×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Free-standing reinforced Beam-Column

Free-standing reinforced Beam-Column

Free-standing reinforced Beam-Column

(OP)
I am designing a free-standing beam-column that is supporting a piece of the world trade center for a memorial. It is 8" thick roughly 14.5' high. Klu/r is roughly 150. (fixed base & r=.3h) How would I go about designing this member? Should I consider it for sidesway? All beam column examples I see only have the moments applied at the tops and bottoms of the columns. My moments (lateral wind and eccentricity from the piece of steel) are not exactly at the top. Attached is a pdf of memorial.  

-Robert Miller, E.I.T.
KPA Structural Engineers

RE: Free-standing reinforced Beam-Column

You can proceed along the AISC guidelines for design in AISC 360-10 Chapter C, mainly section C2.

Essentially you need to consider initial imperfections, both in-member P-delta and structural P-Delta, better subdivide your column in segments for a more ensured consideration of P-delta effects, use a reduced stiffness, and use beam column checks from the code.
 

RE: Free-standing reinforced Beam-Column

Is this a pair of concrete walls that are supporting the piece of steel?

It looks like perhaps one of the walls actually supports the steel and could be designed as a concrete beam/column.  Simply apply your loads and check the Pu and Mu combinations of values at various heights for a rectangular column.

RE: Free-standing reinforced Beam-Column

That is, JAE, ewinforced! I found strange not finding the (steel) beam-colum in th sketch. By the sketch it looks as stiff as to safely proceed as you indicate.

RE: Free-standing reinforced Beam-Column

(OP)
The beam-column is the pair of concrete masses. My main concern is the P-delta effect and how to assume bracing or limit deflection to make P-delta negligible.

-Robert Miller, E.I.T.
KPA Structural Engineers

RE: Free-standing reinforced Beam-Column

If so massive P-Delta must be small. But you can always subdivide the column in segments of reduced flexural stiffness, particularly if the solicitations are to such level that such reduction of stiffness is to be present, this way you will be capturing most of the effects of the structural and in-member P-Delta with one P-Delta able program, or you might work iteratively with one that is not. Start from some bad geometrical imperfections and then you can check the segments after the stable equilibrium with the ordinary equations. Respect the stiffness ACI 318 used to have statements on how to proceed depending upon the hypothesis being considered (I don't practice by it, in Spain).

RE: Free-standing reinforced Beam-Column

Are these precast panels? If so then someone will need to check them for lifting stresses and anchorage loads.

Due to their thinness I would treat them as walls and see how that works.  

For this level of load I would normally ignore the axial load and check for bending only. Pdelta effects require a significant P, which you do not seem to have.

Also ensure that you have allowed for people hanging off this thing in your calculations - it will happen.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources