Spall experiments for the measurement of the tensile strength and fracture energy of concrete at high strain rates

Schuler, Harald; Mayrhofer, Christoph; Thoma, Klaus

doi:10.1016/j.ijimpeng.2005.01.010

Cited by 323 publications

(176 citation statements)

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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%

“…Concerning the data processing, spall strengths and the strain rates were deduced in some modified experimental arrangement, as in the original one, by numerical simulation of the waves superposition process in the specimen, knowing the fracture position experimentally determined [18,20]. In other experimental setups, strain rates were deduced from direct measurements obtained with strain gauges cemented on specimen surface.…”

Section: Discussionmentioning

confidence: 99%

“…To study tensile strength and fracture energy of current concrete (maximum aggregate size of 8 mm, compressive strength of 40 MPa), Schüler et al (2006) [20] used a incident bar and notched and unnotched concrete specimens of 74.2 mm diameter with respective length of L b = 5500 mm and L s = 250 mm, Fig. 3.…”

Section: Advances In the Experimental Techniquementioning

confidence: 99%

“…By means of this setup developed by Schuler et al [20], dynamic spall experiments at strain rates varying between 140 and 180 s −1 were conducted on notched and unnotched cylindrical specimens of strain hardening cement-based composites (SHCC) [22]. The SHCCs are characterized by very high binder and relatively high fiber volume contents in finely grained matrix composition (0.2 mm maximum aggregates size) with fly ash.…”

Section: Advances In the Experimental Techniquementioning

confidence: 99%

“…The loading rate and applied load were derived from the strain measurements on the steel bar and the specimen. The transmitted pulse was determined via the incident compressive pulse recorded with carbon gauges embedded in the concrete specimen and the dynamic Young modulus E dyn (deduced from the wave velocity C 0 as done by Schuler et al [20]), and calculated using the transmission time between the different strain gages locations distributed near the contact interface with the bar and along the rear half of the specimen intended to capture the failure zone. Assuming an uniaxial wave propagation, the transmitted tensile pulse was reconstructed theoretically, whereas the dynamic tensile strength was deduced from strain measurements just outside the analytically (and via exploring tests) predetermined failure zone.…”

Section: -P3 Epj Web Of Conferencesmentioning

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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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Advances In the Experimental Techniquementioning

confidence: 99%

Section: Advances In the Experimental Techniquementioning

confidence: 99%

Section: -P3 Epj Web Of Conferencesmentioning

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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In situ measurements of impact-induced pressure waves in sandstone targets

Hoerth

Schäfer

Nau

et al. 2014

J. Geophys. Res. Planets

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In the present study we introduce an innovative method for the measurement of impact-induced pressure waves within geological materials. Impact experiments on dry and water-saturated sandstone targets were conducted at a velocity of 4600 m/s using 12 mm steel projectiles to investigate amplitudes, decay behavior, and speed of the waves propagating through the target material. For this purpose a special kind of piezoresistive sensor capable of recording transient stress pulses within solid brittle materials was developed and calibrated using a Split-Hopkinson pressure bar. Experimental impact parameters (projectile size and speed) were kept constant and yielded reproducible signal curves in terms of rise time and peak amplitudes. Pressure amplitudes decreased by 3 orders of magnitude within the first 250 mm (i.e., 42 projectile radii). The attenuation for water-saturated sandstone is higher compared to dry sandstone which is attributed to dissipation effects caused by relative motion between bulk material and interstitial water. The proportion of the impact energy radiated as seismic energy (seismic efficiency) is in the order of 10 À3 . The present study shows the feasibility of real-time measurements of waves caused by hypervelocity impacts on geological materials. Experiments of this kind lead to a better understanding of the processes in the crater subsurface during a hypervelocity impact.

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Handbook for Blast‐Resistant Design of Buildings

Dusenberry¹

2010

130

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Limit of Liability/Disclaimer of Warranty: While the publisher and the author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specificall disclaim any implied warranties of merchantability or fitnes for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable for your situation. You should consult with a professional where appropriate. Neither the publisher nor the author shall be liable for any loss of profi or any other commercial damages, including but not limited to special, incidental, consequential, or other damages.For general information about our other products and services, please contact our Customer Care Department within the United States at (800) 762-2974, outside the United States at (317) 572-3993 or fax (317) 572-4002.Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books. For more information about Wiley products, visit our web site at www.wiley.com.

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Spall experiments for the measurement of the tensile strength and fracture energy of concrete at high strain rates

Cited by 323 publications

References 7 publications

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

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

In situ measurements of impact-induced pressure waves in sandstone targets

Handbook for Blast‐Resistant Design of Buildings

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