Anchor reinforcement development length for anchor bolt within pedestal under seismic design type D 1

[TTTKAO]

Hello All,

I am design a project under seismic design type D and need anchor reinforcement to develop anchor bolt tension within pedestal. i plan to use #25mm vertical bar(the development length is 1412mm as per ACI 318-11 section 12.2.2) and as per ACI318-11 section 12.2.5, the excess reinforcement deduction for development length can't used.

so my understanding is i have to keep such long development length or put hook at top of pedestal.

I am wondering is there any other option for me ?

Thank you!

 

[HTURKAK]

- You may use 90-degree or 180-degree hooked bars to reduce the anchor embedment but consider constructability issues,
- Choose smaller dia . reinf.

or consider to provide more info . to get more specific , better responds.

The following is excerpt from ' Anchorage Design for Petrochemical Facilities '

Tim was so learned that he could name a
horse in nine languages: so ignorant that he bought a cow to ride on.
(BENJAMIN FRANKLIN )

 

[TTTKAO]

Hi HTURKAK,

Sorry I have a few questions for the suggestions, wondering you could help to explain more.

"You may use 90-degree or 180-degree hooked bars to reduce the anchor embedment but consider constructability issues,
- Choose smaller dia . reinf."
Yes, this is an issue. let's take 16mm dia. vertical bar for example. the bending radius is 100mm, 40mm top cover clearance. and i put first tie bar at 75mm from the top of concrete pedestal. this is mean the first tie bar has to put at the hook bending location(40+100/2=90>70). is this allowed from design view ? i didn't find any item from code require the tie bar have to put on main bar straight part. if i use 25mm vertical, the situation would be worse.

"or consider to provide more info . to get more specific , better responds."
how to use this one? could you help explain more.

The following is excerpt from ' Anchorage Design for Petrochemical Facilities '
Do you mean for petrochemical facilities, we have to use straight development length, right ?

Thank you again for your time

 

[HTURKAK]

- ld (which is development length of reinforcing bar will be small for small dia tension reinf. ) You have another option , You may extent embedment length of anchor rod ( hef ) to keep straight reinf. hef = ld + C + (X + db/2)/1.5 .


Provide more details ( e.g. a sketch showing pedestal, ftg. sizes, design loads etc ) to get more specific responds..


- Straight or hooked tension reinf. could be used . Other options , you may use additional hairpin tension reinf.






Tim was so learned that he could name a
horse in nine languages: so ignorant that he bought a cow to ride on.
(BENJAMIN FRANKLIN )

 

[TTTKAO]

Hi HTURKAK,

Thank you so much for your reply, i will let you know once i figure up more details of the pedestal.

i have a basic question regarding to tie bar location , and hope could get some advice from you.

For the tie bat location along the main rebar, my understanding is tie bar can be put at the bend location of the main bar. from Figure R12.5.3(a)/(b) in ACI318-11, seems the tie bar has to put at the bending location in order to meet < 2db requirement. do you agree with my under standing? is there any special attenssion for this situation?

Sorry i didn't figure out how to past pic directly, i drop the pic in the attachment.

Thank you again for your time.

Regards!

 

[HTURKAK]

Eng. ArcherC (Mining),

I do not look to the forum everyday .. The links or stirrups should normally be placed at straight portion for confining the nain bars and conc.

However, if you do need stirrup at uppermost of the main rebars around bend location, you may consider to locate the top stirrup at interior ..( but i will not prefer ..)

Tim was so learned that he could name a
horse in nine languages: so ignorant that he bought a cow to ride on.
(BENJAMIN FRANKLIN )

 

[TTTKAO]

Thank you a lot for the explanation.