isostatic

[stef_design]

Hey, guys.
I need your help.
I tried to solve this isostatic and with the fem no problem.
I would like to solve it analytically but I can't understand how to calculate cutting and bending moment especially in the beams indicated with the arrow.

if the isostatic was like that of the image 04 no problem. the addition of the side elements of union sends me in confusion.
Thank you.

 

[meccanicamg]

It is not very clear the system of clashes. seems to be stuck in the upper right corner. the beams are united with knots.

the procedure for resolving structures is as follows:
- take the structure as a monoblock, put on the general forces and calculate the reactions to the general bond
- if there's no equation, it means he's hyperstatic.
- in any case it is necessary now to take every single beam and to bring back the forces and to make the balance (or check the knots)

In this way you also get analytical to the fem result... after at least 2 hours of accounts if you don't miss them... so I would say that professionally you don't calculate a structure of this kind anymore.

 

[stef_design]

It is not very clear the system of clashes. seems to be stuck in the upper right corner. the beams are united with knots.

In fact, it is bound with an ink and just (the whole is astounding).
the beams are welded together.

analytically it is simple if the structure was like in the last image (04), but having combined the various beams sends me into difficulty.
example: I only look at the cut in the first section, I have a 100 n strength I expect a 100 n cut instead is 92,16 n?!?
♪

 

[meccanicamg]

Are you sure the value of the fem is right? have you tried with other structures?
there's something that works together if the values are actually right, otherwise... it's a mystery

 

[stef_design]

Are you sure the value of the fem is right? have you tried with other structures?
there's something that works together if the values are actually right, otherwise... it's a mystery

No, no, that's right! ! !
the having introduced the 'trave' element of union of the wings creates a flender moment in the latter and a decrease in the value of the cut on the wings.
Don't you tell me?

the prof quickly told me:
try to 'cut the structure in the middle of the 'new' beam inserted, the system to balance the gap will have to insert a 'new reaction that will create precisely a bending moment and a cut in the 'new' beam

Boo

 

[meccanicamg]

there will be some moment of transport that you run or you have not considered action reaction to the knots....

 

[stef_design]

according to you is more real such a structure

 

[alexlomba87]

Excuse me, can I ask you which fem you're using? Thank you.

 

[stef_design]

Straus7... ciao