Multi-scale computational model for failure analysis of metal frames that includes softening and local buckling

Abstract

In this work we present a new modelling paradigm for computing the complete failure of metal frames by combining the stress-resultant beam model and the shell model. The shell model is used to compute the material parameters that are needed by an inelastic stress-resultant beam model; therefore, we consider here the shell model as the meso-scale model and the beam model as the macro-scale model. The shell model takes into account elastoplasticity with strain-hardening and strain-softening, as well as geometrical nonlinearity (including local buckling of a part of a beam). By using results of the shell model, the stress-resultant inelastic beam model is derived that takes into account elastoplasticity with hardening, as well as softening effects (of material and geometric type) in the fractureprocess zone. The beam softening effects are numerically modelled in a localized failure point by using beam finite element with embedded discontinuity. The original feature of the proposed multi-scale (i.e. shellbeam) computational model is its ability to incorporate both material and geometrical instability contributions into the stress-resultant beam model softening response. Several representative numerical simulations are presented to illustrate a very satisfying performance of the proposed approach.

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

“…The coupling of the computational models can be also weak (e.g. [2,14]). In that case, the shell element is used to compute the failure response of a representative part of each subsystem of a frame under consideration; this information is further incorporated into the beam element that is used for the analysis of the entire frame.…”

“…Inelastic geometrically nonlinear beam finite elements cannot capture automatically those complex effects. However, they can be implicitly included into the beam finite element formulation by using the weak coupling concept suggested in [14] that can be summarized as:…”

Formulación De Elementos Finitos Viga-Columna Con Discontinuidades Embebidas Para Modelar Daño en Elementos Prismáticos De Concreto Reforzado

“…Posteriormente, Armero y Ehrlich (2006) desarrollaron un elemento finito con discontinuidades embebidas con base en la teoría de vigas de Euler-Bernoulli, el cual sólo considera la discontinuidad de rotación. Dujc et al (2010) desarrollaron un modelo multi-escala para el estudio de discontinuidades interiores axiales y rotacionales, en el cual utilizaron elementos sólidos en 2D para la micro-escala y elementos vigas Euler-Bernoulli para la macro-escala. Juárez y Ayala (2012) desarrollaron unas formulaciones para vigas gruesas y delgadas con discontinuidades embebidas con base en funcionales de energía, cuyas aproximaciones con elementos finitos proporcionan matrices simétricas, bien condicionadas, las cuales fueron validadas con ejemplos reportados en la literatura.…”

“…Jukic et al (2013) formularon un elemento finito con discontinuidades interiores basado en la teoría de Euler-Bernoulli que sólo modela la discontinuidad de la rotación. El comportamiento constitutivo del momento contra la curvatura para las vigas de concreto reforzado es semejante al desarrollado por Dujc et al (2010), en el que ocurre ablandamiento posterior al intervalo plástico. Jukic (2013) desarrolló un elemento finito que considera la no-linealidad axial en vigas tipo Euler-Bernoulli y Timoshenko, mediante una sección de viga discretizada en fibras, a las que se les asigna un comportamiento constitutivo esfuerzo-deformación.…”

Concurrent Multi-Scale Modeling of a Transmission Tower Structure and Its Experimental Verification

“…Recently, the concurrent multi-scale method is proposed to model large civil structures [15][16][17], in which the local joints are simulated with shell or plate elements in much detail while other components in the structure are simulated with beam or truss elements. Different scales of elements are then coupled to form a multi-scale FE model.…”