Research On Seismic Behavior Of Semi-rigid Connection Steel Frame Based On Variable Cross-section Braces

High-rise building steel structure mostly uses the frame structure, framestructure mainly includes two kinds: pure steel frame and braced frame. Comparedwith the pure steel frame, in the aspect of structure resisting lateral, braced framehas very obvious advantage.The performance of race and the connections ofbeam-column joints directly influence the performance of the braced frame.According to the stress characteristics of axial forced components, this paperproposes a new semi-rigid steel frame system, which based on the variablecross-section braces. In this dissertation, mechanical analysis and experimentresearch have been carried out to study the hysteresis behavior of variablecross-section braces and the seismic behavior of the braced frame structure system.The main works are listed as follows:(1) In accordance with The Chinese Code for Design of Steel Structures (GB50017-2003) and the laboratory conditions, I have designed and processed12braceswhich have different sizes and shape, experimental tests are carried on them toquasi-static cyclic loads. Observing and recording the experimental phenomena,including the forming and development of buckling deformation, failure position ofbraces, failure mode of braces, etc.(2) Analysis of experimental data, summed up the relationship between thehysteretic behavior of braces with the size of cross section, the shape of crosssection, steel dosage, slenderness ratio, taper.Analyse the experimentaldemonstrations, hysteretic curve, skeleton curve, energy dissipation capability.(3) Find the brace which has the best energy dissipation capability, build finiteelement model of this brace by Ansys, compared the data which calculates byANSYS and the experimental data.(4) The FEM model for two cases of the semi-rigid steel frame based onvariable cross-section braces were created to analyze structural responses under anumber of ground motion records. The time-history of the structural vertexdisplacement, acceleration, interstory drift and base shear were analyzed bycomparing with the steel framework with rigid connections.