Dear All ,

I had encountered some problems on underground system which need the senior members advise. Please find the question as following .

1. During i covert my model to underground model , can i put the restraint and what is the correct method to input this restraint in underground model? During input the restaint let say G/Z ( From the layout my client going to cast a concrete block on the pipe as represent a G/Z support ) , do i need to remove the bi-linear restraint or retain the bi-linear restraint ?

2. May i know the coefficient of friction between FRP pipe surface and rubber sheet & concrete between rubber sheet .

Please find enclosed is the drawing for reference .

Regards
Glenn

Glenn,

1) After the conversion to the buried model, yes you would go back and edit the buried model, changing restraints as necessary for your concrete blocks. Remember that CAESAR II doesn't know the model is buried. By running your system through the "buried pipe modeler", it is re-meshed and the bi-linear restraints added. This simulates the continuous beam in the soil.

2) Sorry, but those friction coefficients may take some research on your part.

Hi Richard ,

1) For an example i converted the model into buried and now in the editing stage , as you mentioned by edit existing auto defined bi-linear restraint and change the restraint to the concerete block as shown in the attachment. Do it look like a above ground system with simple support due to the absence of the bi-linear support? kindly advise me on the appropriate method to input the concrete blocks into restraint of buried model .

All you need to do is (a) remove the bi-linear restraints at that location and (b) add the anchor.

I am new to CAESAR . I have one question regarding Underground Pipeline.

1)I have done analysis of pipeline under B31.8, But my Expansion stress value result show "No Code Stress check processed". Why is that?

The Code has different requirements for Restrained vs unRestrained pipe.

In CAESAR technical discussion manual , it is written under B31.4 that Expansion allowable is = 0.72*Sy

but in Code B31.4-2009 , it is written in table 403.3.1-1 Allowable expansion stress = 0.90*Sy.

Kindly clarify.

The Specific Code Editions supported by CAESAR II, as well as the Code equations and Allowable equations are listed in the Quick Reference Guide.

I'll have the Technical Reference Manual reviewed.