F1554 Grade 36, 2 3/4" Diameter Anchor Bolt Capacity 4

[structure_engineer]

Dear Fellow Civil Structural Engineers,

I have to design a foundation for a tall vertical vessels. The anchor bolts designed by the Mechanical Engineers or Vessel Engineers are 2 3/4" diameter F1554 anchor bolts. I am new to this material and thus I need some help to verify if the calculations I did on the anchor bolts capacity are correct and can be used.

AISC Method: =================================================================
Using Section J3.7:
Rn = Fn .Ab
For Ultimate Strength:
where Fn =0.75Fu and for LRFD phi = 0.75
Thus, Rn = phi 0.75Fu Ab = 0.75(0.75)58(pi*2.75^2)/4 = 0.75(0.75)58(5.94) = 193.8 kips

For Allowable Stress Design:
Pa = 0.5(0.75)Ab(Fu) Pg 77 of Steel Design by Segui 5th ed
Pa = 0.5(0.75)(pi*2.75^2/4)(58) = 129.1 kips

As a comparison, the company standard table shows a capacity of 107 kips (Allowable)
The value of 107 kips is obtained as the following:

Rn = Fn Ab Eq. J3-1
Fn = 0.75 Fu
Rn = (0.75 * 58*4.93)/2 (Net tensile area)
Rn = 107.2 kips

I am not sure which is the correct value, the 129.1 kips or the 107.2 kips. I am leaning towards the 129.1 kips as that is based on academic research. The 107.2 kips value is more like based on internal colleague recommendations.

ACI Method: ===================================================================
phi*Nsa = phi*Ase,N *(futa) = 0.75*4.934 *(58 ksi)

Because F1554 Grade 36 is a ductile material, ACI 318-11 D.4.3 says phi = 0.75
phi Nsa = 0.75*4.93*48 = 214.5 kips

Thus, bolt capacity will be the minimum of 193.8 kips or 214.5 kips, for which 193.8 kips governs.

If some of you help to verify the calculations, I could furnish a tabulation of the anchor bolt capacities for the various diameters on here for everyone to use. After all, we need to combine our effort for the good of engineering community for which I believe is one of the purpose of this website. Thank you so much for your attention and effort.

 

[structure_engineer]

My own post:

At the end of the thread, I could post a table showing the various sizes and the various grades of anchor bolts for F1554.

Correction: At the end of the thread, I could post a table showing the capacities of the various sizes and the various grades of anchor bolts for ASTM F1554 anchor rods.

 

[dauwerda]

structure_engineer,

the following is from this thread507-459508:

"As noted in Design Guide 1, AISC utilizes a simplified method that utilizes a modifying factor that relates the tensile stress area directly to the unthreaded area (0.75). As is typical, the simplified process is more conservative than the use of the equation to find the actual effective area of the bolt.

The reason that the simplified method gets more conservative with the large diameter bolts is that once you get to a 2-1/2" diameter bolt, the threads per inch no longer continue to decrease, they stay at 4 threads per inch up to a 4" diameter. The depth of the threads is directly related to the threads per inch (see table 7-17). So as the anchor diameters increase up to 2-1/2" the depth of the threads also increase. However, above 2-1/2" the depth of the threads remain constant, so the percentage of the effective area to the gross area continues to increase for each diameter larger than 2-1/2". The simplified AISC method does not take this into account as it uses a straight 75% factor."

*The reference above to table 7-17 is referring to the AISC Steel Construction Manual.

 

[dik]

HTURKAK:

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Do you feel any better?

-Dik

 

[dik]

Thanks Rabbit, I hadn't considered that.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Do you feel any better?

-Dik

 

[structure_engineer]

I have read through the thread and here is what I came up, for 2 3/4" diameter and 3" diameter:

For 2 3/4" Diameter F1554 Grade 36 Anchor Rods:

For 3" diameter F1554 Grade 36 Anchor Rods:
The capacities for the 3" diameter F1554 Grade 36 Anchor Rods agrees with this thread:
thread507-459508: Different Anchor Rod Tensile Strength between ACI 318 method and AISC method:

 

[dik]

...and for the 2-3/4 bolts using Grade 55 you end up with 251K and 277K in lieu of 194 and 214... an extra 50K 'for almost free'.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Do you feel any better?

-Dik

 

[AskTooMuch]

PIP should have guides how to design vertical vessel foundation including anchor bolts. It may consider rebars in the capacity which you are not considering. Did you do the wind load or it came from the vendor? Did you check if the vertical vessel if rigid?

