engleski

Dynamic Analysis of Long Structures Supported by the Ground under Moving Loading by Finite Strip Method

Modeling of long structures supported by the ground and under moving loading, such as railways and airports, is very complex work, which combines several numerical models: structure model, ground model and loading model. Usual engineering practice in analysis of structures supported by the ground and under the influence of a moving loading is to use Winkler model. This model has several drawbacks : does not allow propagation of transversal waves but through the structure, because shear stiffness is not included ; ground deformation is present only under the structure, there is no deformation beyond edges of the structure ; linear relation between applied load and displacement. Undesirable consequence is wave reflection on the structure, which induces very high frequencies. This paper describes models developed for dynamic analysis of long structures subjected to the moving load and lying on the ground having endless boundary conditions (no reflection of transversal waves). Ground has been modeled as Pasternak foundation that takes the shear stiffness into account. The models allow propagation of the transversal waves also through the ground with the advantage that the same model is applicable in both static and dynamic analysis. Structural modeling adopts two approaches : i) beam model based on quarter point beam elements, supported by the Pasternak ground model, ii) finite strip model with equal boundary conditions [2]. Moving loading is described as moving force or moving mass enabling the comparison between them. Loading is time and velocity dependent. The later one requires more effort and the newly developed Impulse Acceleration Method has been adopted [1]. Several numerical examples enable insight into quality of the results obtained and provide comparison between the various assumptions.

dynamic analysis; long structure; moving load; finite strip element; endless beam; Pasternak soil

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