Help! Truss calculation problems 1

[JoshTheOne]

Please, I need to get the forces and reactions

in the y axis mainly. To later calculate the maximum moment in each horizontal beam. Can someone upload photos of the calculations by hand? The units its in Newton Metter. 1 Metter in x and 0,5metter in y. Thanks

 

[dik]

Are there loads at all nodes? and supports at the 4 corners? It's likely statically indeterminate. Other than second order effects, and self weight, the moments are zero, I would suspect, in particular if the joints are pinned.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[rb1957]

pretty cr@p pictures of your problem. pix cover text, not clear where are the loads.

start where you Know how the loads divide between the members ... at the upper left I assume there's a load in the up/down (the Y) direction. Then there is no load in the horizontal member and only load in the vertical member. Lets go to the next joint down. there can be load in the diagonal member, and this is balanced by load in the horizontal member and the vertical component of this add to the vertical load from the first joint. Remember loads balance at each joint.

the tricky one is the middle row ...but at the top the two diagonal members carry the same load (why? because the horizontal member have zero load, so the horizontal component of the diagonals balance each other).

now it is quite possible that this truss is not statically determinate. There's a test of the truss (something about the number of members and the number of joints)

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[JoshTheOne]

The sap2000 gives me this results. And it have loads in all nodes. It is the structure that will support 6 led screens

 

[rb1957]

you've got out-of-plane loads too ? SAP will solve a redundant problem ... but much harder to hand calc.

I'd start with the check ... is it statically determinate ? (like I said, something about the number of members and the number of joints.)

In any case, if you have out-of-plane loads, the members are now beams (and not traditional truss members) ... quite a more complicated solution.

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[dik]

Does this work? Think of the LED screens as diaphragms...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[rb1957]

ie delete all diagonals, then the solution is easy.

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[JoshTheOne]

Sorry my english Is bad.
This 6 divitions are 6 LED screens
1 LED screen Weight are 18kg x 9.81 are= 176.5. one node Will support the 1/4 of the led screen weight and are some nodes that need to support the weight of 2 1/4 or 4 1/4 of the screen weight.

 

[JoshTheOne]

There are 4 reactions un the image

 

[rb1957]

?

the screens are 2m by 1.5m ? do they mount in the corners (as you're saying) or along that "rod" (0.18m dia ... sounds very big !?)

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[dik]

I thought I'd leave 2... just for initial installation.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[dik]

Something like...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[BAretired]

Sorry my english Is bad.

So are your drawings!

 

[dik]

He's just a rookie... he'll learn. We probably have over 100 years experience between the two of us.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[BAretired]

Yes dik, I should have considered that.

 

[dik]

By mentioning it, hopefully you've given him cause to improve...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik