Post installed anchor/plate drilling 6

[Pixy]

Who among you have tried drilling concrete pedestal with already base plate on top. That is. You will drill through the baseplate and concrete and even cut through any rebar inside (that is redundant anyway just believe me).

What is the cheapest rotary hammer wattage you could get for this? Let's assume there still space above to position the drill tool. That is why I need just compact and cheap one. The base plate has thickness of about 0.6". The rebars have either 0.78" or 0.39". Don't suggest extremely expensive gigantic drilling for oil exploration. It's just for rare one time use. I couldn't hire any tool.

Also the above anchors can be inserted into the baseplate, concrete base, right? or is there no anchor bolt that can be used with baseplate already in place?

 

[Enable]

phamEng, are you eng-tips owner? It seems you have the power to shut down threads. That's what you did a year ago and about to do it now. And people seems to fear you. Do you have military background? Are you Russian? Can you please spare just one building for now?

phamENG is one of the most thoughtful and considerate posters on this forum. I do not know him personally but I have no doubt that he is an excellent engineer. We are lucky he continues to contribute here for all of our benefit.

Likening him to entities engaged in war is absolutely dumbfounding. Also, please keep politics out of this part of the forum.

To be frank, you and your mentors seem woefully underqualified to be doing what you are doing. I've read your threads and have nearly 0 clue what is going on even 50 replies in. The fact you keep getting intelligent replies trying to figure out your problem says a lot about the nature of the people who contribute here.

 

[phamENG]

eng-tips owner? Nope, just a guy who wastes entirely too much time here, though most of it benefits me one way or another as I do love learning, and I like to think others benefit from my time here (thanks, Enable!)

power to shut down threads? Nope. I've flagged a few threads for advertising, but I can't shut them down myself.

Do I have a military background? I do. Though operating circuit breakers and adjusting voltage and frequency outputs on a turbine generator are hardly skills that strike fear in the hearts of my adversaries.

Am I Russian? Nope. Though I do have some Norse blood in me, so there might be a few thousand 30th cousins 59 times removed over there through the Kievan Rus lines...so I suppose that counts as guilty by association? (Though I'm probably more likely to be related to as many Ukrainians, so there's that)

Removing the top two stories to give yourself an added buffer in seismic to account for construction defects? Yikes. I give our contractors a hard time, but that's a complete lack of faith. That's outside of my realm of experience, so I can't really comment substantively on it. Though by the looks of that parapet wall, I get it.

If the parapet wall was designed to go that high and reinforced per that design, but it was stopped short, then I wouldn't be too worried. Don't try to lap - you don't have enough. You'll either have to use mechanical splices or weld the rebar. Welding will require chemical analysis to ensure weldability. If those two options wont' fly, it's probably best to tear down the couple courses of block and start the wall over.

By stick welding are you referring to SMAW (Submerged Metal Arc Welding)? The short answer is yes it's possible. The long answer is that it's going to depend on what weld procedure is used.

 

[Pixy]

Submerged? SMAW stands for Shielded Metal Arc Welding. This is the only one we have.

Our workers/masons thought that purpose of lapping rebar is to tie the 2 laps with wires. And the strength is in the wires. They don't know that it is in transfering the concrete bearing from rebar to another rebar. So their suggestions to only chip small vertical portions to tie the lap wires won't work because the new mortar put can just crack. So your suggestion it can't work confirmed the suspicion.

My mentor said to weld the rebars. But our rebars are grade 60 (60 ksi) or 414 Mpa. Isn't it this is more fragile to be welded? I heard only grade 40 (40 ksi or 275 Mpa) can be safety welded? But we don't have any welding code here and only poor people do welding so not reliable.

So it's down to using mechanical splice or demolishing the existing walls and putting new wall.

1. If epoxied dowels will be inserted. Will 4" drilled depth be sufficient for the 3 meter (9.8 feet) high wall. Plan to space the drilled rebars every 8 inches.

2. If concrete wall would be put. This can make it act like shear wall. But out of plane lateral load will still have half of height taken by the top beam, isn't it? This is because shear wall can create boundary condition that can overstress the column. But this is only in the parallel plane, not out of plane (perpendicular) lateral load, right?

