• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.19 no.3 s.73
• /
• pp.303-312
• /
• 2006

This paper presents the equivalent nodal load for the element stiffness which represents the influence of the stiffness change such as the addition of elements, the deletion of elements, and/or the partial change of element stiffness. The reanalysis of structure using the equivalent load improves the efficiency very much because the inverse of the structural stiffness matrix, which needs a large amount of computation to calculate, is reused in the reanalysis. In this paper, the concept of the equivalent load for the element stiffness is described and some numerical examples are provided to verify it.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.16 no.4
• /
• pp.439-450
• /
• 2003

Flat plate system has been adopted in many buildings constructed recently because of the advantage of reduced floor heights to meet the economical and architectural demands. Structural engineers commonly use the effective beam width model(EBWM) in practical engineering for the analysis of flat plate structures. However, in many cases, when it is difficult to use the EBWM, it is necessary to use a refined finite element model for an accurate analysis. But it would take significant amount of computational time and memory if the entire building structure was subdivided with finer meshes. An efficient analytical method is proposed in this study to obtain accurate results in significantly reduced computational time. The proposed method employs super elements developed using the matrix condensation technique and fictitious beams are used in the development of super elements to enforce the compatibility at the interfaces of super elements. The stiffness degradation of flat plate system considered in the EBWM was taken into account by reducing the elastic modulus of floor slabs in this study. Static and dynamic analyses of example structures were performed and the efficiency and accuracy of the proposed method were verified by comparing the results with those of the refined finite element model and the EBWM.

• Journal of Korean Society of Steel Construction
• /
• v.23 no.5
• /
• pp.535-546
• /
• 2011

In this paper, semi-rigid elasto-plastic post-buckling analysis of a space frame was performed using various explicit arc-length methods. Various explicit arc-length methodsand a large-deformation and small-strain elasto-plastic 3D space frame element with semi-rigid connections and plastic hinges were developed. This element can be appliedto both explicit and implicit numerical algorithms. In this study, the Dynamic Relaxation method was adopted in the predictor and corrector processesto formulate an explicit arc-length algorithm. The developed "explicit-predictor" or "explicit-corrector" were used in the elasto-plastic post-buckling analysis. The Eulerian equations for a beam-column with finite rotation, which considers the bowing effects, were adopted for the elastic system and extended to theinelastic system with a plastic hinge concept. The derived tangent stiffness matrix was asymmetrical due to the finite rotation. The joint connection elements were introduced for semi-rigidity using a static condensation technique. Semi-rigid elasto-plastic post-buckling analyses were carried out to demonstrate the potential of the developed explicit arc-length method and advanced space frame element in terms of accuracy and efficiency.