Beam Loading Question
Perhaps the columns are resting on a slab cement floor? This would act to spread the load to the slab then to the the ground below, or to the wal bearing footers. I am not familiar with the codes as to whether a footing directly under the column four feet below the ground level is required.
But the columns are necessary to support the load from above - your 1 inch deflection over 15.5 feet jumps to over a foot deflection for a 28 foot span, assumming the entire flooer load is carried by the one beam and the adjacent bearing walls. are there other support beams?