Analysis On Earthquake-resistant Performance Of Knee Braced Steel Frames

Knee braced frame (KBF) is a new braced structure style. The feature of KBF is one of the knee ends connects to the beam, the other one connects to the column, and not less than one end of the brace connects to the knee. The knee in the braced system is designed as a dissipating member, so it can dissipate energy by plastic distortion and yield in shear in advance to avoid the main members destroyed under infrequency earthquake. KBF combines the stiffness of the concentrically braced frame (CBF) and the inelastic behavior of moment- resistant frame (MRF), and overcomes the disadvantage of the eccentrically braced frame (EBF) dissipating energy by immolating the main member. So it is an effective lateral load-resisting braced structure style which can apply in high intensity area. The series researches have been developing abroad, but the theories of KBF have not been carried out. The researches at home are just begun. As the aseismic fortification is required in most area in China, in order to utilize the advantage of the KBF and explore the application of KBF, the researches on the aseismic performances of the KBF are not only significant in theory, but also important m practice.Knee elements are elements dissipating energy in knee-brace-frames and their design parameters have great influence on the earthquake-resistant performance of knee-brace-frames. The paper investigates the influence of the knee element on the earthquake-resistant performance of steel knee-brace-frame by finite element analysis. At last, energy-dissipation of the KBF has been analyzed with the finite element menthol . The analysis indicated that the knee element yielded firstly and insure that the main members did not fail and enhance the enemy-dissipation and defamation capability of the structure .