| Grillage girder is always used for analysis the structures, such as dense ribbed slab, superstructure of bridge and grid-mat foundation. In this paper, a mechanical model for grillage girder by elastic supporting is proposed, and used for analysis the track structure for the first.There are two parts in this paper.The first part, which includes Chapter 2 and Chapter 3, proposes and studies the static force solution of the model for grillage girder by elastic supporting, some applications are discussed.In Chapter 2, proposes an analytical model to the grillage girder, and then establishes its equations by force method. For the primary structure, the upper longitudinal beam is regarded as the finite length continuous girder by elastic point supporting, and the lower cross girder is regarded as the finite length beam on elastic foundation. A computing program is made by Qbasic language.In chapter 3, studies the applications of the model to the track structures, which is feasibility by compared with the other algorism of the track structure. Because of established the space layered model for the track structures, It shows some advantages at present.The second part is the Chapter 4, studies the dynamic responses. Firstly the dynamic analysis model is established by the method of lump mass, and then analyses the free vibration frequencies and corresponding modes by the method of QR. The program for analyzing the vertical vibration of ballasted track and slab track is drew up. The conclusions show that the basic vertical free vibration frequency of the track structure is much higher than the external exciting one, so the resonances can not occur in practice. At last, the force vibration of the model is discussed by the method of principal mode superposition. |
