Field tests are: Standard Penetration Test (SPT), Cone Penetration Test (CPT) and van shear. The laboratory tests that define the shear strength (bearing capacity parameters) are: direct shear, unconfined and Triaxial. The bearing capacity of soil for any site can be determined from the soil tests (field and laboratory tests). Figure 2 shows the theoretical vertical stress distribution under a square footing and pile foundation on the ground surface. The influence depth of soil under foundation depends on its width. The stress distribution that influences the stress zone under the foundation is to be considered for both shallow foundations and deep foundations. The contact pressure between the lower face of the shallow foundation and the implied soils is the bearing pressure. Spread foundations are mostly used in medium and small size structures, on moderate to good soil site conditions. Raft foundations are often used for larger structures when the soil has differential settlement problems and the foundations are to be under the ground water table. Finally, for Basrah region, shallow foundations were an appropriate selection, but for most areas deep foundation was the right choice. For Baghdad region, shallow foundation was more suitable for building not higher than five stories. The results obtained from the average and worst bearing capacity indicated that for Mosul, we could use shallow foundation (spread and mat used if there was basement) for different areas and for buildings with many stories. In addition, the worst bearing capacity values were also used for the three regions (Mosul = 77 KPa, Baghdad = 68 KPa and Basrah = 24 KPa). The average values of bearing capacity in each region were applied in the program (Mosul = 177 KPa, Baghdad = 125 KPa and Basrah = 84 KPa).

Then, the model of a building was designed (two floors, with mat foundation type) using STAAD Pro software. The results obtained were used in the application of the general equation of the bearing capacity. The values of the bearing capacity parameters (ϕ and c) were obtained from the above tests. They were subjected to the following testes: Atterberg limits, sieve and hydrometers, consolidation, direct shear, unconfined compression and the filed (SPT test). The samples were collected at varying depth between 1 to 24 m. Seventy nine samples were collected from 23 boreholes at three different locations (Mosul at the North, Baghdad at the middle and Basrah at the south of Iraq). This research is to study the effect of bearing capacity on shallow foundations in different regions of Iraq. These differences in soil affected the process to select the suitable type of foundation. Most of Iraqi soil is classified as Quaternary deposits, especially in the Mesopotamian plain and tributaries of the River Tigris.

Foundation design in staad pro