Reinforced concrete column subjected to impact
Reinforced concrete column subjected to impact
(OP)
Hello,
I have to design the corner column (reinforced concrete) for a two-story house at the crossing of two streets, C1 in the picture specifically.

If loads controlled the design, it would be a 20cm x 20cm column with #4 bars, like C2, etc. However, corner columns are given a special consideration due to the potential risk of being impacted by vehicles, which takes precedence over the DL + LL static analysis. It is not uncommon for corner columns of ordinary houses to have a diameter of 50cm or more (or 40cm x 40cm if square) and be heavily reinforced as well. I skimmed ACI 318-08 but didn't find anything in this regard.
Now, my questions are: What is the common practice for designing reinforced-concrete corner columns subjected to the (potential) impact of vehicles? What is the detailing like? Which shape is more convenient, square or circular? Can the longitudinal reinforcement be spliced in these columns? My intuition says it shouldn't... Is it sensitive to use spiral rebar for shear?
Thanks.
I have to design the corner column (reinforced concrete) for a two-story house at the crossing of two streets, C1 in the picture specifically.

If loads controlled the design, it would be a 20cm x 20cm column with #4 bars, like C2, etc. However, corner columns are given a special consideration due to the potential risk of being impacted by vehicles, which takes precedence over the DL + LL static analysis. It is not uncommon for corner columns of ordinary houses to have a diameter of 50cm or more (or 40cm x 40cm if square) and be heavily reinforced as well. I skimmed ACI 318-08 but didn't find anything in this regard.
Now, my questions are: What is the common practice for designing reinforced-concrete corner columns subjected to the (potential) impact of vehicles? What is the detailing like? Which shape is more convenient, square or circular? Can the longitudinal reinforcement be spliced in these columns? My intuition says it shouldn't... Is it sensitive to use spiral rebar for shear?
Thanks.






RE: Reinforced concrete column subjected to impact
RE: Reinforced concrete column subjected to impact
Beyond municipal codes, which, by the way, are non-existing in this case, I'd like to know what the criteria are for designing such columns.
Thanks.
RE: Reinforced concrete column subjected to impact
Anecdotal:
I have a friend who lives on curve where he looses his mailbox, 8' off the road, about twice a year. The last time he rebuilt it he made the inside a reiforced concrete post 2'x 2' x 4' deep. It was hit about 2 months after he finished and it tore up one car and sent the driver to the hospital. The driver had a blood alcohol twice the legal limit. He is now suing for $500,000 for lost of work, companionship, pain and suffering, etc. The suit says that the mailbox was not of normal construction and the post was deliberately setup to hurt someone.
RE: Reinforced concrete column subjected to impact
Can you define what reinforcement ratio constitutes "heavy" reinforcement.
By the way, what CAD program are you using and how would you rate the useability?
RE: Reinforced concrete column subjected to impact
RE: Reinforced concrete column subjected to impact
RE: Reinforced concrete column subjected to impact
Mike McCann
MMC Engineering
RE: Reinforced concrete column subjected to impact
According to a few local contractors, they build these columns 40cm x 40cm with 16 #5 (As/Ac=0.02). However, that's not the most widespread pattern I see. I see corner columns as slender as 20cm x 20cm and as thick as 60cm x 60cm and everything in between (for like DL and LL).
My concern is, if something goes wrong and people get hurt, I cannot say to the judge "well, I designed it that way because of word of mouth from local contractors.." I'd better have a more formal and professional answer.
I'm using Autocad 2006 with its built-in 3D & rendering functionalities. When needed, I download textures (plain GIF/JPG/BMP files) from the internet. Not the killer user experience, but that's the only package I know. There are many 3D authoring apps that I would like to learn, some commercial (e.g. 3D Studio Max), some free (e.g. Blender). Too many things in the TO-DO list and too little time unfortunately. I do post-processing (like adding dimensions and text) over the rendered model with Photoshop.
What would you change in the following design ? Too much congestion at the encounter of both beams doesn't leave room to interweave the rebar. Does it make sense? (see pics.)
Thanks.
RE: Reinforced concrete column subjected to impact
RE: Reinforced concrete column subjected to impact
RE: Reinforced concrete column subjected to impact
RE: Reinforced concrete column subjected to impact
RE: Reinforced concrete column subjected to impact
Impulse and momentum methods can be overly conservative, as it is a fair bit of work to look at anything other than a direct head on impact.
RE: Reinforced concrete column subjected to impact