Multi-component structural members (eg flitch beams)

[line-weight]

Having had some negative experiences with buggy "structural member" objects a few releases ago, I have avoided using them but I am now testing the water again and trying to use them in VW2021 (I hope to move to 2023 soon).

 

One of the things I want to draw is a flitch beam: metal plate sandwiched between timbers.

 

 

Is there a way of doing this and having the 2 different materials show up in section and in rendered 3d views?

 

I currently manage materials via class.

 

At first I thought maybe I could do this using a "custom" member generated from a symbol. However:

- it looks like symbols used for structural members can only contain one object. is that right?

- in any case, it doesn't seem possible to pull class/textures from objects within the symbol - as a structural member's 3d attributes are defined by the object class or by the "member" and "cover" classes.

 

So, I tried doing it using a steel "member" with timber "cover" which allows me to have two materials. But:

- selecting member type "steel" doesn't actually allow me to choose a flat plate

- I can specify left and right "covers" where I can set the thickness and offset, but it seems they have to be the same depth as the "member" which means I can't create a flitch beam where the timbers and metal plate are different structural depths.

 

Am I missing anything obvious?

 

Or do I basically have to draw this as three parallel structural members?

 

(Another question: is it not possible just to make a simple rectangular section timber joist/rafter using this tool? If I select member type "wood" it insists on creating a kind of timber I-beam. Do I have to create a simple joist by laboriously creating a symbol with the right dimensions and then using member type "custom"?)

 

 

[Tom W.]

16 minutes ago, line-weight said:

(Another question: is it not possible just to make a simple rectangular section timber joist/rafter using this tool? If I select member type "wood" it insists on creating a kind of timber I-beam. Do I have to create a simple joist by laboriously creating a symbol with the right dimensions and then using member type "custom"?)

 

Don't you have Rectangle_Timber shape option?:

 

 

 

[line-weight]

35 minutes ago, Tom W. said:

 

Don't you have Rectangle_Timber shape option?:

 

 

 

Ah!

Thanks!

[Tom W.]

With the flitch beams how will you be using them in the model: a complex network, all different lengths/angles? Or just horizontally?

[line-weight]

23 minutes ago, Tom W. said:

With the flitch beams how will you be using them in the model: a complex network, all different lengths/angles? Or just horizontally?

 

There aren't loads of them but they are all different lengths and some are at funny angles both horizontally and vertically.

 

They'll be connected to regular timber rafters so I wonder if that means it's actually easiest to drawn them as parallel members to try and take advantage of automatic connections between the timber members (something I'm yet to experiment with.

 

A similar question arises with blocked-out steel I-beams...

 

[Tom W.]

I only asked because one option would be to create the flitch beam as a hybrid symbol with a length of 1m then edit the length of the instances in the drawing via asymmetric scaling. I often include two different Top/Plan representations controlled by class: a 'realistic' version + a dashed centre-line version. But you would need a new symbol for each change in angle.

[line-weight]

Next question... am I supposed to be able to connect/trim structural members retrospectively?

 

It appears to be impossible to resize the pitched rafter here such that it is chopped off vertically on the line of the horizontal member - the snap points only want to deal with a square-cut end rather than the vertical cut I've chosen.

 

 

Trying to do it in top-plan doesn't work

 

 

 

Is there any way to tell VW to connect those two members without altering the pitch of the rafter?