Base Plate on sides
Base Plate on sides
(OP)

Let's say you have a weak A307 bolts installed on top of concrete. You want to strengthen the base plate yet you don't want to add more bolts on top. What would happen if you add base plates on the sides? Does anyone do this? Can it cause
a) Increase in tensile strength of the part in tension?
b) even increase the strength of the compression side
c) pryout failure of the two adjoining plates?
d) breakout failure
e) can you develop the side base plates as tension block?
If no one does it. What is the failure mode of it?






RE: Base Plate on sides
So, you see on the sketch where the concrete could be in tension?
Now, on the sides of the same concrete pad, if there were sideplates attached, show the extra anchor bolts inserted into the concrete from each of the sides, or from two opposite sides.
Can you see where those added "pullout cones" are going to overlap the already-stressed tension cones from the vertical anchor bolts?
If you can arrange the side plates so there is no extra tension in the upper part of the concrete pad, your idea may work. Otherwise, you're weakening the upper part of the concrete with more drilled holes, then adding more tension to the same volume of concrete with the new bolts.
RE: Base Plate on sides
In base plate design illustrations, the concrete underneath are shown empty. What if there is many reinforcement below base plate.
See pic of the actual concrete base before pour. The anchor bolt used is the weak A307. The longitudinal bars are grade 60. In pullout cones.. does it also occur irregardless of what kind of reinforcement you have inside the concrete? Supposed the load can survive the A307 yield strength.. would the reinforcement help in suppressing pullout cones?
RE: Base Plate on sides
BA
RE: Base Plate on sides
or
http://imagizer.imageshack.us/v2/800x600q90/908/qn...
RE: Base Plate on sides
RE: Base Plate on sides
The rebar definitely helps. If you're using ACI appendix D, you'll get a modest boost for having some rebar crossing the failure cones. If you're designing the connection using a strut and tie based algorithm, like Widiato's method, then you might be able to squeeze considerably more capacity from the system but the detailing of reinforcement, particularly it's development on either side of assumed failure cones, will become very important.
If you post a sketch of your anchor bolt layout and your loads, we'll likely be able to offer a good deal more help.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Base Plate on sides
This is the actual real anchor layout
(or see http://www.pbase.com/image/161555922 if no image above).
The anchor is the A307 16mm with depth about 1 foot J shape that is distance about 2.8" to 3" inches to edge. What rule do you use for anchor near the edge.. ACI said it must not be less than 1.5 Hef where Hef is the height of the anchor. The anchor is 1 foot size.. so if the rule is to be followed.. it must be 1.5 feet (18 inches) from edge, the actual is about 3 inches to edge. Even if the depth of the anchor is just 4 inches.. the 1.5 Hef would make it 6 inches away from edge.. so pryout is a danger huh? But with reinforcement below it.. I wonder how it functions with pryout.
The load would be center support for gable rafter beams (side w8x21 5.5 meters) connecting at middle. The sides also use the same anchor layout. See below:
X------W------X
The W is the middle supporting the 2 rafters from sides. The 2 rafters are connected at middle and carried by the baseplate. IN extreme seismic shaking where the wide flange can flex and even bend in the weak axis. The connections must be strong.. so is your estimate, would the present anchor bolts be sufficient?
This is why I plan to use the very expensive Hilti chemical anchors to put it about 100 mm away from edge to reinforcement the poor A307.
RE: Base Plate on sides
What I'd really need to see is a dimensioned sketch showing the bolts, base plate geometry, and column cross section. Additionally, a sketch showing the loads on the connection would be very helpful.
Given that the framing that you're supporting here is pretty light, I'd be very surprised if the connection couldn't be made to work with the A307 bolts. A307 bolts are generally inferior to A325 bolts but will certainly have some reliable capacity that you can utilize. The bigger issue may well be the use of hooked anchor bolt ends. Again, there is some capacity, but it's not usually the best way to go where anchor bolts are expected to resist tension.
