Blodgetts "Design of Welded Structures" question
Blodgetts "Design of Welded Structures" question
(OP)
I have just got a copy of this book and have a question that I hope someone can help me with. I am trying to design a water tank. I think that I need a stiffener around the top. On page 6.5-2 of this book, Blodgett shows an example "Tank with top edge stiffener". Nowhere in the formulas is the geometry of the stiffener considered.
Question 1. How do I know what the I for the stiffener should be?
Question 2. He says that "The modified tank now satisfies the condition 5A on table 1. My copy does not show condition 5A. Does he mean 4C?
Thanks for any help
Question 1. How do I know what the I for the stiffener should be?
Question 2. He says that "The modified tank now satisfies the condition 5A on table 1. My copy does not show condition 5A. Does he mean 4C?
Thanks for any help






RE: Blodgetts "Design of Welded Structures" question
RE: Blodgetts "Design of Welded Structures" question
I have the same book and the same "error". I think 4C is correct.
>How do I know what the I for the stiffener should be?
I think the assumption is that the I of the stiffener is large compared to the I of the tank, as long as you use a "respectable" size section, relative to the tank, hence it probably doesn't matter what the I of the stiffener is.
-- drej --
RE: Blodgetts "Design of Welded Structures" question
Going to the next example, "Considering Plate Section as a Beam", Blodgett calculates the maximum deflection on page 6.5-5 except for the (12) in the numerator and the (.5)^3 in the denominator of the calculation.
Are these two values part of the I=bh^3/12? If so, should the I not be the total I for both the plate and the stiffener?
I think he also makes another error in the equation. The constant .0625 should be .00652 per the equation 3Da on page 8.1-8.
RE: Blodgetts "Design of Welded Structures" question
In these examples, the stiffener determination is not shown. What you have to do is determine the reaction at the top of the plate (the little arrow reaction symbol shown in condition 4C, Table 1). This would be a uniform load of X lbs/ft. This then would be a simple beam design spanning from tank wall to tank wall over the 120".
RE: Blodgetts "Design of Welded Structures" question
So I think that his formula on page 8.1-8 is incorrect and should be .0652 - not .00652.
RE: Blodgetts "Design of Welded Structures" question
"So I think that his formula on page 8.1-8 is incorrect and should be .0652 - not .00652."
I thought that it should have been .00652 because he has the same equation for ?(max) on page 6.4-2, figure 3, condition B and on page 8.1-8.
Also, in the formula for condition 3Da on page 8.1-7, the ? max = .01304WL^3/EI. This equates to the same as the formula on page 8.1-8... Unless I am missing something, I think the equation on 8.1-8 is correct and there is a typo in the example on page 6.5-5 in the ? max problem.
Do you agree with what I have pasted below?
Thanks.
RE: Blodgetts "Design of Welded Structures" question
So the correct number is 0.00652.
Your hand calc is what I originally did - but with the erroneous 0.1304 number from the 2rd Edition of the AISC LRFD Manual...which was wrong and corrected by errata in the third edition LRFD.
RE: Blodgetts "Design of Welded Structures" question
"In these examples, the stiffener determination is not shown. What you have to do is determine the reaction at the top of the plate (the little arrow reaction symbol shown in condition 4C, Table 1). This would be a uniform load of X lbs/ft. This then would be a simple beam design spanning from tank wall to tank wall over the 120". "
Just so that I understand what you are saying to do.. On page 8.1-8, formula 3Da, I should solve for R1. This uniform load could then be used in Equation 3B on page 8.1-7 to solve for M(max) and delta max. This will tell me what the I should be for the stiffener around the top.
Thanks for your help.
RE: Blodgetts "Design of Welded Structures" question
RE: Blodgetts "Design of Welded Structures" question
RE: Blodgetts "Design of Welded Structures" question
Can anyone tell me where to find 5Da or 5Db?