisting property of SFRC is obvious.

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