 

[le99]

The result from LRFD methods corresponded well with the result from ASD, 194/118 = 1.64.

 

[structure_engineer]

Just obtained the confirmation from a major bolt supplier for these 2 3/4" diameter F1554 anchor rods. The cost difference between 12 numbers of F1554 Grade 36 and F1554 Grade 55 anchor rods is $69.24. So it is a very easy decision to make. There is even no need to go up the chain of commands. Thanks very much Mr. dik for the information and the industry "trade secret." And I have the validation of the method of arriving at the anchor rod capacities. Thanks very much guys. This board is a great resource of information. Hopefully we can keep up the brainstorming sessions and keep the jobs local instead of 8990 miles away , through automation and exchange of ideas. Keep on trucking guys.

 

[le99]

If using a higher grade for the same load, the thing you need to watch out for is the failure mode could be brittle unless the bolt size is reduced as well.

 

[structure_engineer]

Definition from ACI 318-14, posted here and hopefully not a violation of copyright:

steel element, ductile—element with a tensile test elonga-tion
of at least 14 percent and reduction in area of at least 30
percent; steel element meeting the requirements of ASTM
A307 shall be considered ductile; except as modified by
for earthquake effects, deformed reinforcing bars meeting
the requirements of ASTM A615, A706, or A955 shall be
considered as ductile steel elements.

Thus, F1554 Grade 55 is still considered a ductile material. But correct me if I am wrong.

I have a question for you, Mr. le99: how did you arrive at the 118 kips capacity for ASD? Could you share the calculations?

 

[Rabbit12]

The ductile failure mechanism needs to consider concrete failure modes as well. Basically, steel yielding needs to be the controlling limit state to satisfy that particular section of the code. There are other ways to satisfy the code such as using the over-strength factor. This is all related to seismic forces and not wind however.

 

[le99]

@Rabbit12 said clearly of my concern.

Great post!

Report
le99 (Civil/Environmental)8 May 22 21:21
Use AISC ASD - A307 bolt, Fu = 60 ksi:

Ab = 3.1416(2.75^2)/4 = 5.94 in2
fa = 20 ksi
Fa = 20*5.94 = 118.8 kips

or, Fa = 0.33Fu*Ab = 0.33(6))(5.94 = 117.6 kips. <----- Governs.

 

[dik]

Elongation of F1554 is better than A307...

That's been my experience... $5 per rod... If you need the anchorage to yield at a lower strength, you can likely reduce the diameter by 1/2"...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Do you feel any better?

-Dik

 

[le99]

dik,

Not to argue which is better, but mind you that the grade should be indicated when specifying F1554.

 

[dik]

Always... and I spec Grade 55S1 all the time... I want it weldable, too.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Do you feel any better?

-Dik

 

[HTURKAK]

MR.DIK,

Apparently this snap taken from the web ,

https://boltport.com/specifications/astm-f1554/

Probably it would be better to look the scope of the Standard Specification for Anchor Bolts, Steel, 36, 55, and 105-ksi Yield Strength ASTM F1554 ..

1. Scope*
1.1 This specification covers straight and bent, headed and headless, carbon, carbon boron, alloy, or high-strength lowalloy
steel anchor bolts (also known as anchor rods). The anchor bolts are furnished in three strength grades, two thread
classes, and in the sizes specified in Section 4......

 

[structure_engineer]

Mr. HTURKAK,

In response to your quote:

"My suggestion will be, ask the design loads ( wind, seismic, operation, test , empty ..) then design the foundation acc. to requirements of ACI 318 .. and no need to questioning the size of the anchor rods. Or you may prefer to provide more info. to get more specific responds.."

That is what we are doing here, to design the anchor rods and foundation to support this tall vertical vessel. First of all, we have to check if the anchor bolts as specified by the ME is good or not. As for some of the suggestion to use a smaller anchor bolts, the lead time to procure the vertical vessel is a long lead time and making changes at this stage will take a lot of effort to make that happen. Then after we verify the anchor bolt size is good, we will then design the pedestals and pile cap to support the foundation loads. In this case, most probably I will have to use two rings of dowels of #7 or bigger, on the outside and inside of the anchor rods to hold the vessel down as the pull out force from each rod is just way too high. The dowels will be hooked into the pile cap.

Thank you all for your time in the response and attention to this thread. I am working on that table...

 

[dik]

HTURKAK... I was going by the contents of the specification... it seems to be somewhat material related, including chemistry...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Do you feel any better?

-Dik