huangyhg

stirrups placement in cantilvered beams
as per attached sketch, please suggest the best arrangement and orientation of rebars and stirrups in cantilver beam. beam is also supporting a secondary beam at the tip of cantilver (not shown in sketch).
appreciate for guidance.

i swould still use "b" as the diagonal tension crack does not know whether the "beam" is horizontal or sloped. it should still form roughly 45 degrees relative to the main axis of the cantilever.
mike mccann
mmc engineering
i would have said c because the direction of the shear load is still straight down
i would use 'b' for the stirrups as the gravity load will be seen as axial and perpendicular components by the beam.
top bars; obviously anchorage into the column is crucial and use laps as far away from the column as possible.
mike is correct. the stirrups must be oriented so that a diagonal tension crack will intersect the reinforcement. a diagonal tension crack in the inclined member would tend to be roughly vertical for downward loading, and roughly horizontal for upward loading. so orienting the stirrups perpendicular to the
what is the mechanism that causes the crack to be oriented to the beam orientation?
is that the same for a flat cantilevered beam with a tapered soffit?
the mechanism of shear failure is actually tension in the concrete, and this tends to occur diagonally across a member. nothing is precise in concrete, but we assume that diagonal tension causes cracking to occur at 45 degrees to the member axis. yes, this applies to any
option b & c are ok options. the stirrups don't necessarily have to be in line with the loading. i.e. they can be diagonal. draw out your strut& ties on each model. graphically represent the force flow like a truss. make sure the compression strut is within 30-45 degrees.
b is better. as noted by others, c stirrups are too much aligned with potential diagonal tension cracks.
your column/beam connection is critical here. i would make the cog a large hook, and have well anchored bars running perpendicular to the crack that will form at the internal angle.
thanks for all.
is there any reference material for beam reinforcement in tapered sloped cantilver beams.
i have to use arrangement "a", type "y" for varying stirrup sizes, otherwise each stirrup have to be made different. two stirrup legs should have development length to act as one.
does your code allow lapped splices in beam shear reinforcing? the australian code as3600 does not accept that lapped splices provide adequate anchorage unless they are welded splices.

__________________
借用达朗贝尔的名言：前进吧，你会得到信心!
[url="http://www.dimcax.com"]几何尺寸与公差标准[/url]