Expert: Paul S. Brown, AIA - 8/25/2009

Question
In my basement,I have a steel 6"X6" I-beam that spans 17'4".  It is supported by one steel (3') post approximately mid way.  The post goes into the concrete floor, and I would assume that is is sitting on a per.  I would like to install two(2) post to support this beam at approximately 5 feet from each end.  The new (steel) post would rest on a 4" square plate and would sit directly on the concrete slab.  After putting in the two new poles, I would remove the old one.  Would this be structurally sound, and can the concrete slab support this load?  Thanks for you advise.
Tony

Answer
Hi Tony:
You are going about this the right way, asking the right questions before proceeding.  That is good.  Unfortunately, there is no way to evaluate your specific question without being on site, and observing the actual conditions (thickness of concrete floor slab, underlying soil, loading from above, etc.) I strongly urge you to engage the services of a local structural engineer, and to contact your local building department and pull a permit and comply with inspections, before proceeding with this work.
Thanks,
PB