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re: CMU bar locations

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Arunkumar,

I believe what you are asking is are you required to have a doweled bar into the footing, which laps with the vertical wall bars, at every vertical bar location? This is of course assuming as you stated a standard wall with pin-pin modeling, so the theoretical moment will be zero at the footing. Of course I have always thought that by hooking the bars into the footing and fully lapping the vertical bars, you are creating at least a partially fixed connection at the footing (that is neither here nor there).

 

This is of course the standard detail that I assume we all use on our drawings, but this does come up from time to time in renovation/code upgrade jobs, as well as construction errors in dowel placements. This is covered by ACI 530 2.1.10.4.1.3 as well as 2.1.10.4.2 (geesh what is this the Dewey decimal system??).

 

“When a wall or other flexural member is part of a primary lateral resisting system, at least 25% of the positive moment reinf. Shall extend into the support and be anchored to develop a stress equal to the Fs in tension.”

 

I have always interpreted that to mean every 4th bar MUST be fully developed into the footing.

 

2.1.10.7.1.2- allows bars that are lap spliced to be spaced up to 8” or 1/5 of the required lap (max).

 

2.1.10.7.1.2 commentary (CC-38) allows for bars to be lapped in ADJACENT cells, if certain requirements are met. I personally have never done this but under the right circumstances ACI allows it… May be useful in a renovation/retrofit situation.

 

HTH,

Andrew Kester, PE

ADK Structural Engineering

Orlando, FL

 

 

 

I just done a ICF wall design with the boundary conditions at floor level

and foundations as pinned. Because of Simply supported action the rebar

calculated at mid point. Calculated rebar is given in full wall height

without curtailment. While calculating dowel bars as per ACI Min requirement

and by Shear friction. It is Less than Minimum requirement. Is it Dowel bar

locations should match with Main rebar location everywhere.   Can anyone

suggest me in this context.

 

 

 

Regards

 

 

 

ARUNKUMAR  C