3. I also found the old beam photo and dimensions. It is 30mmm (11.8") width and 500mm (19.68") depth beam with 20mm (0.787") longitudinal rebars, the masonry blocks (or CHB (Concrete Hollow Blocks) is 6 inches thick plus finishing at both sides for total thickness of about 7" or 7.5". Do you put your wall at edge eccentric to the beam or at center of beam? no problem putting it at sides? I asked this a year ago and no one can compute it here. 99% put it at edge but thinking of torsion (but then slab can brace the beam against torsion even if wall is put at edge, isn't it? Or can the beam crack at the wall boundary at middle?

That's all I need to know for now (this weekend). Thanks guys!

 

[phamENG]

Yep. Got my wires crossed. It's shielded metal arc welding (SMAW) and submerged arc welding (SAW) - stick welding being a vernacular expression for SMAW.

Some 60ksi bars can be welded, but not all. In the states we have ASTM 706 for low-allow steel reinforcement. It's 60ksi yield and can be welded. It's commonly used in high seismic areas, but not where I practice. It's all about the metallurgy. But if you have much doubt, then avoid it.

Depth of the holes depends on the material used (each product is different and has different strengths) and it will depend on the loading. You really need to get a handle on that before you do anything else. Until you do that, your 1 and 2 aren't really answerable beyond some vague thoughts. Our standard practices won't help since they aren't standard practices where you are.

If you put the wall on the edge with an eccentricity relative to the beam, you'll have torsion. Easy to design for. ACI has a whole section on it. Not sure what edition you have - they moved everything around so I don't know where you'll find it in your book. Look up torsion in the index and you'll find what you need.

Something to think on: My litmus test for anything I do - would I feel comfortable with my 2 year old son being in this building during a design level event? If I can't say yes with confidence, then I have no place engineering the building and I should step aside for someone with sufficient qualifications. Put yourself in that position - what's your answer to that question?

 

[Pixy]

12mm (0.47") rebar 40 ksi yield will be epoxied 4 inches deep in the beam and o.c. every 150mm (6") or 200mm (8") apart. 6" hollow blocks will be used for final wall thickness of 7 to 7.5" and 3 meters (9.8 feet) wall height. This is closest possible reinforcement for masonry wall already.

Do you have pictures how they epoxied wall dowels to the bottom beam in your place? Or haven't you seen any? I just want to have ideas how others do it. That's all. Or no one do it there? Meaning no epoxied wall bottom dowels at all done there? Please share what you actually tried before, the bottom planted epoxied dowels.

There are so many references about post installed chemical or epoxy anchors in baseplates in concrete pedestral, but nothing on bottom beam of a masonry wall? Why?

 

[Pixy]

Btw.. PhamEng, for over a year I've pondered your following words:

"If the cement board and frame are doing nothing structurally, then your best bet is likely to remove them, drill and epoxy rebar into concrete beam, and build a concrete masonry wall that bypasses the W8 and goes to your required height. Weld an angle with the leg facing down on the bottom flange of the beam with long slotted vertical holes and attach that to the masonry - add a low friction washer if they're available.".

So my last question Please clarify what you meant. In our constructions in the country.. for walls that don't coincide with I-beam or go above it at the side. What workers do is to create a concrete bond beam in the masonry and then weld the rebars direct to the flange at the side enclosing the bars with concrete. But many structural engineers just want the wall directly under the I-beam and welding to bottom because they don't know the details how to connect at sides of I-beam. So will discuss with them the following technique.

I understood what you meant by "Weld an angle with the leg facing down on the bottom flange of the beam" but I can't understand the next words "with long slotted vertical holes and attach that to the masonry". Did you mean welding another vertical bar to the angle bar beneath the flange then putting holes in the bar and inserting rebars to it?? (like in above illustration?) Or did you mean putting holes in the angle bar itself? but why did you mention "long slotted vertical holes"? How do you connect this to the angle bar?

I literally have been thinking of it for a year and discussed with dozens of structural engineers. They could never visualize what you were describing in the most perflexing sentence I've encountered in my life. So please clarify. Many thanks!

