Dynamic Behavior of Concrete: Constitutive Models - Dynamic Behavior of Concrete and Seismic Engineering - page 57

“plate-plate” test [LEV 96], which gives the pressure level necessary for dynamic
loading compaction.
2.1.1.5. Scabbing caused by wave reflection on the non-loaded side
Scabbing of reinforced concrete elements results from fracture due to traction
perpendicular to their free surface. This phenomenon is linked to wave propagation
inside the material. Typically, for a 20 cm thick concrete wall, the wave arriving
time onto the “free open surface” is about 0.6 P s. From experience, we can notice
that the surface ejected by direct scabbing corresponds to the cover between the last
layer of the reinforcement and the free surface.
2.1.1.6. Bending of the structure
The wall's bending phenomenon is slower, as it depends on the structure more
than on the local behavior of the material. It important to note that shear failure of
slabs due to shear loads are possible in dynamics, whereas it is extremely rare under
static loading.
2.1.1.7. Influence of the reinforcements
Reinforced concrete reinforcements have an effect on the development of macro-
cracks. The cracks, which separate blocks during failure, preferably meet with the
reinforcements (Figure 2.2). Within structures specially designed to withstand
impacts, so-called “lacing” reinforcements limit chip projections.
Figure 2.2. Shape of fragments on a plate submitted to a shock tube (from [PON 95])
2.1.2. Perforation
Perforation of a concrete wall generally reveals three areas (Figure 2.3):