Stiff Foundation Mat

If i imagine this same strip footing placed under 3 columns spaced few meters away and acting as 3 point loads i would say that the foundation would behave a flexible since it will start bending.

Stiff foundation mat. A stiff foundation mat below is a good type of shallow foundation which can transfer loads from locally liquefied zones to adjacent stronger ground. It is common to use mat foundation or deep basements. A mat foundation is in essence a stiff slab that acts as a single foundation element that covers the entire plan area of the structure. Mat foundation can be subjected to vertical loads horizontal loads and also to moments from column members.

Ive always thought of strip footing under the wall whoes 45 degree disperse load line doesnt pass thru the bootom as a stiff foundation. Buried utilities such as sewage and water pipes should have ductile connections to the structure to accommodate the large movements and settlements that can occur due to liquefaction. Loads on raft or mat foundation. It is a continuous thick concrete slab on the soil that extends the entire footprint of the building and increases the soil bearing capacity power.

A mat foundation is used when the subsoil is weak and column loads are so heavy that the conventional spread footings cover more than 50 of the building area. As any shallow foundation a mat foundation has to be checked against bearing capacity failure and excessive total average settlement. Strip rafts and grid foundations are also generally designed on the same principles as mat foundation.