Tensile failure of concrete at high loading rates: New test data on strength and fracture energy from instrumented spalling tests

Weerheijm, J.; Doormaal, J.C.A.M. van

doi:10.1016/j.ijimpeng.2006.01.005

Cited by 218 publications

(103 citation statements)

References 2 publications

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“…A possible explanation may be that the presence of tensile cracking prior to pure Mode II is being delayed, therefore affecting the radial stress in the ligament. This, furthermore, could be explained by a higher tensile strength observed in concrete like materials when subjected to high strain rate tensile loading, that has been reported in literature by several authors [8][9][10].…”

Section: Discussion Of the Dynamic Experimentsmentioning

confidence: 52%

Influence of loading-rate and steel fibers on the shear strength of ultra high performance concrete

Lukić

Forquin

2015

EPJ Web of Conferences

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Abstract. The paper describes quasi-static and dynamic experimental methods used to examine the confined shear strength of an Ultra High Performance Concrete, with and without the presence of steel fibers in the concrete composition. An experimental setup was created to investigate the concrete shear strength under quasi-static loading regime using a hydraulic press Schenk while dynamic shear strength was characterized by subjecting concrete samples to dynamic loading through a modified Split Hopkinson Pressure Bar. Both methods are based on a Punch Through Shear (PTS) test with a well-instrumented aluminum passive confinement ring that allows measuring the change of radial stress in the shear ligament throughout the test. Firstly, four equally distributed radial notches have been performed in order to deduce the radial stress by suppressing a self-confinement of the sample peripheral part. However, by analyzing the strain gauge data from the confinement ring, it has been noticed that these were apparently insufficient, especially for fiber-reinforced samples, resulting in subsequently practicing eight radial notches through the sample peripheral part. The results obtained from both procedures are reported and discussed.

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Section: Discussion Of the Dynamic Experimentsmentioning

confidence: 52%

Influence of loading-rate and steel fibers on the shear strength of ultra high performance concrete

Lukić

Forquin

2015

EPJ Web of Conferences

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“…The accelerometer is a miniature device encapsulated in a small lightweight aluminum alloy box (less than 10 mm 3 in volume and weighing approximately 2.5 g) allowed to measure peak accelerations of 600 000 m/s 2 . Glued on the rear face of specimen, it allows, as in Schuler et al [20] and Weerheijm et al [23] tests, to measure the pullback velocity and next to calculate the dynamic resistance of the specimen knowing the wave velocity C 0 and the Young's modulus E dyn of the concrete tested in the case of a 1-D analysis. The laser extensometer based on interferometry technique, combined with reflectors made of thin tiles of aluminium alloy glued on the rear face of the specimen, allow to directly obtaining the particles velocity.…”

Section: Discussionmentioning

confidence: 99%

“…Even in this case, it will probably fail at the fracture instant without capturing the complete strain pulse. To overcome this difficulty, strain rates were in this case indirectly estimated from signals measured by the strain gauges located near the failure surface [23,24]. The question that arises naturally with this kind of processing is the level of precision of these data knowing that the value of net tensile pulse and the strain rate resulting from superposition process of the transmitted compressive wave can changes considerably along very short travelled distances.…”

Section: Discussionmentioning

confidence: 99%

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Advances in experimental assessment of dynamic tensile strength of concrete by the spalling technique

Brara¹

2015

EPJ Web of Conferences

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Abstract. An experimental method to test concrete in dynamic tension by spalling with a Hopkinson bar as loading and measuring tool was developed in 1999. The dynamic strength of concrete specimen and strain rate were indirectly derived from an accurate data processing of the signals measured on the Hopkinson bar surface. This method suggested by late Prof. Klepaczko, allowed for reaching the highest strain rate reported in literature for which an intriguing tensile strength increase was highlighted. This simple and efficient technique has been adopted by many researchers around the world. Some significant improvements in terms of definition and reproducibility of the incident loading pulse travelling along the bar and direct and/or contactless measurements on concrete specimens have been introduced. The very high rate sensitivity of concrete tensile strength was corroborated by the additional experimental data obtained with this experimental technique during the last fifteen years. IntroductionThe most important phenomenon highlighted by the experimentation on concrete dynamics undertaken during the last decades is the rate sensitivity of the material, which means that its mechanical properties -notably the tensile strength, the Young's modulus, the Poisson ratio, the critical strain -depend on the applied loading rate. The phenomenon of increase of tensile strength with the loading rate, observed in the early sixties of the last century has been recognized as the "rate effect", and is typically represented as a dynamic increase factor (DIF), i.e., the ratio of dynamic to quasi-static strength versus strain rates. Globally, the rate dependency of concrete tensile strength can be subdivided into two regimes; a regime starting from the quasi-static range of strain rates up to about 1.0 s −1 with moderate rate effects and a regime with extensive rate effects for higher strain rates for which a DIF increased from 2 to about 7 [1]. The highest strain rates were essentially obtained with techniques based on the spalling phenomenon. Spall is defined as the ejection of fragments of a material specimen from the opposite side from which the specimen was impacted and/or impulsively loaded.The earliest experiment at very high strain rate reported by the literature was conducted on large plain concrete specimens (51 mm diameter and 838 mm length) impacted at one end by a steel sphere. The signals were recorded by means of strain gauges cemented on concrete specimen surface. In these tests, DIFs of 2.5 and 6 for 2.0 s −1 and 23 s −1 were respectively highlighted [2].This considerable strength increase was also observed about two decades later for large concrete instrumented wall panels (4,57 m × 1,65 m), each which were mounted on the side of a rectangular box reaction structure, loaded a Corresponding author: ahmedbrara@hotmail.com by surface explosion of TNT charge [3]. Pullback velocity of the ejected fragments measured during the test by means of high speed photography (10 3 pictures/s) allowed estimating the spall stren...

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“…In the case of high-rate tensile loading, the ultimate uni-axial tensile strength may be as much as 5 to 7 times higher than the static tensile strength [21], and even though the effect on the ultimate compressive strength is less pronounced it may still be more than doubled [22]. It has recently also been indicated that the fracture energy is strain-rate-dependent [23][24][25].…”

Section: Concrete Behaviour Under Static and Dynamic Loadingmentioning

confidence: 99%

Numerical studies of the combined effects of blast and fragment loading

Nyström

Gylltoft

2009

International Journal of Impact Engineering

128

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The well-known synergetic effect of blast and fragment loading, observed in numerous experiments, is often pointed out in design manuals for protective structures. However, since this synergetic effect is not well understood it is often not taken into account, or is treated in a very simplified manner in the design process itself. A numerical-simulation tool has been used to further study the combined blast and fragment loading effects on a reinforced concrete wall. Simulations of the response of a wall strip subjected to blast loading, fragment loading, and combined blast and fragment loading were conducted and the results were compared. Most damage caused by the impact of fragments occurred within the first 0.2 ms after fragments' arrival, and in the case of fragment loading (both alone and combined with blast) the number of flexural cracks formed was larger than in the case of blast loading alone. The overall damage of the wall strip subjected to combined loading was more severe than if adding the damages caused by blast and fragment loading treated separately, which also indicates the synergetic effect of the combined loading.

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Tensile failure of concrete at high loading rates: New test data on strength and fracture energy from instrumented spalling tests

Cited by 218 publications

References 2 publications

Influence of loading-rate and steel fibers on the shear strength of ultra high performance concrete

Influence of loading-rate and steel fibers on the shear strength of ultra high performance concrete

Advances in experimental assessment of dynamic tensile strength of concrete by the spalling technique

Numerical studies of the combined effects of blast and fragment loading

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