Summary of tube action -Very good in strength and stiffness Flange part of square tube takes 75 total bending moment Web part of square tube takes 90%shear force -Horizontal and vertical subsystems work together to achieve tube actionSummary of tube action -Very good in strength and stiffness - Flange part of square tube takes 75 % total bending moment - Web part of square tube takes 90% shear force -Horizontal and vertical subsystems work together to achieve tube action