Designing and Building Foundation Over Ground - Foundation Over Hard Ground Floor

[AshiqRumi]

Hello Everyone,

Currently i am working on 4-Storied School Building Project where a senior structural engineer is taking care of the structural issues.

Last day he has sent me a drawing where i found the foundation is placed over ground on compacted sand.

here the soil is stiff clay but he didn't recommended any soil test as his philosophy is to place the foundation as a combined plate and as the soil is very dense, dry and stiff, it won't be subjected to settlement. but my point of view is, if the foundation is over ground then when the structure will be subjected to seismic force, foundation plate might displaced along the force direction. if it is under ground then will definitely have a fixity which would be better than his proposal. moreover, this type of foundation plate design is increasing the reinforcement (as well as cost) which could have been solved by isolated footing by reducing the reinforcement . the location of the building is at moderate seismic zone.

i have attached the foundation drawing along with the picture ground/soil condition
please let me know about your opinion.