Alternatively, zero-length external connector-elements can be used in the mesh structure, but this will complicate both mesh definition and assemblage operations.
However, adding such features to a FE model would require additional theoretical effort in the element development process. The usefulness of Finite Element (FE) models for many engineering purposes depends on the element's ability to support a variety of end-connection types including releases and partial-fixities. Their comparison with the results of FEM analysis was provided. The obtained results are illustrated in detail on a numerical example. For introduced rotational rigidity of realistic connections, the expressions for determination of bending moments at ends of semi-rigidly connected elements have been derived as well as conditional equations for determination of deformation-unspecified values at static load by first-order theory.
Due to its generality, simplicity and straight-forward calculation, the method developed in this paper is convenient for both computational utilization and hand calculations. The original calculation for steel frame structures with semi-rigid connections as a function of rotational rigidity of connection, a realistic parameter for determination of both tension and deformation fields of connection as well as entire construction, has been derived in detail. In this paper, original extension of classic deformation method for global elastic analysis of steel construction with semi-rigid connections is developed. Characteristic jumps in the optimized mass versus rotational stiffness were observed. Furthermore, the structures were optimized for a range of rotational stiffness, where all connections in the structure were assumed to have the same rotational stiffness. The VWOM produced results up to 26.7% lighter than results in the literature. Two case studies are considered: (i) a three-storey two-bay and (ii) a four-storey three-bay office building. The example of a pitched roof frame is used to explain the method. The rotational stiffness of each connection can be varied form rigid to pinned. Connections are modelled using rotational springs, allowing some moment transfer. In the optimization process, members are selected from a discrete database to meet all strength and stiffness criteria. The VWOM is an automated method that minimizes the mass of a structure with a given geometry, multiple deflection criteria and load cases, while adhering to Design code requirements. In this paper, the virtual work optimization method (VWOM) has been generalised to consider structures with semi-rigid connections.
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