RC Walls reinforcement ties 2

[MK1000]

Hi,
I am designing an RC wall with reinforcement layer near each face, do I need to provide crossties through the thickness of the wall?

I have read the ACI318-11 14.3.6 limit for 1% of the vertical reinforcement, is there a similar limit in AASHTO or other overseas codes like the ?

Thanks.

 

[hokie66]

Ties in walls are rare, and they are required only in highly stressed areas. You would need to provide more information in order to get a sensible answer.

 

[asixth]

Only for high compression loads. The concrete code which I use requires it when the stress is greater than 0.6*0.85*fc. I have only seen engineers provide these ties when the compressive stress under permanent loads exceeds this limit. The 0.6 is a strength reduction factor which varies code to code.

 

[DST148]

@MK1000 - Ref. ACI 318-05. Lateral reinforcing requirements for reinforcing (verticals in columns / pedestals and longitudinal in beams) are applicable only if the reinforcing is used as compression reinforcement. Not every vertical member subjected to axial + bending is a compression member for detailing purposes.
If the subject wall can be designed using the empirical method of Chapter 14, you don't need cross ties for vertical reinforcing.
Moreover, the axial strength equation (14-1) is based on concrete strength, cross-section, and slenderness of the wall; reinforcing does not figure in.
You may also compare eqn. (14-1) with eqn. (22-14) given in structural plain concrete section of the code.

 

[MK1000]

@asixth - which code do you use?

If I have to provide ties, are these ties similar to column ties or maybe less stringent? In my case it would be unpractical to specify column ties !

Thanks guys.