Free and forced response of nearly periodic multi-span beams and multi-bay trusses

The influence of several effects on mode localization in free-free multispan beams is investigated. Finite-element methods are used to study localization as a function of Timoshenko beam effects, imperfection strength, coupling strength, and imperfection type. The multispan beam study is conducted with random realizations of a forty-span free-free beam. In addition, free and forced response of free-free trusses and frames is investigated. Results indicate that, for the trusses and frames considered, the dynamic behavior can be approximated by continuum modeling approaches for only the lowest few global modes. Also, for reasonable values of modal damping, localized modes play a subtle role in the overall structural response.