Removal of lally column in lower level of split entrance house.

[kallbee]

I am in the process of refininshing my basement and would like to remove one lally column.
The house is a Split Entrance, with foundation measurment of 24' x 42' (exterior)
All floor joists are 2x8 (x 12' long, thus do not runn past over the main beam)
Main beam is 3) 2x8's spiked together with slices in the center section at 7' - 21' and 35'. Splices on the outside sections are at 14' and 28'.
Beam is on centerline of foundation
Knee wall is stick built 2x4 construction and lally columns are about 7' o.c. (5 of them).
Have head room (6'-8" headroom under) for max of 11-1/4" deep laminated beam.

I would like to:
LEAVE existing beam in place
Add glulam/paralam/plywood box beam to either side of said beam to span to second lally column (at 14' from ext. of foundation)
Beef up the 30x30x12 footing, if required
add new columns, (in line with existing column at 14' form ext. foundation), as required
and REMOVE the lally column at 7' from the ext. of foundation.

As I figure it, if I beef up the gable end knee wall to 2x6 where it supports the new beams (increase bearing to 5-1/2&quot, and add 6x6 posts next to the lally I'm leaving (at 14' from the ext. of the foundation wall), the simple span of each new beam will be > 13'-2".

Does anyone know which type of beam would be best to span this new opening which will require an 11-1/2" or less depth? If my idea is not valid as it stands, any other suggestions as to how you may have solved a similar situation?

Thanks in advance,

 

[ishvaaag]

If you only have 11.5" structural depth you will have to go with it in flexure. Being for residential work, it is likely woodwork or in the worst case steel work plus if required foundations change will be enough to solve your problem at a 4 m or so span.

All amounts to a proper structural sketch of your setup and loads, foundation included, and then check the projected reforms.

The question is that I practice in Spain, in more than imperfectly understanding your description. Let's see

30x30x12 footing (difficult to revamp, lateral additions), not much thick it seems. Are these the starting footings for the new posts?

What would be the total (in plan, or if you want, in section) dimensions of your presumed final posts?

Is the total structure loading to rely exclusively in the new beam (whatever its nature)? Then if you use the existent for transfer will need to be efficiently fastened to put the new under load.

Is in some way the lateral resisting system affected by your change? (this question you may not be properly able to answer if you lack basic structural formation). If it is complementary measures may be required to be implemented, in more of those that you envisage.

For all these reasons it will be best you enlist professional work for your reform, since even well meaning without seeing we may in any addtional advice forget something relevant to the task.