A novel forced motion apparatus with potential applications in structural engineering

Abstract

This paper reviews the development of forced motion apparatuses (FMAs) and their applications in wind engineering. A kind of FMA has been developed to investigate nonlinear and nonstationary aerodynamic forces considering the coupled effects of multiple degrees of freedom (DOFs). This apparatus can make section models to vibrate in a prescribed displacement defined by a numerical signal in time domain, including stationary and nonstationary movements with time-variant amplitudes and frequencies and even stochastic displacements. A series of validation tests show that the apparatus can re-illustrate various motions with enough precision in 3D coupled states of two linear displacements and one torsional displacement. To meet the requirement of aerodynamic modeling, the flutter derivatives of a box girder section are identified, verifying its accuracy and feasibility by comparing with previously reported results. By simulating the nonstationary vibration with time-variant amplitude, the phenomena of frequency multiplication and memory effects are examined. In addition to studying the aerodynamics of a bluff body under large amplitudes and nonstationary vibrations, some potential applications of the proposed FMA are discussed in vehicle-bridge-wind dynamic analysis, pile-soil interaction, and line-tower coupled vibration aerodynamics in structural engineering.