Blade columns?
Blade columns?
(OP)
I have been engaged in design of "blade columns", which is the term they used (probably an architect's term) for walls that were used for its thinner dimension compared to normal RC columns. I'd like to ask if anyone knows any specific guidance from codes or texbooks that specifically identifies the behavior of these types of "columns". I know its basically just an RC wall by design but the frequency of its use in our projects invoked me to think that there is more to be looked at on this types of columns.






RE: Blade columns?
The only issue that I can see that doesn't apply to typical R/C columns is the consideration of slenderness.
RE: Blade columns?
Blade columns have to be designed using the provisions for walls unless they are thick enough for two layers of vertical bars, restrained by ties, in which case the column provisions can be used.
RE: Blade columns?
In terms of strength design, they are normally columns to get the extra capacity from full design of a column compared to the simplified design method for walls.
RE: Blade columns?
From the design we've made, the "blade columns" were checked for the amount of lateral force it carries. Though we've found out (from calculations and analysis software) that they only carry less than 20% of the lateral force, it was quite fair to think or ask, what if they did carry substantial lateral amount of force? If they do, they no longer qualify as bearing type but instead are now shear walls. For zone 3 or 4 as shown in the UBC, special detailing is required for shearwalls though this is quite a task (and expensive) considering the amount of additional shear reinforcement for boundary elements.
Another difficulty is that these walls are offset all the way to the top in different lengths per story. In some cases, the wall below is shorter than the one above.
Thank you all for your replies.
RE: Blade columns?
RE: Blade columns?
I have seen blade columns used to introduce a stiff element into the lateral force resisting system. For example, a suspended slab supported by 450 diameter columns (18") with blade columns around the perimeter to stiffen the structure laterally.