Rect Reinforced Concrete Beam with One Main Bar only

[dcnnng]

For a rectagular reinforced concrete beam, what are the reasons that normally we provide 2 main bars? Can we just use only one main bar with the same area and any danger? Thank you!
Regards
Richard

 

[UcfSE]

dcnnng, what code are you using? If you are in the US you should have the ACI 318, or the counterpart if you are in another country. Codes are part of the engineer's tool bag.

 

[dcnnng]

Hi UcfSE,
I use BS 8110 but searching for other codes or reference on the subject matter irrespective of whatever practices or countries. Thank you!

 

[DTGT2002]

How is your structural system designed to operate? In the post by Taro, the terms joist is use to define a load bearing member smaller than a "beam" commonly used in systems with one way spans and multiple members, such as a beam and slab system, with one way slabs spanning to joists which carry loads to beams and girders.

From the width of your members, it would seem that you are working with a joist, but definiing the qualifications of the US codes would be easier by purchasing them from

http://www.concrete.org

If your code has no similar reference, having the US code could help justify or explain your reasoning.

Best of luck,

Daniel Toon

 

[csd72]

dcnnng,

If this is a continuous beam then be careful of the slenderness - there should be a limit in the code.

csd

 

[dik]

Did a microprocessing lab with a grillage of 8x48 beams @ 2' o/c spanning 18'(clear 15'), and used a single 25M T&B... with single leg stirrups...

Dik

 

[apsix]

From what I can see, from a BS8110 perspective, the minimum limit for the no. of tension bars in a beam is only governed by the rules for bar spacing and distance between bar and beam side face.
For a 6" wide beam a single bar is close enough to each of the side faces to ensure crack control. Refer BS8110; Section 3.12.11.2 .

 

[dcnnng]

csd72,

It is a continuous beam satisfying the code limit of the slenderness for beam.