Light Framing Truss in Parts ? Lateral Load transfer mechanism? 1

[CFS339]

Dear All,

Is it a correct design approach? i.e.

There is a cold formed steel structure 30m x 33m. 30 meter truss is provided but the truss is supported at every 6 meters with a lattice columns. As bending moment should be avoid on the Cold formed steel columns so can I convert 30 Meters truss into 5 parts, each part individually supported on two columns and for vertical loads at as a simply supported truss ( Truss parts are connected just to columns at the base but not to each other). But while Analyzing it for Lateral loads , CAN we assume that these side by side parts of the truss are gonna transfer lateral load to the adjacent truss part.Please be noted that these truss parts are just kept side by side and only connected from the bottom track to the top of lattice columns. And act as a complete Truss assembly? What do u suggest is it a correct approach?

Regards

RWB

 

[hokie66]

I am not going to try to assist you with cold formed steel design, as it is very complex and beyond my scope. But if you can fix the base of the trussed columns as your sketch shows, you can use moment connections at the top as well. This is not putting moment on the individual members, but rather transferring axial forces from truss to truss.

 

[gobsmacked]

I think Hokie is right that you are out of your depth. Although Hokie wants to terminate his discussion I think it wrong to leave you high and dry. I will close my contribution with some general remarks. (1) You as an individual and you as the firm you work for should recognise when you are going beyond your experience and seek professional assistance with people experienced in this type of work. (2) You need to practice writing illustrated 'structural stability statements' that identify the load paths AND the actions employed in getting all your loads into the ground. You may then appreciate the application of the triangulation principle in framing, especially required for light gauge structures like this one. (3) A fellow engineer I know used light gauge steel structures like yours for emergency structures after an earthquake. They got it all up, but the next morning they found it swayed over and was a pile of wreckage. This is what will happen if you build your structure like your drawing S3. It is a mechanism and on no account should you build it like that. (4) The principle of bracing is remarkably simple in two dimensions, but in practice in 3 dimensions, you often need a bit more, just to ensure a structure is 'well-behaved' rather than 'just adequate'. I will leave you with those thoughts and close my contribution to this thread.

 

[CFS339]

Dear Hokie & gobsmacked,

Thank you to both of you for your kind assistance.