Adding more Ladders in COMPRESS

[pethi]

hi friends,
this is my first post on this forum. I am a Pressure Vessles engineer. I need to add more than one ladder on a single platform. I could not figure out how to do this?

Is it possible at all in COMPRESS, to add multiple ladders on a single platform? If not how do I get though this?

Thanks,

 

[doct9960]

I think you can add multiple ladders on a single platform. Here's how I do it after modeling the initial platform/ladder:
1. Do the usual Attach >> Platform/Ladder
2. Click the "Copy Existing Platform" button, then select the previous platform that you have modeled. (Data and properties of the previous platform should have been copied)
3. While in the "Add a Platform & Ladder" dialog box modify the following...
- Platform Start Angle = location of additional ladder (e.g. 90[°])
- Platform End Angle = Platform Start Angle + 0.0001 (e.g. 90.0001[°])
- Ladder Angle = location of additional ladder (e.g. 90[°])
- Platform Width = 0.0001
- Grating Weight = 0
- Railing Weight = 0
- Ladder Start to Datum = wherever you want this to be, just as long as it is below the platform elevation
4. Select "Do Not Apply Wind Load"
5. Then click "OK"

By doing this, you take into account the weight of the additional ladder which is added to the total vessel weight, which affects the period of vibration, overturning moments, etc.

I have yet to hear from TomBarsh (owner of this forum) if this is an acceptable method of adding extra ladders.

 

[TomBarsh]

The platform and ladder components are included in COMPRESS so that their weight can be included in the vessel design. COMPRESS will also (optionally) calculate the wind load acting on the platform. COMPRESS does not calculate the wind load on the ladders; wind on ladders should be accounted for by using the "increase in effective vessel OD" input on the Wind Code dialog.

Since the concern for ladders is primarily the effect of their weight on the vessel I see no need for special tricks to force COMPRESS to show the ladder graphically. The weight can easily be accounted for by adding a vertical load at the ladder position. Placing the vertical load at the elevation of the top of the ladder will be conservative.

Note that COMPRESS does not "design" the ladder itself, nor its attachments to the vessel (if desired, the Clip/Lug attachment can be used to determine stresses in the shell resulting from ladder loads).

Tom Barsh
Codeware Technical Support

 

[doct9960]

pethi,

I agree with Tom.

The advantage I see in graphically showing the ladder is that you can visually check if there's a possible interference between the ladder and other vessel parts (e.g. nozzles, stiffening rings, etc.). This gives me a heads up to verify in more detail (using other programs or manual techniques) if there really is an interference.

 

[pethi]

Hi guys,
Thank you very much for your replies Doct & Tom.
Sorry, I got very busy with my work and couldn't find time to reply to you guys. Thanks again for your help.

Tom, my intention in adding the additional ladders is checking them for fouling. As a suggestion to you, if you could implement this feature, it would be very helpful. We don't have to play tricks, as one doc suggested, to do this.

Best regards,