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| Euqivalent Element Representing Local Flexibility of Tubular Joints in Structural Analysis of Jacket Structure of Offshore Platforms |
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| DOI：10.7511/jslx19923043 |
| KeyWord:structural analysis, finite element method, local flexibility of tubular joints, offshore platform, tubular steel structure, |
| Hu Yuren Chen Bozhen Ma Jumping |
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| Abstract: |
| At the tubular joint of a jacket structure of an offshore platform, the chord wall of the joint will deform locally after loading. Therefore, when the structure is analysed as a frame, beam elements are not rigidly connected at the joint. The local flexibility of tubular joints caused by the local deformation of the chord wall should be taken into account in the calculation. An equivalent element representing the local flexibility of tubular joints is developed in this paper, which can be used in the finite element analysis of the jacket structure of offshore platforms. The charactristics of local deformation of tubular joints under axial force and inplane bending moment can be effectively modeled with the equivalent element. Stiffness matrices of the equivalent elements for T-,Y- and K-type tubular joints arederived. which can be established after evaluating the values of the local flexibility by using parametric formulae. The equivalent element can easily be used together with the general FEM program, such as SAP5, to perform precise static and dynamic analysis for the jacket structure of offshore platforms. A preprocessing program for automatically generating data of the stiffness matrix of the equivalent element, which coincide with the input format of the readin-stiffness element in SAP5 element library, has been developed. A simple example is given to illustrate the practical use of the equivalent element. The results show that it is necessary to consider the local flexibility of tubular joints in the structural analysis of offshore platforms. Comparison of the results by using a model involving the equivalent element with those from a FEM calculation is also given. which indicate that it is viable and accurate to employ the equivalent element in modeling the local flexibility of tubular joints. |
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