topic Truss Forces in Robot Structural Analysis Forum

Truss Forces

Anonymous — Sun, 25 Feb 2018 18:12:17 GMT

Hi there,

I am currently doing a truss design for a 40m truss with point loads of 71.08KN at 0.5m across the whole length, however when i have ran the calculations the max force within the internal members is approx 10MN for compression and tension,

Could someone please help me as I am unsure whether these internal forces are correct and if they are could someone suggest a way in order to reduce them

Many Thanks

2032165b

Re: Truss Forces

Simau — Sun, 25 Feb 2018 19:53:59 GMT

Hi @Anonymous

Just increase the height of the truss.

Re: Truss Forces

Rafacascudo — Sun, 25 Feb 2018 22:37:38 GMT

You should reconsider your truss geometry . All your sections chord or diagonals are the same. This is how it will look if really is built

What´s the point of choosing a truss like this?

Easier would be building a single girder!!!

Try starting with 45 degrees diagonals

Re: Truss Forces

Anonymous — Mon, 26 Feb 2018 11:20:48 GMT

Thanks Rafa

I chose that geometry because the point loads are at 0.5m spacing so I chose those diagonals to go between points loads

Is it possible to make the diagonals greater even thought there will be no members going between the nodes of the point loads?

Re: Truss Forces

Rafacascudo — Mon, 26 Feb 2018 11:29:36 GMT

Hard to say without knowing what kind of structure is this and from where do these 71Kn loads come. Maybe the the best engineering solution will be a regular girder as I suggested before.

Re: Truss Forces

Anonymous — Mon, 26 Feb 2018 11:31:27 GMT

The 71KN are from the reactions of beams, is it possible to therefore add a UDl onto the truss as a bar load?

Many Thanks

2032165

Re: Truss Forces

Rafacascudo — Mon, 26 Feb 2018 11:33:51 GMT

Sorry , what is UDl ??

Re: Truss Forces

Anonymous — Mon, 26 Feb 2018 11:35:31 GMT

Sorry a uniformly distributed load across the top of the truss,

Is there a way I can add this instead of having the point laods

Thanks

Re: Truss Forces

Rafacascudo — Mon, 26 Feb 2018 11:56:49 GMT

Of course . You just have to change the structure type from "truss" to "2d frame" so you can apply this type of load along the bar lenght, and then consider other forces different from only axial tension and compression.

Re: Truss Forces

Anonymous — Mon, 26 Feb 2018 12:29:18 GMT

Thanks for your help Rafa