The ductility of the columns is assessed by the use of a ductility index (DI) as following (Lin, Tsai 2001):
The ductility index, Eqn (12), is also used to study the effect of steel wall thickness on the ductility of the columns.
Beaumont and others define an adimensional parameter called ductility index
used to establish the impact performances of different materials with similar geometries.
The ductility index was calculated according to Eq.
The Charpy impact strength, the perforation energy and the ductility index of long fiber reinforced composite are much higher than in case of the short fiber reinforced one.
It is also clear that, strengthening with externally bonded GFRP strip in different layers to tension face of precracked and uncracked beams result in reduce the beam ductility index
(ratio between deflection at failure and its deflection at yield) than that of the control beam.
The ductility index of the n*-notched foamed samples was slightly higher than that of unfoamed samples, whereas the opposite is true with the bs- and unnotched foamed samples.
Finally, the ductility index of the supersaturated samples remained the same as that of the neat samples.
The ductility index of the blank samples was essentially the same as that of the unfoamed samples.
The trends of the fracture energy and ductility index are similar to those reported above for the polystyrene matrix.