RC Large column section, Tie configuration which of these is better? 4

[ST04]

Dear colleagues,

For reinforced concrete column having bi-axial bending moment (both axes) with large cross section, do you have any suggestion for the ties/links configuration?

In BS 8110,3.12.7.2 "Every corner, bar, and each alternate bar (or pair or bundle) in an outer layer of reinforcement should be
supported by a link passing round the bar and having an included angle of not more than 135°. No bar
within a compression zone should be further than 150 mm from a restrained bar."

Lets see these two draft sketches, they only represent a case similar to what I'm dealing with.

http://files.engineering.com/getfile.aspx?folder=7afaa634-bea9-4076-9a7f-9628fb5e4ae7&file=c.gif

I thought of adding two hooks for the longer side of the section but I'm not sure if it is allowed.

http://files.engineering.com/getfile.aspx?folder=76c3f3ec-ef73-41b4-97e4-3b1cac47ac78&file=c2.gif

Any suggestions?
Regards

 

[ST04]

Blue colored link goes along the whole perimeter

 

[BAretired]

Unacceptable...the bars must be tied as on the first sketch to prevent them from buckling outward.

BA

 

[BAretired]

Some of the bars on the first sketch are not adequately tied either. Probably the best solution is to reduce the number of vertical bars and increase their diameter. This will reduce the number of ties required which will make pouring the column easier.

BA

 

[rapt]

BAretired,

Agreed, the secone is useless while the first option is close but there are bars in both directions that should be tied but are not. The wording of the code clause is very clear. A tie beside a bar but not "enclosing it" makes it an untied bar. Every second bar must be enclosed by a tie and any bars > 150mm apart must be enclosed. Enclosed means it has to be in the corner of a tie, not beside one!

 

[JAE]

Yes - I agree with BA too. Neither work according to code.

 

[csd72]

A bar only has restraint if it is either at a 90 degree corner of a rectangular tie or if it has a 180 degree hook around it.

You need to have this condition at every second bar on each face.

Looks like you need to do some reading on this

try:

http://www.concretecentre.com/onlin...ry/publication_details.aspx?PublicationId=752

I would also recommend you get your hands on the concrete detailing manual.

 

[ST04]

Thanks everybody
I appreciate your inputs.
Best regards