topic Re: Two perpendicular frames in Robot Structural Analysis Forum

Two perpendicular frames

HoshangMustafa — Mon, 29 Apr 2024 18:53:15 GMT

Hi all

Please find the attached file.

Is my approach correct in modeling the column at grid F2? How can this column support the smaller frame? Or should I use two columns (with perpendicular orientations) rather than one column? Or should I use rigid links with one column (on grid F2) to transfer the loads from the smaller frame using bracket? Or should I extend bar 159 to the column on grid F2?

Re: Two perpendicular frames

Simau — Tue, 30 Apr 2024 20:08:22 GMT

Hi @HoshangMustafa

The model is correct regarding the small farm at grids F2 and G2.
The beam and column_1 bar types must be reconfigured because the buckling lengths are not correct.
Why do you use claddings as there is no load on them?
I suppose that stability in the Y direction is ensured by the concrete structure, so no vertical bracing is necessary.

Re: Two perpendicular frames

HoshangMustafa — Wed, 01 May 2024 05:54:13 GMT

Hi @Simau

You wrote:

The beam and column_1 bar types must be reconfigured because the buckling lengths are not correct.

Can you elaborate more on this?

Why do you use claddings as there is no load on them?

The model is made using Frame generator module. I supposed that ARSA would apply wind loads on the claddings, then distribute it to frame members. Am I correct?

I suppose that stability in the Y direction is ensured by the concrete structure, so no vertical bracing is necessary.

This concrete structure is intended to model a masonry structure. Besides, there would be masonry between the columns in the Y direction as infills ensuring stability in that direction.

Re: Two perpendicular frames

Simau — Wed, 01 May 2024 10:53:29 GMT

@HoshangMustafa

Do not to take into account the masonry structure in the model to avoid problems relating to the steel-masonry junction.

Also pay attention to the masonry on the facades which will transmit wind load, so use cladding. Use vertical bracings, because the masonry will not transmit efforts due to poor steel-masonry connections.

Apply the loads directly to these claddings instead of applying them to the bars.

Use a different bar type for each kind of column and beam. example, for main frame columns you’ll use

We are far from the use of Robot, but rather on steel structure design.

Re: Two perpendicular frames

HoshangMustafa — Thu, 02 May 2024 22:29:35 GMT

Hi @Simau

Apply the loads directly to these claddings instead of applying them to the bars.

I wanted to investigate the steel structure during construction. So applied the loads to the bars.

Use a different bar type for each kind of column and beam. example, for main frame columns you’ll use

This option is not available with ARSA 2019

We are far from the use of Robot, but rather on steel structure design.

Your previous posts (in italic) concern Robot e.g., cladding, Auto Buckling length coeff.

What about my concerns in OP, does your Message 2 mean these 3 points aren't correct:

1- How can this column support the smaller frame?

2- Or should I use two columns (with perpendicular orientations) rather than one column?

3- Or should I use rigid links with one column (on grid F2) to transfer the loads from the smaller frame using bracket? Or should I extend bar 159 to the column on grid F2?

Re: Two perpendicular frames

Simau — Fri, 03 May 2024 10:27:11 GMT

Hi @HoshangMustafa

This option is not available with ARSA 2019

Of course it exists

1- How can this column support the smaller frame?

Yes it can, as soon as the 2 members are connected

2- Or should I use two columns (with perpendicular orientations) rather than one column?

Not necessary, but if you want you can use a compound member column

3- Or should I use rigid links with one column (on grid F2) to transfer the loads from the smaller frame using bracket? Or should I extend bar 159 to the column on grid F2?

What about my concerns in OP

What do you mean by OP

Re: Two perpendicular frames

HoshangMustafa — Fri, 03 May 2024 11:28:22 GMT

This is displayed with my office ARSA:

Your option in step #4 doesn't appear here.

Yes it can, as soon as the 2 members are connected

As you can see in my model, I used compound member column W8x48 S8x23 on grid F2 and G2. How can S8x23 support the smaller frame while W8x48 would support the main frame. This was my intent.

Not necessary, but if you want you can use a compound member column

It seems you didn't notice I already used compound member column in my model at grid F2 and G2.

What do you mean by OP

OP: original post

Re: Two perpendicular frames

Simau — Fri, 03 May 2024 11:40:28 GMT

Your option in step #4 doesn't appear here.

Try again and click on step3 then 4

As you can see in my model, I used compound member column W8x48 S8x23 on grid F2 and G2. How can S8x23 support the smaller frame while W8x48 would support the main frame. This was my intent.

The compound member will act as a single column and and will support both members.

Re: Two perpendicular frames

HoshangMustafa — Fri, 03 May 2024 13:53:10 GMT

Hi @Simau

Try again and click on step3 then 4

I followed all steps as seen in the screenshots, but without success.

