EFFECTIVE LENGTH FACTOR CONSIDERING SEMI-RIGID CONNECTIONS

摘要

The usual practice in making general conclusions requires large number of examples to be carried out and then studied and analysed. However some tendencies can be clarified analytically or will appear in all numerical examples as a rule. The following conclusions can be summarised: 1. Alignment chart method is a reliable tool for K-factor evaluation in semi-rigid frames. Its application can successfully be extended in this area taking into account that the stiffness of the connections is finite and flexibility can be accounted for by some modifications. There exist possibilities to improve the accuracy of the method by varying the boundary conditions. 2. For semi-rigid braced frames with R- and V-connections the influence of V-flexibility is negligibly small. The influence of R-flexibility on the K-factor is greater in frames with strong beams-weak columns. 3. For semi-rigid unbraced frames R-flexibility and V-flexibility affect the K-factor. This influence is found to be large enough to be taken into account in the design with big care although the dissipative properties of the structure are improved. 4. Interaction effect between R- and V-type of connections may lead to considerable increase of the K-factor. The use of combined semi-rigid connections should be considered with care from stability point of view.