Reinforcement Substitution

[nicholi]

What is the opinion of substution of reinforcement bars for a reinforced concrete beam. The drawings call for 2 - 25M and 3 - 25M bottom bars, and the contractor wants to substitute one 25M bar (500mm2)with 3 - 15M bars(600mm2). There are the obvious issues of sufficient clearance for concrete to get through, etc, but is this an okay practice to substitute bars in a pinch?

 

[SperlingPE]

No.
There are other factors to consider before allowing substituting reinforcing bars.
Z crack factor
lap distances
bar clearances between bars
continuity
Substituting of bars should be reviewed by the designer.

 

[UcfSE]

It looks like you are replacing 3 bars with 9 bars in the bottom, and replacing two bars at the top. Correct? Replacing that many bars could cause your depth to the center of your reinforcement "d" to decrease compared to what it is with only 3 bars, depending on the width f the beam.

If you are the engineer who will be reviewing this, it's up to you. As Sperling mentions, there are other things to consider besides simply providing an equal amount of steel area or more.

 

[Maury]

This should be referred to the Designer, the Engineer of Record, since that's the person who has signed and sealed the plans and has the ultimate responsibility. The shop drawing reviewer or the job site inspector should be trying to ensure that the work is in conformance with the plans, not trying to redesign it on the fly. You need to learn to recognize a minor change from a significant one, and this isn't minor. If the Contractor is in a pinch because he doesn't have the proper steel, let it pinch until he does the job right.