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GCivil3-Newcomer
3-Newcomer
September 23, 2022
Solved

Solve Block - Biaxial Bending Moment

  • September 23, 2022
  • 2 replies
  • 1937 views

Hello, I've reached a point on my calculation where I'm stumped and I'm hoping one of you can help. I'm admittedly not the most knowledgeable when it comes to solve blocks. I'm attempting to find the biaxial bending moment of the column/pedestal and cannot get the solve block to find the correct answer. I've tried different iterations of the solve block where I've defined every constraint, but I've wittled it down for this worksheet. Essentially, I'm looking for a point where the axial force and moment ratios are equal in the column. I've attached my worksheet. Any guidance you guys would have would be appeciated!

Best answer by Werner_E

The problem with your solve block is, that P.u, P.n, M.ux, etc. all already are constant values. Prime won't look back to see how these values depend on c.ped and alpha. The solve block would need these to be functions of c.ped and alpha to be able to iterate and find a solution.

Unfortunately this would mean that you have to change your worksheet massively. Every value which is now calculated and depends on c.ped or alpha has to be turned into a function. As far as I see that means starting with

Werner_E_3-1663948214424.png

 

and then

Werner_E_2-1663948171765.png

and

Werner_E_4-1663948368422.png

etc.  (I found your sheet quite difficult to edit because you place all your calculations into limiting text regions)

As you see you can evaluate the functions using the value you had assigned for alpha beforehand. Of course you could name the function differently, e.g. getxy1(alpha) and then assign xy1:=getxy1(alpha) if you need to do so. But every calculation the later solve block should depend on has to use the functions, not the constant values.

A good method to see if you got all occurrences and changed them to function use is to disable the regions in section 3.5.1.2. No function definition below should show an error.

 

2 replies

L
LucMeekes23-Emerald IV
23-Emerald IV
September 23, 2022

The constraints in your solve block are not functions of the variables whose values you want to find: alpha and c.ped. Hence it cannot find values for them.

Prime does NOT look up in the sheet to see how you may have defined any of the P and M values, it wants to see P.u(alpha, c.ped) etc. as appropriate. Or you can write out the full expressions ( involving those alpha and c.ped ) into the constraints section.

 

Success!
Luc

G
GCivil3-NewcomerAuthor
3-Newcomer
September 23, 2022

Thank you for the help! Unfortunately I'm still a little confused. Would I be defining the P & M values (in terms of alpha & c.ped) as guess values or would those just be additional constraints? 

W
Werner_E25-Diamond IAnswer
25-Diamond I
September 23, 2022

The problem with your solve block is, that P.u, P.n, M.ux, etc. all already are constant values. Prime won't look back to see how these values depend on c.ped and alpha. The solve block would need these to be functions of c.ped and alpha to be able to iterate and find a solution.

Unfortunately this would mean that you have to change your worksheet massively. Every value which is now calculated and depends on c.ped or alpha has to be turned into a function. As far as I see that means starting with

Werner_E_3-1663948214424.png

 

and then

Werner_E_2-1663948171765.png

and

Werner_E_4-1663948368422.png

etc.  (I found your sheet quite difficult to edit because you place all your calculations into limiting text regions)

As you see you can evaluate the functions using the value you had assigned for alpha beforehand. Of course you could name the function differently, e.g. getxy1(alpha) and then assign xy1:=getxy1(alpha) if you need to do so. But every calculation the later solve block should depend on has to use the functions, not the constant values.

A good method to see if you got all occurrences and changed them to function use is to disable the regions in section 3.5.1.2. No function definition below should show an error.

 

    G
    GCivil3-NewcomerAuthor
    3-Newcomer
    September 23, 2022

    Thanks for the explanation! It was a massive rework, but I believe I got it to work!

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