Dynamic Behavior of Concrete: Constitutive Models - Dynamic Behavior of Concrete and Seismic Engineering - page 58

- crater formation; this is the extremely damaged zone with fragment ejection on
the impacted side;
- “tunneling”; the projectile progresses through the wall while causing big shear
strains and compaction inside concrete;
- scabbing; at the output of the projectile, traction stresses lead to an ejection of
fragments.

40

crater

tunneling

20

0

scabbing

-20

-40

0 20 40 60 80

Section 270° - 90° (cm)

Figure 2.3. Concrete slab perforated by a projectile (from [BUZ 98])

2.1.3. Ejection of fragments

When the dynamic loading causes projections of fragments of the concrete
structure, we can classify them into three types.

The scabs are formed due to concrete traction failure according to a process
which will be detailed in section 2.3. If we assume a perfect brittle failure, we can
estimate the ejection speed from equation [2.1], which also gives usual values for
concrete:

V
U

10
2, 200

MPa
kg

½
°

r

3

VU cV / m |

V

1.5 ms /

¾
°

[2.1]

r e e

c 3, 000 m / s

¿

e