Virtual Beam In The Design Of Elastic Foundation Beam

At present the interaction between soil and foundation is one fundamental problem of the study about structure of foundation and underground building, it is also a important problem in the designer of structure. Because the contact pressure between soil and foundation is a basis in the designer of structure, so it is also the center of the study about interaction between soil and foundation.As the Winkler's model, the contact pressure is proportional to the deformation of soil. Then it is easy to design foundation beam. But it is not take proliferation of the contact pressure into account. The soil is composed of two parts, the one is below foundation and the other is out of it. The traditional ways that how to design foundation beam as Winkler' model only consider the influence of the one below foundation, but don't include the influence of the other's. They assume that the heads of beam is free, but in fact, it is not so. In fact, the part soil which is below foundation and the other is unity, they all should be considered. Here we extend the beam; the extended beam is virtual beam. We use the virtual beam to replace the influence of soil which is out the foundation. After that, we make linear differential equation group and use RAGA to ascertain the deformations of virtual beam. Then we can work out the deformations of beam and the contact pressure. We also analyze the relationship between parameters EI,K,G,loading and parameter of virtual beam. Finally, we compare the results of ours with Winkler's,Double parameter model's; the ours is more reasonable, find that our result is more reasonable .