{{:wikipaom2019:rollbar_compared_stiffness_discussion.gif|commento_risultati}}

Deformed and undeformed shapes are plotted, plus the bending moment.
An equal imposed displacement load condition is applied to each case.

An equal imposed deflection is imposed at the top-left corner, stiffness has been evaluated based on the associated reaction force.

The three frame structures stiffness is reported below:
  * $b/a=1/5$:  $k=7.29k_\mathrm{ref}$
  * $b/a=1/1$:  $k=5.60k_\mathrm{ref}$
  * $b/a=5/1$:  $k=3.38k_\mathrm{ref}$
where $k_\mathrm{ref}$ is the stiffness of the single upright member, taken as a reference.

Beam cross section is uniform along the frame, and very slender.
{{ :wikipaom2019:rollbar_compared_stiffness_discussion.mfd |(MSC.Marc model)}}