How much reinforcing in a concrete lintel?

[concrete]

Hi guys, not posted in a while, but I'd like a bit of advice on a lintel.

I'm a small scale concrete products manufacturer and I've been asked to make a fairly large lintel. I've made plenty of smaller lintels over the last twenty five plus years with no problems and I'd like that record to continue.

The lintel I've been asked to make is 2340mm wide by 325mm high by 230mm deep. I was going to use 6, 20mm rebars welded together to form a cage and would like to know if that is enough. Reading up on various sites, I'm amazed at how small bars are advised to be used.

The mix I've used over the years by volume is 2 parts coarse aggregate, 1 part concreting sand, 1 part cement. I also add fibres to the mix. I use Southern Cement which is 52/N Rated.


I've posted a couple of photos to give people an idea of the load it's got to take.

Thanks in advance.

 

[noseall]

Does it need to take the entire weight of the basketball hoop?

 

[concrete]

Does it need to take the entire weight of the basketball hoop?

You should be on the stage.

 

[RedHerring2]

These were the lintels that I made for my house restoration in France:
View media item 37389The rebar I used was 12mm, 10mm and 8mm.

and the house:
View media item 25584 View media item 25585
I took my advice from a site that showed how rural buildings were maintained. If I can find it I'll post a link.
Voila:
http://www.autonopedia.org.uk/buildings_and_shelter/Rural_Building/Lintels.html

Edit: Looking closely at the picture there is a possibility that my memory is suspect. It could have been 12mm, 8mm and 6mm bars.
Also, looking at your comments about bar thickness, the bar is in tensile stress, especially the lower bars, not bending stress, hence the requirement for thinner bar.
The web site quoted illustrates this well.

 

[Static]

The reinforcement should be such to take the loading on the lintel, both the moment and the shear.. get it designed and detailed..