Study On Seismic Design Method Based On P-Δ Effects Of Steel Frame

In recent years, crustal movement come into the active phase.Earthquake has becomethe biggest disasters to human life and property. Improve the seismic performance ofbuildings has become research focus and hotspot. Steel frame structure has a good seismicperformance, but structure stiffness is flexible. Second-order effects become one of themost important factors of structure seismic performance. In engineering design, includingsecond-order effect design method is a currently hot research.In this paper, the following points will be studied: First summarizes the studies aboutsecond-order effects; the relationship between steel frame stability demand andclassification of elastic stability will be studied; the effect of structural defects andcomponent defects on steel frame lateral stiffness; the elastic-plastic lateral stiffness factors;according to the calculation results, consider the second-order effect given the seismicdesign recommendations.Currently,"Code for seismic design of buildings" and "Code for design of steelstructures" considering second order effects by elastic stability. The steel frame is designedaccording to the above suggestions, the physical concept is not clear. Summary the latestresearch about steel frame seismic performance consider second-order effects. This papersummarizes the current domestic and foreign seismic design method, then providefoundation for this study.According to the concept of load negative stiffness, pointed out the nature of steelframe elastic stability. Give the relationship between steel frame stiffness that earthquakedemand for and elastic stability classification.Analyse the coefficient function betweensteel frame structural stiffness requirement and calculation length. Study concludes that the steel frame structure in high-intensity seismic area stiffness requirement is greater thanload negative stiffness. Finally, according to results of the analysis and the current designmethod, the design recommendations are given.The initial defects of mainly includes structure steel frame structure: structure initialdisplacement, member initial curvature, residual stress. The geometry of P-Δ effect is oneof steel frame stable factors.Take Vogel frame calculation results as the finite elementanalysis parameters correction foundation. Analyse different parameters steel frame,including the different axial compression ratio, different layers, different cross-section steelcolukNs and different slenderness ratio.Induction influence of different initial defects andstudy displacement plastic state of steel frame under lateral seismic loads. The initialdefects and geometric large deformation has has little effect on steel frame lateral bearingcapacity in addition to residual stress.Based on a large number of numerical analysis, summarize factors of steel frameelastic lateral stiffness and stability coefficient. Study concludes that the main factor is theaxial compression ratio of the steel colukNs, with the axial compression ratio increases, thelateral stiffness decreases; main factor is the material nonlinearity. At the same time studyconcluded that beam end restraint stiffness on elastic-plastic lateral stiffness influence issmall; with steel colukN slenderness ratio decreases, the extremes of elastic stabilitycoefficient decreases.Finally, in summarizing the results of numerical analysis, the design countermeasuresand suggestions considering the two order effects is given. According to the seismic forceto fix steel frame calculation length coefficient method is recommended; Compared withthe structure stability coefficient, story axial compression ratio that control structureelastic-plastic lateral stiffness is more reasonable index; and gives the braced framestructures shear distribution design recommendations; The way that advanced analysis isused for steel frame seismic design is reasonable, but also gives load models andassessment methods.