Being in the proximity of the Mississippi River, this is some sort of raised floor system due to flood plain location. It seems that after a past flood the homeowner had to rebuild/repair. The city probably required a higher floor level before approving repairs, etc. This system looks very "cheesy". A low cost alternative to raising the whole house as should have been done. After the heavy flooding over the last 2 summers, FEMA made some requirements to building elevations in some flood plain locations. Also, flood insurance is much cheaper if these new floor heights meet certain criteria. I may be off base here, but that seems to be the logical conclusion here. I have never seen this system, A preferred system would have elevated the entire house and not built a system inside the walls to meet these height requirements. Roughly $150,000 repair if done correctly. Some Goverment programs picked up 75% of these repair costs.