Safety, optimisation and the sustainability are the most important aspects for the design of any foundation system. An optimised and safe design of foundation systems for high-rise structures in difficult soil and groundwater conditions is based on a reduction of construction material used, construction time spent, energy consumed and the adequate consideration of the soil-structure interaction. This is also important for the high-rise structures like skyscrapers and bridge piers in Dubai, UAE. Due to the large loads most of these structures are founded in the Dubai sedimentary rock. Up to now the rock mechanical parameters for these rock layers have been defined on the very conservative side which led to over-dimensioned foundations in many cases. In a large research program the bearing behaviour of Dubai Sandstone and Dubai Siltstone has been investigated by field and laboratory tests, by in-situ pile load tests and the numerical back-analysis using the Finite-Element-Method (FEM). The comprehensive research investigations show, that the stiffness and strength of Dubai sedimentary rock is more than 20 times higher as it is assumed up to now. The thesis presents the scope of research, the epoch-making results and the significance for the engineering practice. The geotechnical data used in this thesis is collected from geotechnical investigation reports (195 boreholes) and static load tests (116) from more than 45 towers in Business Bay and Downtown Dubai as well as a case study evaluating one project located in Business Bay.