Study On The Lateral Performance Of Steel Braced Frame Based On Sensitivity Analysis

As steel structure building meets the green standards for recycling and reusing,it has a lot of advantages, such as lightweight, high strength, good ductility, good structural performance, construction fast, high degree of industry and so on. With the increase of steel production in China, steel structure building has been developed rapidly, which has been widely used in industrial and civil building.Steel frame structure is a common type of steel structure.Although it has the advantages above, but it also has some disadvantages. Under the rare earthquake, the steel frame structure will be produced larger lateral displacement, causing P-Δ effect obviously.And the carrying capacity and stability of the structure will be taken to the adverse direction. The lateral displacement will be reduced by layouting of brace on the pure frame structure. In the earthquak,a double resistant structure is formed by the braced system and the frame system keeping work together through the floor deformation coordination.It is the first line of defense that the lateral displacement of structure is reduced effectively by bracing.Under the horizontal force, the lateral displacement is a very important parameter in the design of frame support structure. In the engineering project, the steel frame braced is required to has a more accurate lateral displacement calculation formula in the structure design,but there is not more in this area.Firstly,the factors of steel frame support structure has been explored in this paper,which influence on the lateral displacement of structure, such as section of beam column, section of brace section, span of framework, story of framework and so on. Secondly based on the finite element sensitivity analysis and probability design method, sensitivity of factors above and the lateral displacement of the top structure are obtained by establishing APDL parametric modeling. Finally,according to the results of sensitivity analysis, the correlation between those factors and the lateral displacement have been further studied, and then the mathematical model has been established and the constitutive relation of the load and the top lateral displacement have been fit.For the steel frame braced structure model, a series of sustainability framework structure test are designed. Through the test and the finite element analysis, the influence of brace layout on the performance for the overall framework is explored. The main factors are analyzed which influence on the lateral resistant performance among several typical frame braced system.And then the difference between the finite element model and the real model is studied.Finanlly,the new constitutive relations is fit.Compared to the experience formula obtaining from the traditional fitting regression, the method above can analyze accurately the influence of various factors on the top lateral displacement of the frame braced structure.In the result,the new constitutive relationship coefficient parameters have clear physical meaning.The results show that the braced section area and the beam-column section height keep in a dominant position for the lateral stiffness compared to other factors in steel braced frame structure. In the particular model of steel frame braced structure,the beam-column semi-rigid connection is applied in the new fitting lateral displacement formula. The fitting formula is an exponential function, and it is strong plicabilitied that the index has obvious physical meaning.Simultaneously, the fitting formula is understood and applied conveniently in practical engineering.