Rebar Splicing in columns in special moment frames 1

[Penpendrum]

Hello everyone. . .

can anybody please clear me out the purpose of only splicing half of the reinforcement in one section and the other half in other sections for columns.. i have been told that this would somehow prevent congestion.. but is it stated in the ACI 318-11 commentary and in what section? I have been discussed in my previous thread that class B splices does not need to be staggered.. but why is it the inspector in the site won't allow me to splice all bars in one location. . the column dimension is 610x610 mm with 12-25mm DRB , 435x435 mm with 12-25 mm DRB , 585x585 mm with 12-25 mm DRB. .

the inspector showed me book (Design of Reinforced concrete by Jack C. McCormac * James K. Nelson) on Page 209 states that "Splices should be located away from points of maximum tensile stress, Furthermore, not all of the bars should be spliced at the same location- that is, splices should be staggered". .

the book was also based on ACI and it got me in a confusion that the statement above is in conflict the class B splice defined in the ACI code. .

please help me out . . I could loss a lot of money if He would demand to redo the work. ...thanks.

 

[TehMightyEngineer]

I just went through writing up a lecture for a review course regarding special moment frames. The only item regarding location of lap splices for special moment frames in ACI 318-11 is section 21.6.3.3 which requires lap splices occur only in the middle half of the member length. Lap splices are not permitted in joints, within 2h of the joint, or at locations where analysis indicated flexural yielding caused by inelastic lateral displacements of the frame will occur. Lap splices need to be designed as tension lap splices and must be confined with the special seismic hoops of section 21.6.4.2 and 21.6.4.3.

I find no requirements that you have class A lap special frame column splices. In fact, PCA Notes on 318-11 Example 29.3 shows a special moment frame column and specifically states you have the option of using either class A or B splice and chooses a class B splice for the example.

For intermediate and ordinary moment frames there are no restrictions on location of lap splices.

Professional and Structural Engineer (ME, NH, MA)
American Concrete Industries

http://www.americanconcrete.com

 

[TehMightyEngineer]

To reiterate from the previous thread, it's recommended that you stagger splices but I know of no requirements that prohibit you from lap splicing the full reinforcement assuming all the class B lap splice requirements are met. Yes, congestion may be a concern but this is a separate issue and unless it is actually too congested to build then it shouldn't be something they reject.

Professional and Structural Engineer (ME, NH, MA)
American Concrete Industries

http://www.americanconcrete.com

 

[Penpendrum]

thankyou TehMightyEngineer .. you have clarified it to me.. I just want to ask further if this also applies to special moment frames for beams that we are only allowed to splice within center half of distance 2D from support? cuz I thought that top bars are only allowed at the middle third of the beam ? so does this mean that I could lap splice the top bars not from the middle third of the beam but away from 2d from support in special moment.? And Am I allowed to lap splice in all bars in one section for beams? and can you please some site more of this sections to make me feel confident...

thankyou again TehMightyEngineer ... you are a life saver..