Concentrated plasticity-based second order formulation for analysis of semirigid steel-concrete composite frames and beams with partial shear connection

Resumo

The present work aims at the implementation and validation of a displacement-based two-dimensional
numerical formulation including several sources of non-linearities in steel-concrete composite frames, such as:
second order effects; plasticity; beam-to-column semi-rigid connections; and partial shear connection on beams.
The finite element method is used together with the co-rotational approach in order to allow large displacements
and rotations in the numerical model. The degradation of axial and flexural stiffness is determined exclusively at
the nodal points of the finite element mesh, characterizing the concentrated plasticity. In cross sections, the Strain
Compatibility Method (SCM) is used to capture the axial strains in the components of the section and also the
slip in the steel-concrete interface. Sliding is considered by introducing a degree of freedom at the steel-concrete
interface in the analysis of the cross section. In this way, the constitutive models of the materials and the shear
connection elements are described by continuous functions. The semi-rigid connections are simulated by means
of zero-length pseudo springs that are introduced at the finite elements ends, making them hybrid. To validate the
proposed numerical formulation, the results obtained are compared with numerical and experimental data available
in the literature. Since the model proposed here starts from the concentrated simulation of nonlinear effects, a study
of the finite element mesh refinement is also carried out.