INELASTIC LINK ELEMENT FOR EBF SEISMIC ANALYSIS

A formulation for modeling links in eccentrically braced steel frames (EBFs) subjected to random inelastic cyclic loading is presented. The formulation is plasticity-based, and includes shear and flexural yield ing. In addition, combined isotropic and kinematic shear strain-harden ing effects are accounted for, as well as flexural strain hardening. T he formulation is shown to accurately predict the behavior of test spe cimens involving short links. Inelastic seismic analysis of EBFs with short links was conducted to illustrate the effect of link-modeling as sumptions on EBF response. The analysis results show that link strain hardening can have a pronounced effect on EBF response, leading to lar ger member forces in braces and columns attached to the links. Further more, combined flexural and shear yielding occurred in the links adjac ent to columns, indicating the need to include these types of inelasti c deformations in the link-modeling formulation. Finally, the use in t he analysis of viscous damping in the link was found to cause excessiv e axial forces to develop in braces and columns adjacent to yielded li nks. To reduce this effect, a form of nonproportional viscous damping is illustrated.