The Analysis On The Behaviors And Influence Factors Of EK Style Eccentrically Braced Steel Frame In High Buildings

In earthquake-resistance protection zone, especially in the buildings of high earthquake intensity regions, earthquake's action plays the main role generally. It is important to design reasonable structure to meet the needs of bearing capacity and stiffness under frequently occurred earthquakes and energy-dissipation capacity and ductility under rare, extreme earthquakes. These needs bring high standards for lateral resisting system.In traditional moment-resisting steel frames, the beams yield because of bending and form plastic hinges to dissipate energy. Therefore, they possess a part of hysteretic behavior and good ductility. However, their lateral stiffness is not enough. In order to control the structure's deformation, the sections must be larger than what the strength needs. So this kind of system is very uneconomical when it is used in buildings more than thirty floors. If a centrically braced steel frame is used, structure's stiffness can be met easily. However, when the braces buckle under severe earthquake and are out of function, the frame collapses quickly because it can't support these loads, thus its energy-dissipation capacity and ductility is poor. However, eccentrically braced steel frame hybrids the advantages of the two formers and obtains integrated effects of perfect security, applicability and economy when been used in buildings in seismic zone.Eccentrically braced steel frames are seldom used though its design methods are explained in codes of structural design. Some eccentrically braced steel frames are analyzed to offer some reference for farther research and application of EBSF. These analyses are based on the project of ShouGang Group's twelve-floor residences.Single-span and single-floor EBSF is analyzed by the software of SAP2000 with staticand nonlinear method. At first, each frame of the bottom floor and the top floor is analyzed to compare the behaviors of EBSF, triangular CBSF and cross CBSF. Through these compares, more advantages of EBSF than those of the others are illustrated. Secondly, aimed at those factors that may influence the structure's stifihess, bearing capacity, energy-dissipation capacity and ductility, parametric analyses are carried out from eight aspects. These factors consist of section's shape of braces, restraint condition of both ends of braces, ratio of axial compression stress to strength, length of links, slendemess ratio of braces, rigidity per unit length of column, width-to-thickness ratio of flange of links and height-to-thickness ratio of web of links.At last, a few of recommendations and suggestions are put forward for practical design.