An equivalent nonlinear beam model for the aeroelastic analysis of shear-type buildings

In this paper, an equivalent one-dimensional beam model immersed in a three-dimensional space is introduced to study the aeroelastic behaviour of tall buildings or towers. The beam is internally constrained, so that it is capable to experience shear strains and torsion only. The elasto-geometric and inertial characteristics of the beam are identified from a discrete model of 3D-frame, via a homogenization process. The model accounts for the torsional effect induced by the rotation of the floors around the tower axis and the nonlinearities generated by the stretch of the columns; the macroscopic shear strain is produced by bending of the columns, accompanied by negligible rotation of the floors. Aerodynamic forces are evaluated through the quasi-static theory, referring to a sectional model under steady wind. Goal of the analysis is to study the critical (galloping) and postcritical behavior of the beam.