Concrete Column Failure 1

[mijowe]

If a concrete column, circular with ties, fails in compression, or compression and bending, is there any reason to believe that the direction the bars buckle would give any indication of the reason it failed? Are the bars expected to buckle radially, or are they just as likely to buckle in random directions? If the failure was combined compression and bending, would the bars be expected to buckle in the axis of the moment?

 

[hokie66]

I think the direction in which a bar buckles would depend mostly on the restraint condition of that particular bar. Amount of cover, location of tie hooks, etc. could contribute. If subject to significant bending, the bars on the compression side would probably buckle first, but not necessarily in any particular direction.

 

[paddingtongreen]

I pretty much agree with hokie66. I would add that if the bars on one side are buckled more than the opposite side, it does not necessarily mean that bending was involved, only that it probably was. Concrete is not completely homogeneous.

Further. Time may be a factor, the bars on one side may have started to buckle on one side, perhaps cracking but not spalling the concrete; and then the other side may have started later under moment reversal. Repetitions could cause damage with the appearance of axial load failure.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[Ron]

I agree with both of the above, particularly Michael's comment on the timing. Once the initial failure occurs, the stress distribution goes haywire and then the failure manifestation might not appear to follow "classic" conditions. As they both pointed out in different ways, concrete is not homogeneous and its placement certainly contributes to that. A bit of poor consolidation, a spot of oil on the rebar...all of these contribute.