The compound member will act as a single column and and will support both members.

In practice S8x23 (supporting the smaller frame) will be shorter than W8x48 (supporting the main frame). Please have a look at my model. How one can consider this in modeling?

Re: Two perpendicular frames

Simau — Fri, 03 May 2024 14:32:41 GMT

@HoshangMustafa

I followed all steps as seen in the screenshots, but without success.

It's weird!

In practice S8x23 (supporting the smaller frame) will be shorter than W8x48 (supporting the main frame). Please have a look at my model. How one can consider this in modeling?

As i said before, compound column will act as a single member #26.
Upper frame will be supported at node #32 and lower one at node #128

Re: Two perpendicular frames

HoshangMustafa — Fri, 03 May 2024 20:12:27 GMT

Hi @Simau

It's weird!

Please try on your computer to display the Buckling Diagrams dialog that I uploaded in message 7. If you could do it, then it seems I'm not following your steps from 1 to 4 in message 3.

As i said before, compound column will act as a single member #26.
Upper frame will be supported at node #32 and lower one at node #128

If so, I wouldn't use compound column. I would use W8x48 only.

Re: Two perpendicular frames

Simau — Sat, 04 May 2024 11:11:22 GMT

@HoshangMustafa

If so, I wouldn't use compound column. I would use W8x48 only.

This is not a good idea, because the flange of S28x23 will be used to connect the lower frame, otherwise how will you connect the lower frame to the W8x48 web

Look at this video to create a member type

(view in My Videos)

Re: Two perpendicular frames

HoshangMustafa — Sat, 04 May 2024 22:37:46 GMT

Hi @Simau

This is not a good idea, because the flange of S28x23 will be used to connect the lower frame, otherwise how will you connect the lower frame to the W8x48 web

Did you mean that ARSA would use S28x23 only to connect the lower frame?

Look at this video to create a member type

It seems you didn't follow message 11:

Please try on your computer to display the Buckling Diagrams dialog that I uploaded in message 7. If you could do it, then it seems I'm not following your steps from 1 to 4 in message 3.

I mean

Please try on your computer to display the same Buckling Diagrams dialog that I uploaded in message 7. If you could do it, then it seems I'm not following your steps from 1 to 4 in message 3.

Re: Two perpendicular frames

Simau — Sun, 05 May 2024 11:30:45 GMT

Hi @HoshangMustafa

Did you mean that ARSA would use S28x23 only to connect the lower frame?

Please look at the image below for the 2 options with an without S28x23 and choose what option you prefer. Keep in mind that compound bar will provide more stiffness to both frames and better connetion design:

Please try on your computer to display the same Buckling Diagrams dialog that I uploaded in message 7. If you could do it, then it seems I'm not following your steps from 1 to 4 in message

Please follow steps in my video

Re: Two perpendicular frames

HoshangMustafa — Sun, 05 May 2024 18:40:21 GMT

Hi @Simau

S28x23 web should be connected to W8x48 flange and not the way you showed in compound option, so the rafters of the smaller frame would be bearing on S28x23 and the rafter of the main frame would be bearing on W8x48 and the smaller frame would be outside the main frame.

Please follow steps in my video

Why you don't follow my post:

Please try on your computer to display the same Buckling Diagrams dialog that I uploaded in message 7. If you could do it, then it seems I'm not following your steps from 1 to 4 in message

Re: Two perpendicular frames

Simau — Sun, 05 May 2024 19:23:49 GMT

Hi @HoshangMustafa

That's not what is in your model

Why you don't follow my post:

It's difficult to follow, please circle in red the steps you have followed

Re: Two perpendicular frames

HoshangMustafa — Sun, 05 May 2024 19:43:06 GMT

Hi @Simau

That's not what is in your model

Sorry my mistake. The compound section should be S10x25.4 W8x48. S10x25.4 web should be connected to W8x48 flange, so the rafters of the smaller frame would be bearing on S10x25.4 and the rafter of the main frame would be bearing on W8x48 and the smaller frame would be outside the main frame.

It's difficult to follow, please circle in red the steps you have followed

Please try on your computer to display the same Buckling Diagrams dialog that I uploaded in message 7. If you could do it, then it seems I'm not following your steps from 1 to 4 in message.

Re: Two perpendicular frames

Simau — Sun, 05 May 2024 20:29:46 GMT

Hi @HoshangMustafa

I admit that it is difficult to follow you. Could you do a hand sketch

Please try on your computer to display the same Buckling Diagrams dialog that I uploaded in message 7. If you could do it, then it seems I'm not following your steps from 1 to 4 in message.

I am on Robot 2024, indeed we don't have the same figures. You may click on 2