Device for testing concrete under impact tensile loading and lateral compression

Weerheijm, J.; Reinhardt, Hans W.

doi:10.1016/0029-5493(91)90028-g

Cited by 39 publications

(51 citation statements)

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“…Weerheijm [29] concluded that the fracture energy is strain-rate-independent since experiments showed relatively constant fracture energy up to strain rates of 23 s -1 , but more recent studies ( [30-32]) indicate that also the fracture energy is strain-rate-dependent. Schuler [30] has proposed a relation between the dynamic increase factor for the fracture energy for concrete, defined as the ratio between the dynamic fracture energy and the static fracture energy, and the crack-opening velocity, as shown in …”

Section: Plain Concretementioning

confidence: 99%

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Comparative numerical studies of projectile impacts on plain and steel-fibre reinforced concrete

Nyström

Gylltoft

2011

International Journal of Impact Engineering

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The enhanced energy absorption characteristics of fibre-reinforced concrete, compared to plain concrete, has in experimentally studies been shown to improve the projectile resistance and motivate its increased usage in protective structures. However, the high cost of undertaking experiments and the high parameter variation and dependency of the experimental setups and results, respectively, make it difficult to draw generic conclusions of how the addition and increased amount of fibres affects the local damage caused by projectile impact, which motivates the use of numerical simulations to study this. The numerical hydrocode AUTODYN was used in a qualitative study of how the addition of different amounts of fibres, modelled as different post-crack relations, influence the depth of penetration and crater formation on the front and rear face of a concrete target. Fibres added to the concrete mix had a minor influence on the depth of penetration while the crater size on both front and rear faces of the target decreases. The crack propagation beyond the crater on the front face was also reduced when fibres were added to the concrete. An increased amount of fibres in the concrete showed no effect on the size of the front-face crater, but led to further decreased size of the crater on the rear face of the concrete cylinder. It is concluded that the scabbing crater can be reduced in size and prevented by usage of fibre-reinforced concrete even if the depth of penetration is only slightly less than to penetration depth in plain concrete.Keywords: Numerical simulation, Projectile impact, Steel-fibre reinforced concrete, Penetration 1.Introduction A projectile impact may cause local and global damage to a concrete structure. Global damage consists of flexural deformations, which, unlike local damage, may cause structural failure. Local damage may cause spalling and crushing of concrete on the front face and scabbing on the rear face of the target, together with projectile penetration into the target or even full penetration (i.e. perforation) of the target [1,2]. Different variables have been proposed to measure local damage, such as depth of penetration, perforation and scabbing thickness or ballistic limit (i.e. the minimum velocity at which the projectile penetrates the target) in plain or reinforced concrete [2].Researchers have experimentally studied the behaviour of fibre-reinforced concrete under impact loading and observed a significant increase in the overall resistance to local damage when compared to plain concrete [3][4][5][6][7][8][9][10][11]. However, the structural behaviours of targets subjected to impact are complicated, depending on material factors as well as test-condition factors [6], which vary between the reported experiments and therefore make it difficult to draw generic conclusions of the effect of fibres and how it changes with different amounts of fibres in the concrete.The local damage parameters in concrete are often estimated by using empirical, semi-empirical or purely analytical eq...

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Section: Plain Concretementioning

confidence: 99%

“…Weerheijm [29] concluded that the fracture energy is strain-rate-independent since experiments showed relatively constant fracture energy up to strain rates of 23 s -1…”

Section: Plain Concretementioning

confidence: 99%

Comparative numerical studies of projectile impacts on plain and steel-fibre reinforced concrete

Nyström

Gylltoft

2011

International Journal of Impact Engineering

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“…Several analytical, experimental and numerical studies demonstrated that the evolution of micro-cracks cannot occur arbitrarily fast due to inertia effects [26][27][28]. Thus, if damage is used to describe microcracking , its evolution has to be retarded in case of high strain rates, i.e.…”

Section: Rate-dependent Damage Modelmentioning

confidence: 99%

Simulation of dynamic behavior of quasi-brittle materials with new rate dependent damage model

Pereira

Weerheijm²,

Sluijs³

2016

Proceedings of the 9th International Conference on Fracture Mechanics of Concrete and Concrete Structures

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Abstract. In concrete often complex fracture and fragmentation patterns develop when subjected to high straining loads. The proper simulation of the dynamic cracking process in concrete is crucial for good predictions of the residual bearing capacity of structures in the risk of being exposed to extraordinary events like explosions, high velocity impacts or earthquakes.As it is well known, concrete is a highly rate dependent material. Experimental and numerical studies indicate that the evolution of damage is governed by complex phenomena taking place simultaneously at different material scales, i.e. micro, meso and macro-scales. Therefore, the constitutive law, and its rate dependency, must be adjusted to the level of representation. For a proper phenomenological (macroscopic) representation of the reality, the constitutive law has to explicitly describe all phenomena taking place at the lower material scales. Macro-scale inertia effects are implicitly simulated by the equation of motion.In the current paper, dynamic crack propagation and branching is studied with a new rate-dependent stress-based nonlocal damage model. The definition of rate in the constitutive law is changed to account for the inherent meso-scale structural inertia effects. This is accomplished by a new concept of effective rate which governs the dynamic delayed response of the material to variations of the deformation (strain) rate, usually described as micro-inertia effects. The proposed model realistically simulates dynamic crack propagation and crack branching phenomena in concrete.

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“…For instance, a modified Charpy impact test [1], as in the conventional Charpy impact machine used by the metallurgists, where a swinging pendulum is allowed to strike a specimen in its path thereby transferring momentum and causing high stress rates. Other significant impact tests include the split Hopkinson pressure bar test [2,3], in which the specimen is sandwiched between two elastic pressure bars and stress waves are generated by using a drop weight or a projectile. Two techniques mentioned above are not convenient for testing the impact resistance of reinforced concrete or concrete structures owing to the dimensions of the sample, thus, a drop weight impact test is always used to study the impact response of the concrete structures [4][5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

A new drop weight impact machine for studying the fracture behaviour of structural concrete

Zhang

Ruiz

2008

WIT Transactions on the Built Environment

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This paper describes the main characteristics of a new drop weight impact machine that has been specifically designed for studying the dynamic mechanical behaviour of structural concrete samples. Such equipment has been used to generate simple and measurable fracture processes under moderate to fast loading rates, as opposed to blast chambers, which produce complicated crack patterns that are difficult to analyze. The machine consists of two main parts, the mechanical structure and the data acquisition system. The former is just a hammer, guided by two robust columns, which can impact the specimen with energy up to 7860 J. The latter consists of piezoelectric force sensors, accelerometers and an optical fibre photoelectric sensor plus oscilloscopes and signal conditioners. The paper also presents the results of some preliminary tests that show the sensitivity of the work of fracture to the loading rate.

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Device for testing concrete under impact tensile loading and lateral compression

Cited by 39 publications

References 1 publication

Comparative numerical studies of projectile impacts on plain and steel-fibre reinforced concrete

Comparative numerical studies of projectile impacts on plain and steel-fibre reinforced concrete

Simulation of dynamic behavior of quasi-brittle materials with new rate dependent damage model

A new drop weight impact machine for studying the fracture behaviour of structural concrete

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