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A307 vs A325 bolt
2

A307 vs A325 bolt

A307 vs A325 bolt

(OP)

About 3 years ago while casting the upper part of a building. I asked in this forum whether to use A307 or A325 bolt for future roofing addition. Someone recommended A307 over A325.. I couldn't find the thread pertaining to it and the exact reason but it's something along the line of the A325 being high strength and more brittle in connections.. so I used A307. But reviewing their strength now.. I seemed to regret choosing A307.

I'd like to know what application do you exactly use the A307 bolt over A325? Does the A325 require special torqueing in the nuts or longer embedment length.. is there special reason to use the A307?

RE: A307 vs A325 bolt

I've never used A307 for anything requiring loads enough to actually go through and calculate it. The "brittleness" of A325 and A490 bolts is really a misnomer. A325 and A490 bolts can be bent into pretzels before they'll start to fracture.

Professional and Structural Engineer (ME, NH)
American Concrete Industries
www.americanconcrete.com

RE: A307 vs A325 bolt

(OP)
Are you saying the A307 is not usually used as anchor bolts (Edit: can't be used on anything with metal plates). then what is it usually used for? can't it be part of any bolts to support any roof?

RE: A307 vs A325 bolt

Wood uses A307 exclusively. I'll sometimes use it for little crap jobs like a new roof top unit needs a support frame. Loads are small.

RE: A307 vs A325 bolt

(OP)
how weak is the A307 really.. what is its yield strength? I think it's close to Grade 40 rebars with yield strength of about 36 ksi (grade 40 rebars is 40 ksi).. so if the load can be taken by grade 40 rebars.. then the A307 may take the load too (4 ksi less)?

RE: A307 vs A325 bolt

I use them on residential and light commercial.
Probably alot cheaper then A325

RE: A307 vs A325 bolt

(OP)
XR.. you mean on wooden residential and light commercial? because it seems they only use it for wood.. has anyone actually use this on metal plates on concrete?

RE: A307 vs A325 bolt

they don't define its yield, just rupture.

quote from Salmon:
"Bolts of low-carbon steel designated ASTM A307 are the least expensive bolt. They may not, however, produce the least expensive connection since more are required for a particular connection. Their primary use is in light structures, secondary or bracing members, platforms, catwalks, purlins, girts, small trusses, and similar applications in which the loads are primarily small and static in nature. Such bolts are also used as temporary fitting-up fasteners in cases where high-strength bolts, rivets, or welding may be the permanent means of connection."

quote from Breyer:

".... Without a published value for yield strength, there is a conecptual problem in using the yield limit model with ASTM A307 bolts. As a practical matter, A307 bolts have performed satisfactorily in the past, and these fasteners must have a reasonable Fy. The tables in the NDS are based on Fyb = 45ksi, which is generally thought to be a conservative value of yield strength for A307 bolts."

RE: A307 vs A325 bolt

I use it only on wood. It is my understanding it is a lot cheaper than A325, and come in longer lengths which would be required for wood. The wood bearing governs so often that the capacity of the steel connection is rarely seen, not always but in my experience with heavy timber and light framing the wood governs or i add bolts, never increase bolt strength like steel framing.

RE: A307 vs A325 bolt

(OP)

Ok thanks guys. I'm now convinced the A307 is poor. There is still hope. I found out I can use post installed Hilti chemical bolts with tested 75.3 ksi. see: https://www.us.hilti.com/anchor-rods

RE: A307 vs A325 bolt

I have never seen A307 or A325 bolts specified for concrete anchors. Older drawings often times specified A36. Today, F1554 is the recommended specification for anchor bolts. There are 3 grades of F1554: Gr. 36, Gr. 55, and Gr. 105. An A307 bolt has material strengths similar to F1554 Gr.36.

The A307 bolts may be OK. You need an engineer to verify the demand does not exceed the capacity.

RE: A307 vs A325 bolt

In our office we usually specify F1554 Gr 36 for our cast-in anchor rods. The reason for using the lower grade anchor Is that if the anchor is damaged or mis-located low it may be possible to weld an extension to the rod (Where using the higher yield Gr 55 and Gr 105 you would need to specify that the anchors are of a weldable alloy). this may have been why you used A307?I think you can weld to A307 because it is not heat treated. I don't believe you can weld to A325 without loosing the steels temper.http://www.eng-tips.com/

RE: A307 vs A325 bolt

So if A307 has a 36 ksi yield, what is the difference between it and F1554 Grade 36? Is it the consistency of the alloy or different manufacturing processes?

