Simulating the Inelastic Seismic Behavior of Steel Braced Frames Including the Effects of Low-Cycle Fatigue

摘要

The report describes simulations of the inelastic seismic behavior of steel braced frames including the effects of low-cycle fatigue. Various types of nonlinear behavior are considered: material inelasticity, low-cycle fatigue, and local and global geometric nonlinearities. The effects of suddenly started, quasi-brittle fracture are not considered herein. For steel braced frames, braces, columns, beams, and connections subjected to significant axial loads and deformations, as well as bending moments and shear. Under these complex-loading conditions, a wide variety of behavior mechanisms and failure modes may occur for each type of member and connection. Thus, numerical models that assess the initiation and propagation of failure during cyclic loading need to account for multi-axial states of material nonlinearity, local and global buckling, and the exhaustion of the ability of the material to deform inelastically caused by low-cycle fatigue. Following a review of existing material models for simulating structural steel deterioration, a series of investigations are conducted using finite element modeling techniques. Finite element methods can directly account for complex states of stress and changes in deformed shape.