When there is no basement in the multi-storey steel structure, can the just-connected exposed column base be used?
Steel Mark" Article 127.Article 1 stipulates: "The column base of the frame column of the multi-high-rise structure can be embedded, the inserted column base and the outer column foot, the multi-layer structure frame column can still use the exposed column foot, the single-storey factory building rigid column foot can use the inserted column foot, the exposed column foot, and the articulated column base should use the exposed column foot." "For steel frames with seismic requirements, the yield mechanism allows the column root to form a plastic hinge, and at this time, the strong nodes (column bases) and weak members (column roots) should be ensured, and the ultimate bearing capacity of the column bases should be checked. Steel Mark, p. 172.Paragraph 4 of Article 9 stipulates that the ultimate bearing capacity of the connection between the column base and the foundation shall be checked according to the following formula.
The above formula puts forward high requirements for the exposed column base, which is difficult to achieve in engineering design. Therefore, the exposed rigid column base is generally used in structures that have no seismic requirements (or no control effect), such as light steel workshops, individual temporary construction, etc.
For multi-layer steel frames in the lower intensity area, in principle, the rigid exposed column base design can be carried out by the performance-based design method. Steel Mark, p. 171.Paragraph 3 of Article 4 requires that when the structural component satisfies the calculation of the combination effect of internal forces with ductility class V, the mechanism control design can be ignored. Combined with Table 17 of the Steel Standard1.3. Table 171.4-2, the ductility grade is V, and the seismic bearing performance level of the plastic performance zone of the standard fortification structural components is performance 3, which should basically meet the performance target of unyielding in large earthquakes.
If the newly connected exposed column base does not meet the design requirements, hinged column feet can also be considered.