RE: A307 vs A325 bolt

In the A307 spec, there was a Grade C for anchor bolts made from A36 material, now replaced by the F1554 Gr. 36.

RE: A307 vs A325 bolt

I don't see any difference in the mechanical properties of the two. What is wrong with using A307 if it meets the capacity requirements?

RE: A307 vs A325 bolt

XR250..nothing that I am aware of.....

RE: A307 vs A325 bolt

So it's just a certification thing. Makes sense.

RE: A307 vs A325 bolt

(OP)
So it's unanimous the A307 is unreliable? Also when one of you says A307 is used for light trusses, how light is light? The base plate it's connecting to just support 2 pcs of 18 foot rafters (size w8x21) coming from sides.. like this.

X--------W---------X

where the "-------" is the 18 foot w8x21 rafter, the base plates on the columns above (the W and X) with A307 bolts support the rafter.. is this loading low or big? The rafter just supports typical purlins and light roof material sheet.

This picture is the top of the column:



(or see http://www.pbase.com/image/161555922 if no image shows up)

RE: A307 vs A325 bolt

upk....how on earth did you get that A307 is unreliable from the comments above? Please read them again...that's not what they say or even imply!

A307 used in most building construction will have an ultimate strength of 60 ksi....as someone noted, 45ksi is a reasonable yield.

A307 is commonly used where high strength bolts (A325 and A490) are not necessary. There is nothing wrong with A307 bolts provided you have done an appropriate analysis of the loads and apply appropriately. That's no different than designing with any other bolt.

RE: A307 vs A325 bolt

Quote (upk)

is this loading low or big?

Can you specify the loading? I'm confused by this thread and your line of questioning. Who specified these bolts in the first place? Are you responsible for determining if these bolts are adequate? I mean this with all due respect - based on this thread, I don't think you're qualified to make these decisions.

RE: A307 vs A325 bolt

(OP)
Ron.. many said they never use A307 and some use it only on wood.. so I presume they are so poor.. i'll add hilti chemical anchors on the column top...

the designer who specified the A307 already resigned and the contractor is hurrying to put the metal plates.. so I have less than 12 hours to get all the Hilti chemical bolts and install them myself noting of the breakout, pryout, and tension cones failure mode with coordination from Hilti engineers...

RE: A307 vs A325 bolt

Whatever you interpreted to mean the A307 bolts are "poor", forget it. Read Ron's post and take it as gospel.

Until very recently, A307 was the most commonly used grade for anchor bolts. Perhaps it still is.

High strength anchor bolts should only be used when you really need the strength. They are less ductile, more expensive, and generally less available.

What size are your existing A307 anchor bolts and what force do they need to take? Until you can answer that question, you have no basis to change anything.

RE: A307 vs A325 bolt

A307 is standard for steel to steel bolted connections in our office unless higher strength are required.

RE: A307 vs A325 bolt

A307 was used for cast-in-place concrete anchors until recently. It's yield stress is assumed as 36 ksi.

Now, the common cast-in-place anchor is F1554, where the yield stress is specified as 36 ksi.

Do not use A325 for anchors. If a higher yield stress is required, there are higher grades of F1554. I think I remember them being 55 ksi, and 105 ksi.

RE: A307 vs A325 bolt

(OP)


How much can the end of the A307 be hammered before it loses strength? After the contractor measured the hole positions by putting the blank plates on top (drawing with pencil around the cast-in-anchor end see picture above) and after we bring it to shop to be drilled.. the drilled holes can't aligned with the anchors exactly... so can we hammer the A307 end (with a nut put into it and hammered to avoid thread damage)? Hole drilled is 17mm.. anchor is 16mm

RE: A307 vs A325 bolt

I would not let them hammer the bolt at all. Drill the correct spacing, and use oversized plate washers.

How much moment are you trying to resist at this connection, that will help us all out give you better advice.

RE: A307 vs A325 bolt

(OP)

Quote:

I would not let them hammer the bolt at all. Drill the correct spacing, and use oversized plate washers.

How much moment are you trying to resist at this connection, that will help us all out give you better advice.

Only very few moment.. it's just to support rafter at middle.. it's mostly on shear when rafters flex during seismic.



