Collapse Mechanism And Design Criteria Of Eccentrically Braced Steel Frames Under Cyclic Load

Eccentrically braced steel frames are a lateral load-resisting system which apply high intensity area and it can provide the high elastic stiffness that met higher steel building drift requirement. The links of Eccentrically braced steel frames sustain large inelastic deformation without loss of strength under severe earthquake loading which demonstrate excellent energy-dissipation capacity and ductility. It was tested and theories studied by many scholars at home and broad, and as a result, the achievements have been applied engineering practice. This p aper aim at the project application, study on collapse mechanism and design criteria of eccentrically braced steel frames under cyclic Load.A new nonlinear finite element model which applies subsystem connect beams element and space degenerate shell element to analyze eccentric braced structural energy-dissipation and links collapse mechanism is presented in this paper. In the process of finite element analyzing, the beam, column and b race that not enter the plastic parts adopt bearn element that considered geometry nonlinear. The links entering plastic adopt space degenerate shell element that considered the nonlinear large-deformation, together with mixed hardening rule, which linearly combines isotropic and kinematic hardening. The method applied two elements to analyze the collapse mechanism and hysteretic behavior of eccentrically braced steel frames under cyclic Load in structure at first time. Computer program BSNFEM is complied. Good agreement is found between the theoretical predications and experiment result.This paper applies nonlinear finite element program BSNFEM to analyze the behaviors of eccentrically braced steel frames under cyclic load. The study that comprehensive and systematic analyze the factor of links length, thickness of links flange, distance of links rib, thickness of links rib and angle of brace to be changed affect energy-dissipation capacity of D shape and K shape eccentrically braced steel frames have been some studied before. This paper fills the black in the filed factor of high-span ratio, brace stiffness and brace-to-beam connections to be changed affectenergy-dissipation capacity of D shape and K shape eccentrically braced steel trames and any factor to be changed affect energy-dissipation capacity of Y shape eccentrically braced steel frames.Suggestions for seismic design based on FEM analysis are presented at last. The study that analyzing three kind of eccentrically braced steel frames is rather comprehensive and systematic, and the conclusions can be useful for revising design code, guiding design of engineering, and provide good basis for further to study seismic-resistant behavior of eccentrically braced steel frames.