×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

#### Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

# Help! Truss calculation problems

## Help! Truss calculation problems

(OP)
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

### RE: Help! Truss calculation problems

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

### RE: Help! Truss calculation problems

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.

### RE: Help! Truss calculation problems

(OP)

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

### RE: Help! Truss calculation problems

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.

### RE: Help! Truss calculation problems

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

### RE: Help! Truss calculation problems

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.

### RE: Help! Truss calculation problems

(OP)
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.

### RE: Help! Truss calculation problems

(OP)

There are 4 reactions un the image

### RE: Help! Truss calculation problems

?

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.

### RE: Help! Truss calculation problems

#### Quote (ie delete all diagonals, then the solution is easy.)

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

### RE: Help! Truss calculation problems

Something like...

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

-Dik

### RE: Help! Truss calculation problems

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

### RE: Help! Truss calculation problems

Yes dik, I should have considered that.

### RE: Help! Truss calculation problems

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

#### Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

#### Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

#### Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a partâ€™s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!