I would proceed as follows:
1) Evaluate what you've got using ACI 318 Appendix D or your country's equivalent standard. It may be fine fine as is.
2) If #1 doesn't work, look into a more sophisticated evaluation procedure like Widianto's: Link.
3) If neither #1 nor #2 work, revisit the concept of adding supplemental fasteners.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Base Plate on sides
If Hilti anchors are to be installed at a closer spacing, they would also be contained within the column reinforcement cage. Four anchors should be sufficient, sized to resist seismic loads.
BA
RE: Base Plate on sides
the hilti chemical bolts will be 16mm and 4 inches in length. the 20mm would be too big and we dont have concrete drilling machine more than 4 inches.
RE: Base Plate on sides
This is the 0.5x0.5 mtr base plate for the column top shown earlier:
The blue dot is the A307 bolts (1 foot embediment) located about 3" from edge corner. The red dots are the additional expansion bolts. Unfortunately. There is no stocks of the Hilti chemical bolts so have to use local GI expansion bolts (5" embediment is the longest I can find), I wonder what is the yield strength of GI expansion bolts? The light blue wide flange is the 1 foot support of the rafter.
The contractor made the base plate 0.5x0.5 mtr instead of the smaller one in the plan because he can't find any anchor bolts that is 7 inch deep. The designer said the corners can be used if the base plate is thick. We have 16mm base plate. But learning the A307 is not A325. I told the contractor to add the additional bolts the designer has designated.
This is the column actual sections (all the columns have similar reinforcements)
This will carry the rafters shown below (using w8x21 5.5 foot rafter and 2x6" 1.8 mm purlins spaced at 0.6 mtr with light roofing material).
I'm concerned about seismic loading.. kootk said the rafters will flex back and forth... I read in ACI that the metal plates can have moments and compression, tension side too. So I wonder if the A307 can make it with additional bolts at middle. The designer has already left the company and last thing he said was to make the plate thicker if we want to use the corner A307 or put additional anchors at mid part. I wonder if metal plates have interaction diagram too where there is particular failure moment and failure axial load. ?
RE: Base Plate on sides
Holes in base plates should be drilled in the shop in accordance with approved shop drawings prior to shipping to the site. If steel is to be primed, primer should be applied in the shop before shipping.
BA
RE: Base Plate on sides
(the holes were done by the steel were epoxied primered)
You said you haven't seen steel being primered on site. Here's the picture of it being primered on site.
Note very important that in my country.. 100% of contractors do it that way because they ordered from the steel supplier the raw pure naked steel then contractor primered it at site.. no one did it at shop (because they have no shop just to waterproof them before delivery.. this is true in all major contractors and builders).
By the way. I followed all your instructions. I let the structural firm verified the computations of the contractor overdesigned larger plates and more anchor bolts and it is ok. The wife of the structrual engineer head was jus pissed with me year ago when I visited their company dozen times for the epoxy void and carbon fiber wraps asking questions and discussions computations they could have overlooked. So if I'm learning how to compute manually.. it is just to verify their design.. not to design on my own.. I'll always have them updated of an changes.
RE: Base Plate on sides
The wife's attitude may explain a few things.
RE: Base Plate on sides
http://www.boysen.com.ph/products.do?item_id=951
The wife only wants to deal with big project because they design 40-storeys. So she looked down on my 2 to 3 storey. But the company has made some mistakes like suggesting pure epoxy on column 2 inches voids (from honeycomb) and forgot some stirrups and I had to pay for the carbon fiber retrofit design. So the only way to have peace of mind is to learn how to compute manually and become a structural engineer so can verify the project. In our country. most structural engineers are civil engineers. We don't have a course in structural engineering.. so I may one day join them to verify their design and perhaps write an article about danger of epoxy repair in column void to strengthen my position over the contractor and designer.
RE: Base Plate on sides
RE: Base Plate on sides
No they are putting epoxy primer under the sun and even while a bit of rain.. so new rusts form in parts of steel missed. In our country. This is the normal thing contractors do with laborers only earning $10 for working 10 hours a day. Such poor practice I know.