RE: A307 vs A325 bolt

So what are the calculated values, Mu, Vu?

RE: A307 vs A325 bolt

(OP)
actually the designer ignored the poor A307 that's why he made the base plate smaller enough not to use it.. but contractor use bigger plate that uses the A307.. and designer said no problem... So we'll end up with 8 bolts per 500x500mm base plate.

Isn't it A307 is supposed to be soft.. can it suffer fracture by just little blow to align with drilled holes?

RE: A307 vs A325 bolt

Yes, its poorly soft. Dont hammer it. Drill the holes out, and use bigger plate washers.

RE: A307 vs A325 bolt

(OP)

If hole is bigger.. and the structure sways back and forth.. then the increased hole may even cause enough inertia and momentum to even strain the bolt.. no?

RE: A307 vs A325 bolt

im pretty sure if your structure sways that far, the bolt is the least of your worries.

Where is this structure being built?

RE: A307 vs A325 bolt

(OP)

Seismic zone.

In grade 40 rebars.. you can bend it more to be used as stirrups.. the grade 60 rebars can just fracture.. in the case of the A307.. it's grade 37.. won't it be flexible at all? why?

RE: A307 vs A325 bolt

Thanks. Good luck with your structure.

RE: A307 vs A325 bolt

(OP)
Thanks for this tips about the A307 being poorly soft jrisebo. I just called the contractor now and demand they don't hammer the bolt because it's "poorly soft" and instead make the hole bigger like you said on at least one of the holes and use washer.

About the designer. He was just 22 years ago and no field experience. When I asked him details like this last time. He said his job was only to produce rebars output ratio and it is up to the contractor to implement it. So I know I need to first check the background of the designer before giving him any project.

RE: A307 vs A325 bolt

I posted this in your other post - but A307 was used for years as anchor bolts (rods actually).
You would never use A325 for embedded anchor bolts.

Currently F1554, Grade 36 (or 55) is the proper anchor rod specification.

Check out Eng-Tips Forum's Policies here:
FAQ731-376: Eng-Tips.com Forum Policies

RE: A307 vs A325 bolt

(OP)

In the Philippines. All use high strength A325 in wide flange columns.. they have to let the fabricators produce them for any length. This is according to my contractor and designer. They ask why I used such lowly A307. This is what prompted me to ask all this. I went to a hardware this morning. Their A325 are only short and like a big screw. Maybe when the A325 are made into long anchors.. they become another name? What is the new name or is it still A325?

RE: A307 vs A325 bolt

@upk

A325 are high strength bolts, they cannot be used as anchors

per AISC, preferred anchor bolts are F1554 gr 36, Gr 55

They cannot be called with different name to make it anchors. A325 chem composition is different from F1554

RE: A307 vs A325 bolt

I still call out A307 on occasion because there's one location nearby where, for some reason, finding all thread F1554 rod without getting it threaded to order is hard (or the contractor in that location is just bad at finding things and likes paying steel fabricators to custom fab anchor rods?). So for small, non-critical projects there I'll often call out A307.

There's absolutely nothing wrong with A307 as an anchor rod, especially when you're so close to the edge of the concrete that you're unlikely to be able to develop the strength of the rod anyway.

RE: A307 vs A325 bolt

Just to clarify, and then I am finished with this thread, A307 is NOT "POORLY SOFT", whatever that means. I think jrisebo was being facetious.

You can knock A307 bolts around a bit, but a better solution is to ream (read drill) out the holes in your base plate to give you reasonable tolerance. Were you able to get the epoxy out?

The existing A307 bolts in the corner of the columns, directly adjacent to the corner reinforcement, will take a lot more load than your drilled in anchors.

RE: A307 vs A325 bolt

My turn.....

Quote (hokie66)

Read Ron's hokie66's post and take it as gospel.

upk...you are obviously not a structural engineer. While I admire your attempts to get things right, you do not have the technical background to adequately implement the advice you've been given here. Please get some competent engineering involvement in this and other similar projects before someone gets hurt or killed. You mentioned that the design engineer was 22 years old. If that is true I would certainly not want him designing critical portions of a structure without more senior engineering overview and supervision.

A307 bolts are fine for anchor bolts. Stop bucking that premise. A325 is a BOLT! It is not a threaded rod and does not serve as an anchor bolt. Yes, it looks like a screw.....a big one.

