ACI318 chapter 21

[newdnbea]

i have a question about lap splice under seismic load. ACI318-05 21.5.4 addresses development length of bars in tension. i think it only applys to the joint of SMF. when we calc the splices in beams, columns, foundations, we still use the equations in chapter 12. 21.7 does say the splice in wall shall follow chapter 12. am i right? thanks

 

[x5bulldog]

Remember there are only certain places in flexural members(beams) and members subjected to bending and axial (beam-columns) where lap splices are allowed.

Read section 21.4.4.5 where you also need to use ACI equation 21-6.

Also,if you're curtailing your longitudinal reinforcement in your beam check ACI R21.5.4. Compare it with ACI chapter 12 and see which controls. (development lenghts)


For walls don't forget about ACI 21.7.2(c). Usually at and near boundary elements.

Anything I am missing? Anyone?

 

[x5bulldog]

Correction

For walls

21.7.2.3(c)

 

[newdnbea]

let's be specific. 21.7.6.4e says "horizontal reinforcement in the wall web shall be anchored to develop fy within the cinfined core of the boundary element." the ld here should follow chapter 12 or 21.5.4?

you can find some similar clause all over chapter 21.

 

[x5bulldog]

"ld" from chapter 12.


One quick note. I have seen a publication that uses "ld" from chapter 12 with 1.25fy. This publication is the PCA Notes on ACI 318-05.

I would use 1.25fy to be safe.