Control Method of the Stability of Frame Structures by Its Ratio of Rigidity-to-Gravity Considering the Influence of the Ratio of Axial Compressive Force to the Axial Compressive Ultimate Capacity of Section

Experiments in compression and bending were done for 10 concrete columns and 5 steel columns with various ratios of axial compressive force to the axial compressive ultimate capacity of the section,and the influence formulae of the ratio of axial compressive force to the axial compressive ultimate capacity of the section on the sideway stiffness of the frame columns were drawn out.The critical gravity load of the structure was derived by the equivalent horizontal load method,and the calculation method about the stability of the frames,which considered the effect of the second order of gravity by controlling the ratio of rigidity-to-gravity of the structure,was presented.It has been shown that the sideway stiffness of the frame columns increased when considering the influence of the axial load on the sideway stiffness of the frame columns,which made the ratio of rigidity-to-gravity meet the demand of the stability of the frame structures.Taking into account the influence of the axial load on the sideway stiffness of the frame columns can agree with engineering practice and can be helpful to the revision of the existing design codes for calculating the sideways of frames.