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
Professional and Structural Engineer (ME, NH)
American Concrete Industries
www.americanconcrete.com
RE: A307 vs A325 bolt
RE: A307 vs A325 bolt
RE: A307 vs A325 bolt
RE: A307 vs A325 bolt
Probably alot cheaper then A325
RE: A307 vs A325 bolt
RE: A307 vs A325 bolt
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
RE: A307 vs A325 bolt
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
The A307 bolts may be OK. You need an engineer to verify the demand does not exceed the capacity.
RE: A307 vs A325 bolt
RE: A307 vs A325 bolt
RE: A307 vs A325 bolt
RE: A307 vs A325 bolt
RE: A307 vs A325 bolt
RE: A307 vs A325 bolt
See http://www.portlandbolt.com/technical/faqs/substit... and http://www.portlandbolt.com/technical/faqs/can-the...
RE: A307 vs A325 bolt
RE: A307 vs A325 bolt
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
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
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
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
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
RE: A307 vs A325 bolt
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
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
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
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
RE: A307 vs A325 bolt
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
RE: A307 vs A325 bolt
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
Where is this structure being built?
RE: A307 vs A325 bolt
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
RE: A307 vs A325 bolt
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
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
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
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
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
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
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
RE: A307 vs A325 bolt
(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
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
RE: A307 vs A325 bolt
Just make sure you dont go in this building when finished, especially during an earthquake.
RE: A307 vs A325 bolt
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
RE: A307 vs A325 bolt
You mean A325
RE: A307 vs A325 bolt
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...