Today let’s talk about how member behaviours are classified as flexural dominated and shear dominated.
There is an term(beta) which is basically ratio of flexural stiffness to shear stiffness.
Please refer the screenshot on the left for it.
To simplify this ratio depends on poisson ratio, span/depth ratio and end condition.
With the increase in span to depth ratio, the flexural stiffness reduces, hence beta will reduce. In this case, the behaviour would be flexural dominated or flexural mode.
And the vice versa, that is span to depth ratio is reduced (say deep beams), shear mode will be dominant.
The load transfer mechanism can be varied from flexure(Bernoulli Beam) to shear(strut and tie) or vise versa simply by altering span by depth ratio relatively.
Check the screenshot on the right, how bending moments change by altering the span to depth ratio😊.
As always more insights or corrections are welcomed from the community.
To all the budding structural engineers out, softwares are good to learn, but it’s waste if you don’t understand the fundamental structural behaviour. So keep reading, miles to go 😊.
Source:Earthquake Behaviour by CVR Murthy
Murthy
