Hiperstatic structure

[Lepetit]

Hello all,

I have a question about hiperstatic structures, someone knows how to calculate a hiperstatic structure like in the attached picture? All the examples I have are in a continuous beam.

Thank you in advanced.

Cheers

 

[JStephen]

"Statically indeterminate" is the term that comes to mind. You'll wind up with several equations and several unknowns if doing it by hand, but it's just a matter of slogging through the details.

 

[Lepetit]

Yes JStephen,

I mean Statically Indeterminate. I know that the equation system would be "huge" but I need first to make a approximation calculation by hand before to implement in the Analysis program. Do you know any method to do that?

thank you

 

[frv]

It wouldn't be "huge".

Statically indeterminate structures this small are pretty easy to solve by hand. Use any of a number of approaches in any structural analysis book. The only somewhat complicated thing is keeping track of of all the variables.

 

[MiketheEngineer]

Since you have only one "fixed" reaction - you know it will take all the vertical and moment forces. Then maybe just sum moment around the each of the others assuming the other one doesn't exist. This will most likely give the "maximum" forces. If you can live with those - then you are done!!

If not - a much more specific analysis will be required. Think RISA or whatever??

 

[PicoStruc]

It is a typical hyperstatic structure problem,

You need two more equations other than summation of forces (X & Y) and moment (Z).

To do so, remove two restrain, and use energy theorem using unit forces to solve this problem. Check it is in every structure textbook.

 

[JStephen]

From the figure, it looks like the two lower horizontal members would have no moments anywhere, just axial load?
Call the top member and the vertical member under P "the ell".
Call the middle member #2.
Call the lower member #3.
Equating the horizontal deflection in the ell at member #2 to the axial deflection in member #2 gives you one equation.
Equating the horizontal deflection in the ell at member #3 to the axial deflection in member #3 gives you a second equation.
Summing moments about the top left corner gives you a third equation.
That leaves you three equations with the unknowns being N2, N3, and M1. In this case, calculating deflections is the tedious part, solving three equations will be fairly simple.
Having solved them, sum forces horizontally to find N1 and sum forces vertically to find V1.

It would quite likely be a reasonable assumption to say that the axial deflection in #2 and #3 is negligle, but that doesn't give a lot of simplification.

 

[Lepetit]

Thank you all very much,

I will also check and structure book I have found in a library.

Cheers