Rebar lap splices notes

[yakpol]

I am trying to come up with the note about lap splices which combined with the schedule will cover majority of the situations. I greatly appreciate if folks would share well written notes on this subject.

Thank you!

 

[jike]

I prefer to keep it simple and not have all the different class splices, top and other bars, cover, bar spacing, etc. that you find in the code. I take the most common cover, bar spacing, etc. and use that to determine my laps. For concrete, I list two bar lap splices: Vertical bars and horizontal bars. The horizontal bars are all considered top bars. The vertical bars are not. For masonry, I do something similar.

I have found over the years that this covers 99+% of the situations and then you can always say UNO and have something unusual on a detail if need be.

 

[jike]

The contents of the schedule of laps is much more important then the note that refers to the schedule. The note should simply say: Provide the following lap lengths for reinforcing steel in concrete unless otherwise noted. (Followed by the schedule).

I use separate notes to cover:
vertical dowels required at all walls, piers and columns
column and pier ties
non-continuous top slab bars
continuous horizontal wall reinforcement
horizontal dowels at all intersecting walls
corner bars
special reinforing at construction and control joints
additional reinforcing at wall and slab openings
etc., etc.

These notes may vary by engineer and job type, but I hope it gives you some ideas to consider.

 

[yakpol]

jike,

Thank you for the tips. I have not done much of building design, mostly transportation projects and extensive schedules are somewhat new to me.
I am looking for a note which will cover allowed locations of lap splices and staggering splices of ajacent bars.

 

[jike]

Typical locations for splices are:

Joints for vertical construction....
columns, walls, piers: at footings, at floors
Joints for horizontal construction....
walls: approx. 60 feet
beams & slabs: middle 3rd of span

Staggered splices are unusual in building design. Common in circular tank walls.

 

[youngstructural]

Staggered splices are common (and desirable!) in buildings designed for seismic loads... But you really should not be designing in a high seismic area without someone to support and guide you through the first few buildings...

If you are in a seismic area, please do say so and I will try to give you some guidance. Schedules are less commonly used in areas of high seismicity due to the complication of the situations. Also if you are engaging in capacity design I would encourage you to have your finished plans reviewed by a more senior engineer familiar with detailing of splices for a seismic zone.

Cheers,

YS

B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...

 

[yakpol]

Well, It's not a building but a huge pump station. Some elements are designed for high water pressures. Reinforcing rate is very high since crack control governs designs. In many cases bar spacing 6 inches and I do intend to stagger splices.

 

[youngstructural]

As long as you aren't expecting any plastic elongation of the structure my point should be moot for your pumping station...

Cheers,

YS

B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...

 

[graybeach]

One thing your note should not say, "All lap splices and embedments shall be in accordance with ACI 318." I sometimes encounter consultants trying to pull this.

 

[youngstructural]

Why not say that graybeach? I mean, I appreciate that it is the engineer shirking quite a bit of responsibility, however in partnership with a note to the effect of "Make no assumption in your interpretation of this and any other project documentation. Direct all queries and unfamiliar or in detailed situations to the engineer for clarification." I would see it as being potentially appropriate. That is as long as the engineer has genuinely done all they believe necessary in detailing out connections for the contractor, NOT at all appropriate if used to reduce their total amount of detailing.

What's your opinion of my view?

Cheers,

YS

B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...

 

[graybeach]

I believe the development and lap length calculations should be done by a qualified person, familiar with the forces and other requirements. The person needs to evaluate the spacing, cover, whether the bars are epoxy coated, whether they are top bars, whether to stagger the splices, whether lengths can be reduces by As req'd/As provided, etc. I suppose one could require that the contractor hire an engineer to do these calculations and that the EOR reviews and approves like in steel connections. But this makes unecessary complications in my view, and contractors often do not hire good engineers. The mistakes I find in sealed calculations never cease to amaze me. I have learned to explicitely state that the consultants shall fully detail the rebar when I hire them. This works out well for the kinds of heavy civil structures I work with.

 

[youngstructural]

Fair comment graybeach; And I agree with you.... However I don't see how this means its a bad note for the drawings, PRESUMING that such work has already been carried out by a qualified person, and as per my previous post, the note is being used as a catch-all.

Cheers,

YS

B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...

 

[graybeach]

youngstructural -
ACI-318 actually states the following in the introduction: "General references requiring compliance with the code in the project specifications should be avoided since the contractor is rarely in a position to accept responsibility for design details or construction requirements that depend on a detailed knowledge of the design."
As a rule, I try to keep away from "catch-alls" in drawings and specifications. If something is clearly not the contractor's responsibility, saying it is can muddy the water.