Prestressed Foundation Beams on Elastic Layered Soil

This paper develops a systematic procedure concerning the determination of the interaction of an arbitrary multistory frame with the elastic layered foundation soil by making use only of the soil surface deformational characteristics. The paper focuses on the response of the foundation beam through which the frame rests on the ground, showing the need for prestressing the beam in order to ensure better functionality. The investigation addresses the dual goal of excluding the undesirable cracked state of the beam and reducing its structural height together with the overall amount of reinforcement needed. A set of soil layered profiles is considered and it is investigated to what extent the required prestressing force depends not only on the soil deformational properties at hand, but also on the method of analysis used. The results are compared for both the elastic half-space and the Winkler's method, taking into account either the whole structure stiffness, or the stiffness of the foundation beam only, as it is usually considered in practice.