RE: A307 vs A325 bolt

(OP)
i'll go to the structural company and visit the president now.. one of his team asked why I didn't use A325 as metal plate anchor bolt as this was supposed to be standard for high strength in the industry.. that was why they ignored the lowly A307.. at least I know how to ask them later.. many thanks for all the assistance...

RE: A307 vs A325 bolt

(OP)
Ok.. had a meeting with the most senior structural engineer of one of the country's biggest structural firms (who did the original building and roof design).. they showed me their manual of high strength steel they used in design of anchor bolts which they specify as A325.


(or see http://www.pbase.com/techroof/image/161568806 if it won't load)

Upon calling the suppliers.. they fabricate anchor bolts with J end of any length using A325. I asked them if they have other material for high strength bolts.. they said they only have A325 and 4140 but the 4140 is rarely used.. anyone knows if 4140 is good for anchor bolts for my future reference?

This is one of the suppliers I called http://www.weiku.com/products-image/14671581/A325-...

By the way.. why can't you use the A325 as anchor bolt officially? In the Philippines. We don't have any so called f1554 gr 36 or Gr 55..

How do you recognize an f1554 vs an A325 by physical appearance.. can you recognize which by just looking?

Btw.. they okayed after checking the computations the bigger metal plates with additional bolts my contractor did.. and the poor A307 may be sufficient for my application and they specify high strength A325 in steel columns in low to high-rise buildings.

RE: A307 vs A325 bolt

(OP)
Edit.. the supplier said their a325 is made from 1045 steel... so maybe it should be called 1045 steel.. not a325 (which is only reserve for bolts with head?) that can cause confusion.. googling 1045 steel:

http://www.azom.com/article.aspx?ArticleID=6130

So is the f1554 gr 55 made from 1045 steel?

(is a325 made from 1045 steel or from a325 steel or what steel?)

RE: A307 vs A325 bolt

2
The page you posted is a bolt specification, not specifically for anchor bolts, or holding down bolts as we call them in Australia. A325, or its close metric equivalent Grade 8.8, can be used for anchor bolts, but this is a high strength steel. Rarely is a high strength steel needed for anchor bolts, as the mode of failure is almost invariably the concrete, not the steel. Therefore, A307 or Grade 4.6 anchor bolts are very common and should be used when strong enough, because they are more ductile. J-bolts fabricated in A325 may be available where you are, but I wouldn't trust them because A325 is too brittle to be bent in that way.

RE: A307 vs A325 bolt

Also J bolts are not the best application anymore.

Just make sure you dont go in this building when finished, especially during an earthquake.

RE: A307 vs A325 bolt

(OP)
Thanks Hokie and others. It finally all made sense.. when bolt is mentioned earlier.. I thought anchor bolts is being meant. But like the word "men" to stand for humankind.. adding a "wo" to "men" become "women".. the meaning changes.. so bolts is general terms and anchor bolt is part of the genetic bolts like women are part of men (meaning human).



I bought the different bolts to try to distinguish them (see picture above). I don't have any a325 anchor bolt.

The store says the left one is the A307.. is there any steel even weaker than the A307? because there is lurking fear it may be weaker.

I also understand from Hokie:

1. Why structural engineers didn't emphasize to use grade of steel in anchors because concrete failure occurs first before the yield strength is reached.

2. Two years ago when the engineer told me to add anchors and didn't specify grade. I asked the store what was available. They mentioned A307 and a325. And I asked here at eng-tips which was better. Someone answered A307. So I got the A307 two years ago and days ago when I visited the store and the owner said they had both A307 and high strength a325.. I seemed to regret why I didn't get the a325.. i forgot why I got the a307 and tried to find the thread but couldn't.. this was why I posted days ago to request enlightenment. Now I'm enlightened.. and feel better for not making mistake in buying a307 two years ago.

RE: A307 vs A325 bolt

Quote (Now I'm enlightened.. and feel better for not making mistake in buying a307 two years ago. )


You mean A325

RE: A307 vs A325 bolt

hokie, you wouldn't be able to get a J-bolt in A325, because the A325 spec is specifically for hex headed bolts. If it's rod or anything other than a hex headed bolt it isn't A325.

If it's something other than a hex head bolt with the same material specs, it's A449. It apparently has lower quality control requirements than A325, though.

http://www.portlandbolt.com/technical/specificatio...

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