Steady‐State and Multiple Cracking of Short Random Fiber Composites

Li, Victor C.; Leung, Christopher Kin Ying

doi:10.1061/(asce)0733-9399(1992)118:11(2246)

Cited by 1,042 publications

(297 citation statements)

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“…As a type of high performance fiber-reinforced cementitious composite (HFRCC), ultra high toughness cementitious composite (UHTCC) was developed under the guidelines of criteria for the design of multiple cracking strain hardening composites proposed by Li and Leung (1992). UHTCC is often referred to as engineered cementitious composite (ECC) (Li and Kanda, 1998) or strain hardening cement-based composite (SHCC) (Boshoff and van Zijl, 2007).…”

Section: Introductionmentioning

confidence: 99%

Rate dependence of ultra high toughness cementitious composite under direct tension

2016

J. Zhejiang Univ. Sci. A

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Ultra high toughness cementitious composite (UHTCC) usually shows strain hardening and multiple cracking under static tension loads. In practice, structures could be exposed to high strain rates during an earthquake. Whether UHTCC can maintain its unique properties and provide high structural performance under seismic loading rates largely determines whether it can successfully fulfil its intended function. To determine the rate dependence of UHTCC, uniaxial tensile tests with strain rates ranging from 4×10 −6 s −1 to 1×10 −1 s −1 were conducted with thin plates. The experimental results showed that UHTCC had significant strain hardening and excellent multiple cracking properties under all the rates tested. The ultimate tensile strain lay in the range of 3.7% to 4.1% and was almost immune to the change in strain rates. The rate of 1×10 −3 s −1 seemed to be a threshold for dynamic increase effects of the first crack tensile strength, elastic modulus, ultimate tensile strength, and energy absorption capability. When the strain rate was higher than the threshold, the dynamic increase effects became more pronounced. The energy absorption capability was much higher than that of concrete, and the average ultimate crack widths were controlled below 0.1 mm under all rates. Several fitting formulas were obtained based on the experimental results.

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Section: Introductionmentioning

confidence: 99%

Rate dependence of ultra high toughness cementitious composite under direct tension

2016

J. Zhejiang Univ. Sci. A

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“…2. Superior tensile strain hardening response of ECC can be engineered by tailoring the composite ingredients with the aid of micromechanically based formulations [5,7,[10][11][12]. This paper reviews and presents some of the most important durability properties of the SHFRCC materials, such as crack width control, permeability in cracked state, corrosion resistance, freeze-thaw resistance, performance in hot environments, shrinkage cracking resistance, and combined mechanical and environmental loads.…”

Section: Introductionmentioning

confidence: 99%

“…ECC is ultra ductile cement based composites reinforced with short random fibres (metallic and/or nonmetallic) which exhibit strainhardening and multiple-cracking behaviors in uni-axial tension as well as in bending [2-5, 7-8, [10][11][12]. It is a strain hardening type of fibre reinforced cementitious composite that is microstructurally tailored based on micromechanics [3][4][5][10][11][12]. ECC typically has tensile strain capacity of more than 3%, with spacing between multiple cracks at saturation less than 3 mm and maximum crack width less than 100 micrometers.…”

Section: Introductionmentioning

confidence: 99%

A review on durability properties of strain hardening fibre reinforced cementitious composites (SHFRCC)

Shaikh

Mihashi

2007

Cement and Concrete Composites

100

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Abstract:This paper reviews and presents various durability properties of strain hardening fibre reinforced cementitious composites (SHFRCC). Published research results show that, due to its tight crack width properties compared to ordinary concrete and ordinary fibre reinforced concrete, SHFRCC significantly resists the migration of aggressive substances in to the concrete and improves the durability of reinforced concrete (RC). It is also reported that, due to the strain hardening and multiple cracking behaviours, SHFRCC meets the tight crack width limits for durability of RC structures proposed by different design codes. Based on the reviewed durability properties it is argued that SHFRCC materials can be used in selected locations of RC structural members to improve their overall durability performances.

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“…More recently, further extension to randomly oriented discontinuous fiber reinforced composites have been presented [3,4]. Upon satisfying these conditions described in the above mentioned micromechanical models, the ultimate tensile strains of the composites are usually improved by two order of magnitude ( e.g.…”

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confidence: 99%

“…Load reversal point is set at cod (505 m in this case) which corresponds to the peak load of a fiber with its embedded length equal to L f /2. This corresponds also to the maximum composite strength [3,11]. Material parameters of the composite used are listed above and =0.15 MPa is estimated from the maximum bridging stress.…”

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confidence: 99%

Buckling of bridging fibres in composites

Wu¹,

Matsumoto²,

Li³

1994

J Mater Sci Lett

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In brittle materials such as concrete and ceramics, fiber reinforcement has been widely accepted as an effective way of improving their strength and toughness. In addition, a notable pseudo strain-hardening phenomenon can contribute to a significantly enhanced ductility of the composite when adequately designed fiber system is used.This condition was first proposed by Aveston et al. [1], and later extended by Marshall et al. [2] for continuous aligned fiber reinforced brittle matrix composites. More recently, further extension to randomly oriented discontinuous fiber reinforced composites have been presented [3,4]. Upon satisfying these conditions described in the above mentioned micromechanical models, the ultimate tensile strains of the composites are usually improved by two order of magnitude ( e.g. see [5], [6], [7]). The total fracture energy reaching 35 kJ/m 2 was also reported for a 2% polyethylene fiber reinforced cement paste [8]. This kind of ductile fracture resembles metal instead of brittle materials.The pseudo strain-hardening behavior of fiber reinforced brittle matrix composites is associated with multiple cracking, and results from adequate stress transfer capability of bridging fibers. Studies are typically conducted under monotonic tensile loading only. In reality, composites are usually subject to cyclic loads. As a * submitted for publication in J. Mater. Sci. Lett. 1993 2 preliminary report of an ongoing research on the cyclic behavior of pseudo strainhardening cementitious composites, we present an initial finding on buckling of bridging nylon fibers across fracture planes in a cement composite after complete unloading intension. An analytic model is also proposed to account for this buckling phenomenon.Type I Portland cement, silica fume and superplasticizer were used to form the cement paste with water /cementitious ratio of 0.27. Discontinuous nylon fibers (L f =21 mm, d f =25 m, and E f =5.2 GPa) were used to reinforce the paste at a volume fraction of 2 %. Tensile coupon specimens of size 304.8 x 76.2 x12.7 mm were prepared and tested under direct tension in a servo hydraulic tester. Detailed mix proportions and testing procedure can be found elsewhere [9]. Tensile stress-strain curves were recorded. Optical microscope with 50 times magnification was used to examine the bridging fibers after the specimen was completely unloaded.The stress-strain curve is shown in Fig. 1 where four peaks are identified, corresponding to four multiple cracks occurred within a length of 200 mm. After reaching the ultimate load, the main crack opened up continuously with descending load carrying capacity while other cracks were unloaded. Examination of these closing cracks using a microscope reveals both buckled fibers as well as straight fibers across the crack surfaces. This is shown in Fig. 2. It is clearly demonstrated that a portion of the fibers underwent buckling. In the following, an analysis is made to examine this buckling phenomenon.It is possible to explain why some of the nylon fibers buc...

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Steady‐State and Multiple Cracking of Short Random Fiber Composites

Cited by 1,042 publications

References 19 publications

Rate dependence of ultra high toughness cementitious composite under direct tension

Rate dependence of ultra high toughness cementitious composite under direct tension

A review on durability properties of strain hardening fibre reinforced cementitious composites (SHFRCC)

Buckling of bridging fibres in composites

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