Weak coupling of shell and beam computational models for failure analysis of steel frames

• A concept for analysis of steel frames, which couples shell and beam models, has been studied.
• The resulting steel frame analysis takes into account local buckling and localized material failure.
• The concept has large potential for practical applications.

A hierarchical modeling of planar steel frames that is based on a weak coupling of shell and beam computational models is studied in detail. A shell finite element is used to compute failure response of a representative part of each column and each beam of a frame under consideration; elasto-plasticity, geometrical nonlinearity and material softening (along with a localization limiter) are taken into account. The computed results, which naturally include local buckling and/or localized material failure effects, are further incorporated into a beam inelastic stress-resultant constitutive model; the embedded-discontinuity-in-rotation Euler–Bernoulli finite element is considered in this work. The designed beam finite element formulation can be effectively used for the failure analysis of the steel frame. Important issues of such weak coupling concept are presented and results of several numerical simulations are discussed.