AWS D1.4 2

[ChipB]

I've got #8 bars for a retaining wall, but, the dowels used 48" lap splice I called for on the plans are only sticking out of the footing 38" to 40". I can mechanically lap them at $50 a piece, or, I can weld per the above AWS specification. I don't have this code, but, I'm willing to bet it's a full pentration weld that's required. Anybody know? There is 100+ bars that need to be spliced. (Can you say CHA-CHING?)

Not that it's funny, but I went there on Friday prior to the pour, talked with the guy doing the footing, and showed him the plans and told him it was imperative for the 48" length to be from the top of footing to the end of the dowel.

 

[SperlingPE]

48 bar diameter lap splice?
What are the conditions? Do you need to fully develop the bars?
More information, please?

 

[ChipB]

12" Masonry cantilevered Retaining wall, 12' tall. Same wall as

http://www.eng-tips.com/viewthread.cfm?SQID=90740&SPID=507&newpid=507&page=1

I did originally design this as a poured wall, the contractor wanted to change it to masonry. I advised against it, but, since he is paying me (he is the owner of the company I work for), I designed per his preferences.

Yes, they need to fully develop the tension.

 

[whymrg]

According to AWS D1.4 rebar splise may be flare-v-groove weld, when you place rebars side by side. Effective weld size E=0.6*R (R is radius of rebar). You may have weld on one side of rebar or on both sides. 125 percent of "fy" will give you required length of weld.

Also you may use direct butt joint (v-groove or bevel-groove), or weld both bars to plate or angle.

Remember that ASTM A615 Grade 60 bars shall be welded with E9015-X, E9016-X or E-9018X electrodes per AWS D1.4

Good luck.

 

[SperlingPE]

I do not have the masonry requirements for lap splicing steel in front of me. For cip concrete, 40 bar diameters should develop the bar at the splice. Review splice requirements, you may have enough to make your splice.
For concrete see ACI 318, chapter 12.

 

[SlideRuleEra]

Could you increase the compressive strength of the cell fill concrete enough to effectively shorten necessary rebar development length to the 38" / 40" available?

 

[VoyageofDiscovery]

Hi ChipB,

This may be a long shot, but retest your 2000 psi concrete. If it is significantly higher, recalculate to see if it will be adequate. Good thing you have been inspecting!

If it's too late you will probably need to make an external remedial design to transfer the moment. It will be ugly.

Regards

VOD

 

[VoyageofDiscovery]

Hi ChipB,

I believe the recent ACI 318 has eliminated the need for 1.7 x development length for Class C splices and reduced Class C splices to Class B. Your situation should just work out!

Hope this helps.

Any comments on this change is welcome.

Regards

VOD

 

[ChipB]

Thanks VOD & whymrg,
I had them order the mechanical laps yesterday. There is a preheating requirement for A615 steel that made welding substantially not economical!

FYI, yes, I still have a job (for now). I'm sure they aren't happy with me, but, I can find another job. My stamp on the other hand.....

 

[Focht3]

Hang in there, [blue]ChipB[/blue]. Remember that someone's life may have been saved by your steadfastness. Good clients will respect you even when they don't always like the cost implications of every engineering decision.

Besides, you weren't the one who changed the design from a poured in place wall to masonry block...



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora. See faq158-922 for recommendations regarding the question, "How Do You Evaluate Fill Settlement Beneath Structures?"

 

[boo1]

Chip the preheating requirement is if the rod is damp or tepm are less than 50 deg F.

 

[ChipB]

boo1,
If my memory serves me correctly, and, for the most part, it usually does, A615 steel is required to be heated to 300 degrees Farenheit for 20 minutes prior to welding. But, as I said, I don't have access to this spec anymore.

For those interested, this is the mechanical laps they are using:

http://www.barlock.com/products.html

Pretty cool in an engineering type of way.

 

[boo1]

Chip the minimium preheat and interpass temperature of welding reinforceing steel is listed in Table 5.2 of AWS D1.4. For carbon equivalent (C.E.) range (CE=%C+%Mn/6) of up too .45 the min temp is 50 degrees F.

The min temp can go up to 500 F for CE > 0.75 in #11 rod.

Cheers