engleski

Beam model for creep buckling analysis

Columns under sustained loads are generally unstable in the regime of creep. That means that loss of stability may occur during a period of exploitation of structure even for loads lower than critical buck-ling load. Due to that reason stability is characterized by critical buckling time defined as load dura-tion for which buckling deflections becomes infinitive. In this paper a one dimensional finite element for geometrically and materially nonlinear analysis of beam structures is presents. Beam members are suppose to be straight and prismatic and of rectangular cross section. Spatial displacements and rotations are allowed to be large but strains are assumed to be small. The corresponding equilibrium equations are formulated in the framework of Eulerian descrip-tion, using the virtual work principle. Material is assumed to be homogenous and isotropic. Problem is approached through two phases. In first phase an pre-buckling behavior is modeled through load deflection manner to reach appropriate instantaneous response of structure for applied load at zero moment while in second phase an explicit time integration scheme is used to reach critical buck-ling time. For modeling creeping material behavior Norton law have been applied. Implementation of developed numerical algorithm is demonstrated trough few test problems.

stability; buckling; beam structures; large rotations; large displacements; creep; material non-linearity

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