The Research On Stability Coefficient Of Steel Frame Structures Considering P-△ Effects

The design of steel frame structures is performed conventionally using first-orderelastic analysis to obtain the displacement and the internal force. Too manyassumptions results in more and more challenges. P-Δeffect is one of the mostimportant factors in steel frame structures especially in multi-story and high-rise steelframe structures. Codes of many countries aiming at whether considering the P-Δeffects or not and how to consider the P-Δeffects are different in a certain extent. InChinese Code for design of steel structures, a second-order simplified method toconsider P-Δeffects using the amplified parameter is put forward. In itscommentary, some examples are analyzed. And as a result the rational applicationextent is gained. The stability coefficient is the most important parametersconsidering P-Δeffects. So the research on this parameter has academic andpractical significance.After looking back the state-of-the-art of the geometry nonlinear characteristic ofsteel frame structures home and abroad, this paper introduces the definition ofstability coefficient. Several stability coefficients in different countries'codes arecompared subsequently. At the same time, the nonlinear finite element methodconsidering P-Δeffects, the approximate methods and methods recommended bycodes in several countries are introduced. On the basis of discussing the significationof stability coefficient, analysis of stability coefficient is done in cantilever structuresusing the current finite element program SAP. The errors of displacement in methodsamong one-order analysis, amplified parameter simplification second-order methodand accurate method are compared under the given value of stability coefficient. Letthe values of stability coefficient of one-bay-one-story frame, one-bay-two-storyframe, one-bay-three-story frame and two-bay-six-story frame equal to 0.10, 0.25 and0.30 respectively through changing the loads on these frames. The errors ofcalculating lateral displacement, peak displacement and internal force among thethree methods are compared subsequently. At the same time, the validation of theextent of stability coefficient is also done. Finally, many examples (including threemulti-story and high-rise steel frame structures in real-life) forming through changingsome parameters which affecting stability coefficient are analyzed. The correspondingrelations between the errors of lateral displacement and stability coefficient aresummarized. Some discussions are performed to obtain the rational extent of stability...