 

[Pixy]

Dear PhamENG,

Our Welding Code is ACI as specifically mentioned in the specifications in the structural plans above. We just copy anything ACI have in all our general notes.

However there is one problem. We mostly use ASTM A615 as ASTM A706 weldable bar is more expensive and no contractors would buy them unless there are exclusive welding. This is the chemical difference between A615 and A706.

The following is actual chemical compositions of our wall bar.

It's confirmed to be A615 as carbon is more and A615 are ordered by the contractor as confirmed. Percentage of carbon is at the ATSM A615 standard. So it's not exactly weldable.

However in the structural plans (below) when the masonry wall was submitted for extension. All the A615 bars are to be full welded. So we didn't proceed with it because A615 bars can't be full welded because of possibility of fracture. And we can't preheat the bars for lack of equipment.

Well. In fact, in 99.99% of structural plans in the country. They all assume A615 can be weldable. In fact. 99.99% of constructions that use steel beam on top has the A615 rebars of the wall welded beneath the steel beam.

PhamEng. If your angle bar under flange with "long slotted vertical holes" can be used without welding the A615 rebars. Then it is much better. Of course we will submit the structural plan with that details. We won't just build it. Don't worry about this.

Therefore can you at least show in the illustration given in last message. How your "long slotted vertical holes" work? Is your technique copyrighted or trademark? If you don't want to show it. Why did you describe it or mention it a year ago, and got me thinking of it for a year without any clarifications from you. Come on. Save the country. All of our Ibeam on top have wall with non weldable A615 bars welded to bottom. In the event of seismic shaking. Bar can further fracture and the wall can fall down. Therefore your details can save many. What if your distant relative come here. I'm willing to pay you by you just showing the illustration how the "long slotted vertical holes" work? Did you mean insert bolts to it with baseplates at the beam bond of the masonary wall??

 

[Pixy]

Today I think I have cracked the secret of PhamENG wall.
But first. Some background.

1. In our country, we copied the US ACI code word for word (except changing the units to metric). That's why our codes are always a few years behind current ACI because our editors have to change the units.

2. We almost never use cross frames, shear walls or even use the core of stairs as part of lateral resisting system. All are moment resisting frames in the column and beams. Except if a building has elevator, you have no choice but to put the core for the lift.

3. In our walls (shown above). The above details are built in 99.999% of buildings and homes. That is. There is horizontal and vertical stiffener every 3 meters (9.8 feet) (you use bond beams blocks elsewhere). And the top rebars single or stiffiner are always epoxied to the bottom of the beam above the wall. Our hollow blocks are always filled, no hollow part. So I think this makes it some kind of semi shear wall, where it generally can't slip, and the beam deflection can resist the wall and distort up. Same with column? What other countries build like this? Are we the only crappy country with this?

4. With this setup, can you still say half of the height out of plane lateral load is taken by the above floor diagraphm and half below. Or not valid since only full fledge shear wall counts in half up and down contribution? This is direclty connected to this thread because of how the shear in the masonry wall gets to the RC column so needed more strength in the baseplate requiring anchor retrofit.

5. Lastly, I think the following is the secret of PhamENG wall. I spent many hours searching at google for how a wall top reinforcement should look like. And i found this.

So he expects the beam to deflect and not distorting the wall. So called slip connection. None of us has done anything like it. Even though we use ACI codes, we never read many parts, and just use habits in our practice. So if I'll submit the plans and do it. I may be one or very few who have done it.

It can still cause half of the wall height to have lateral reaction to beam or diaphragm above?

 

[dauwerda]

Pixy,
To be clear, A615 rebar can be welded. Per your pictures above, the welding code to be used is AWS D1.4 (the same as the US). As noted, due to the higher carbon content (or carbon equivalency), A615 will typically need to be preheated before welding operations are performed to prevent embrittlement. D1.4 provides a table for the preheat requirement based on the size of the bar and the carbon content of the actual steel (requires having heat reports, which it looks like you do). Even if you don't have the heats giving you the chemical makeup, D1.4 still provides a preheat temp, it is just higher than might otherwise be required.

As to not having the equipment to preheat - it doesn't take much, just a propane torch will do it.