Ductile and Brittle materials
Materials ability to undergo significant plastic deformation under tensile stress before rapture called ductile properties of materials. In other words if materials ductile, materials stretch under tensile load. The ductile materials is Steel, Aluminum, copper etc.
Brittle materials break without significant plastic deformation under tensile stress. Also called sudden failure. Brittle material absorb little energy prior to rapture. The brittle material is glass, Plain concrete, cast iron etc.
In this figure you can observe materials (a) break without losing its cross-section area means materials is brittle. This type of materials fail suddenly without any notice.
Failure of material (b) shows, it’s a ductile materials. Ductile materials reduced its cross section before rapture.
Material (c) it’s called a complete ductile materials.
This ability to deform help structure to resist seismic force. When the seismic load acted on building ductile structure perform well compare to other type of structure.