The support between the steel frame and shear-type bracing, the mutual support between the same layer columns and the inter-story interaction should be considered for overall stability calculation of multi-story shear type braced steel frames. The effective length coefficient method in the specification cannot consider these factors, which may lead to unreasonable design. An analytical algorithm for calculating the overall stability of multi-story shear type braced steel frames. Firstly, the relationship between the brace stiffness and the critical bearing capacity of the structure is analyzed, and the formula for calculating the floor critical braced stiffness is derived; Then, the formula for calculating the critical stiffness ratio coefficient of frame columns under arbitrary supports is derived by using the spring- rocking column mechanical model; Then, the effective lateral stiffness and load stiffness of each floor are assembled between floors, and the solution of the critical bearing capacity of multi-story shear type braced steel frames is converted into the solution of the floor effective lateral stiffness; Finally, based on the weighted average method of axial force, the calculation formula for calculating the critical bearing capacity of the multi-story shear braced steel frame is derived, which can judge the weak story of the structure, quantitatively calculate the mutual support between floors, and effectively make up for the deficiency that the specification cannot solve the effective length coefficient of the columns of the weakly braced steel frame.
Key words
Steel frames /
Shear-type braced /
Floor critical braced stiffness /
Effective lateral stiffness /
Overall stability /
Critical factor /
The critical force;
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