Maximum number of Bars in Beam
Maximum number of Bars in Beam
(OP)
Does anyone have something handy to find out what will be the maximum number of bars in beam as per ACI 318-05. In case. they do not fit in one layer than what are the if and buts for second or higher layer, stirrups requirements and detailing.
Thanks.
Thanks.






RE: Maximum number of Bars in Beam
How many bars in what size beam are you looking at?
RE: Maximum number of Bars in Beam
RE: Maximum number of Bars in Beam
18" wide beam, 9 - #9 bars.
RE: Maximum number of Bars in Beam
RE: Maximum number of Bars in Beam
RE: Maximum number of Bars in Beam
1. The physical constraint due to beam width, clear concrete cover, bar size and bar spacing.
2. Maximum reinforcing allowed to achieve ductile failure mode (<0.75 balanced reinforcing ratio. For practical concerns, 0.5 is usually used in lieu of 0.75.)
When more than one layer of bars are to be placed, the effective depth reduces, the strength gained by adding bars sometimes are not very significant compared to the loss in ductility, and a lot of headaches such as difficulty in rebar placing and concrete pouring/consolidation. Also to be noted, the study on behavior of concrete beams with layered/boundled bars is very limited, if any. So, try to increase the beam size first if you can.
RE: Maximum number of Bars in Beam
RE: Maximum number of Bars in Beam
You can indeed theoretically get 6 #9s across but laps or column crossings might pose additional challenges if all your clearances are set to the minimum. Sometimes going to fewer bigger bars helps, sometimes it doesn't.
I have been guilty of specifying bars thinking that there was plenty of room and then getting to the field to see what a challenge the bar arrangement turns out to be.