Jib crane column stability

[Isfakul]

Hi,
I am trying to change an existing overbraced jib crane to a new underbraced jib to gain more head room. The manufacturer has chosen 2ton, 2.5m 180 degrees swing manual hoist jib as we required. However their basic engineering checks has determined the support column which runs from bottom floor will have perpendicular defelections as well as in the slewed direction.
We really cannot change the support column and need the extra headroom to lift a pump actuator (current underbraced design cannot lift due to less room).
The totoal length of column is around 5.5m.
What structural changes to the column can help witht this? Or changing the underbraced support length will help?

 

[Isfakul]

More images.
The column runs through the platform to the ground

 

[robyengIT]

sure is it not possible to connect the support column to the wall, so to shorten the free length or to change the top restraint ?

 

[Isfakul]

Hi robyeng, if you look at this attached picture, the colum is bolted to the wall behind.
Do you reckon the colum would require additional support?
The jib is to just lift the pump actuator and do maintenance and worse case drop it to ground for replacement.

 

[robyengIT]

if I well understand : fig 1 = existing fig 2 : what you want (as far as I understand)
The only problem, for me, is the detail T (from tension to compression, furthermore is is obstructing the displacement of the crane.
Column C : if it is deflecting, it can be stiffened welding some plates to modify the profile so to become a box
Beam HB : it can be stiffened adding plates on top or adding a similar profile on top (that is doubling the beam)

PS : without any size, sketch or more details we can't help you

 

[le99]

My understanding is in-line with @robyengIT's comment. If there is no headroom limit near the column, you may explore the possibility to add a strut below the jib arm. The column might still need strengthening though.

 

[HTURKAK]

Yes it will help.. I attached the deflected shape sketch drawn on robyengIT picture. If you connect the column from the top level to the wall , it will help.

Strengthening of the column can also be considered.

 

[Isfakul]

@robyengIt i have attached the design i have selected to go with for my underbraced jib.
Current results by the manufacturer indicate that allowable deflection is exceeded in both the perpendicular and slewed direction, and so the existing column is not suitable for the i installation.
The problem is since its in underground mine site, options are limited but what sort of modification can help strengthen the column ro support this new jib?
Since its fixed bolted to ground, will bolting to back wall in another length or extending the column by welding extra bit on top so it can be bolted to top wall can be helpful?

 

[robyengIT]

possible solutions for column stiffening (in red)

 

[Isfakul]

Hi @robyengIT thanks mate.
So possible plates on both side of the column for the whole length (or Atleast till the platform) and stiffened from the plates to wall bolted?
You reckon further stiffening/ modification in the ground too?

 

[robyengIT]

if you have stiffeners to the wall all along the column, you don't need anything more on the ground

 

[Isfakul]

@robyengit thanks mate.

 

[Isfakul]

Hi @robyengit,
I was thinking of welding a few plates like this and bolting it to wall as your picture.
Instead of making whole column like a box, putting 5 plates welded both sides and stiffening to wall might be more economical.
What do u think?

 

[human909]

I think you are the engineer and need to make a few engineering choices yourself and back it up by suitable calculations.