This study presents a nonlinear analysis for square reinforced concrete (RC) foundation slab with bars used with both unsaturated and saturated soils in order to investigate, which response is affected by loading. Different parametric studies are undertaken in this study to determine the effect of load-displacement relationships for RC member or foundation with different cases such as (the distance of bars, diameters of bars reinforcement, types of reinforcement bars steel bars and geogrid reinforcement, yield stress for reinforcement and modulus of elasticity with compressive strength for concrete). A finite element model by ABAQUS software program is used to predict the load versus vertical displacement response of the tested RC foundations with soil by using other researchers´ experimental results. The present finite element models account for the constituent load-displacement behaviour between the RC foundations with soil and the effective load. The numerical results were compared with the experimental results obtained from other research, and good correlations were obtained. The models developed in this study can accurately capture the behaviour and predict the load-displacement of RC foundation with soil. This study shows that geogrid reinforcement enhanced the capacity of the foundation or member when used with different ratios of steel bars in soil and this provides a sustainable solution by reducing steel reinforcement. This geogrid ratio the reinforcement, while the member in saturated soil

is less strong than it when in unsaturated soil.