Question

The number of possible independent mechanisms for the portal frame shown in the figure is

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

The correct option is C 3

The number of independent mechanisms (n) is related to the number of possible plastic hinge location (h) and the number of degree of redundancy (r) of the frame by the equation.
Here, $h=5$ and $r=2$
$\therefore$ Number of independent mechanism $\left(n\right)=(h-r)=(5-2)=3$