Preliminary Assessment of Biaxial Bending Effects on the Deformation Capacity of Steel Tubular Members

The investigation of the response of steel structures to seismic loads has been extensively studied in recent decades. While the monotonic behaviour of steel members subjected to uniaxial bending is well understood, the cyclic behaviour characterization, particularly for steel components under biaxial bending, needs further research. This is of utmost importance for the seismic assessment and performance evaluation of steel buildings as the adoption of modelling and damage assessment criteria established for members subjected to uniaxial bending may not be fully appropriate for the seismic analysis of buildings comprised of structural steel tubular members. This work aims to characterize the behaviour of steel columns subjected to biaxial cyclic bending and to compare it with the behaviour under uniaxial loading conditions. Detailed 3D finite element analyses are conduced to study the effects of bidirectional lateral cyclic loading on the hysteretic response of steel columns with circular, square, and rectangular sections, and under different uniaxial and biaxial lateral displacement-controlled load paths. The numerical findings indicate that biaxial cyclic loading paths can play a relevant influence on the rotation capacity, ductility, and energy dissipation capacity of steel tubular members.