Correct Answer - Option 3 : Semi-compact section
Explanation
Various types of the section are as follows:
1. Plastic - Cross sections, which can develop plastic hinges and have, the rotation capacity required for the failure of the structure by formation of a plastic mechanism, are called plastic sections. The stress distribution for these sections is rectangular.
2. Compact - Cross sections, which can develop the plastic moment of resistance, but have inadequate plastic hinge rotation capacity for formation of a plastic mechanism before buckling classed as compact sections. These cross-sections may develop fully plastic stress distribution across the entire cross-section but do not have adequate ductility. The stress distributions for these sections is rectangular.
3. Semi-compact– Cross sections, in which the extreme fiber in compression can reach yield stress but cannot develop the plastic moment of resistance due to local buckling are called semi-compact or non-compact sections. These sections are used in the elastic design and the stress distribution for such sections is triangular.
4. Slender section – Cross sections in which the elements buckle locally even before the attainment of yield stress are classed as slender sections.
