Dynamic Behavior of Concrete: Experimental Aspects - Dynamic Behavior of Concrete and Seismic Engineering - page 22

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Figure 1.9. Ispra Centre device for big sample testing
To improve understanding of the mechanisms of traction failure and crack
dynamic propagation, a specific device has been developed for effort transmission
and measurement and is included in the large-scale dynamic test equipment (LDTF)
at the European Research Centre Ispra [CAD 01]. To increase the capacity of the
shock transmitted to the specimen at that installation (20 cm-edge cube), the shock is
generated by the violent release of a tight cable. The device (a Hopkinson Bar
Bundle (HBB)) consists of a prismatic Hopkinson bar beam, each bar being
instrumented, which transmits the traction wave to the specimen. Potential helical
reinforcements at both ends of the specimen are eliminated. It is possible to follow
both the opening of a crack across the specimen and the loading transmission
remaining in the not yet broken ligament, by applying a simplifying hypothesis of
wave propagation and load transmission inside the breaking specimen.
Most of the significant results concerning high-speed traction concrete behavior
detailed in section 1.5 were discovered using this installation (Figure 1.9) on quite
large scales.