SIZING FOR VERY LARGE EQUIPMENTS

[hanxi]

I'm designing two (2) horizontal vessels that are to be installed on top on a structure. The loads are very large ( Vessel 1: empty=78ton, operating=497ton, test=512ton and Vessel 2: empty=48ton, operating=239ton, test=254ton) that made my supporting members (at fixed and sliding sides of vessels) failed. I've already use the maximum member size that our fabricator can produce H-800x300x14x26 for beam and H-428x407x20x28 for column (depth,width,flange and web dimensions in mm). Refer to attached image for the beams and columns that failed. My senior suggest to use BOX COLUMN and BOX BEAM. Can anyone suggest detailing of these BOX COLUMNS and BOX BEAMS... Or do you have any idea like using BUILT UP COLUMNS and BEAMS instead of TUBE MEMBERS (box column and beam)? Can you also suggest its connection details? Any comments and suggestions are greatly appreciated. Thank you so much.

HANXI

 

[civilperson]

These maximum sizes are much smaller than are available elsewhere. If you are constrained to ONLY use the specified fabricator, then I suggest that you add plate to both flanges, 350 x 30 with continuous 13mm filet welds and doubler plate to one side of web, 675 x 20, and stiffener plates to the other side of the web with coped corners and flange and web welds. Using moment restrained connections at both ends of all the beams with similar strengthening of the columns will suffice if spans are limited or shortened using diagonal brace to the beam being loaded.

 

[kslee1000]

civilperson has very good suggestions to beef up the beam and columns. Here are my 2 cents:

1. Add bracings in both horizontal and vertical planes to reduce unbraced length to gain some strength.
2. Consider to use deep build-up girders in the long direction to allow for ample space for connection.
3. Consider to add bull legs (brackets/corbels) to the ends of the beams supporting the equipment.
4. The columns can be beefed up by plates as suggested, or add channels and angles to the flanges thru weld/bolt/revit to gain additional strength if necessary.

The feasibility of providing sound, easy to install, connections on the box section needs to be evaluated prior to any changes.

 

[saplanti]

From the image, it seems that there are some stability issues:

1. I suggest you to move the loaded beam ends close to the column centres. This will reduce the required main beam sizes.

2. In this kind of structures, the major loads are the vessels themselves. Therefore the structural member arrangement should follow the requirement of the vessel support needs. So the column arrangement may need to be changed to suit the vessel requirements in case there is no other issues under/around structure or they should suit the vessel needs. The wind/seismic loading will require enourmous bracing in vertical and horizontal. The bracing will reduce the column effective lengths and you may be able to use the available largest column size you have. Otherwise, your manufacturer should give you square column sizes that they can manufacture.

3. You need to take the torsion on the primary support beams that comes from vessel horizontal thermal/wind/seismic loads by using appropriate bracing members in horizontal. These bracing members against torsion may/will reduce the effective length for primary load carrying members, in this case deflections may be the only issue to be taken care off.

Hope it helps.

Ibrahim Demir