Dynamics of Civil Structures, Volume 2: Proceedings of the 39th IMAC, A Conference and Exposition on Structural Dynamics, 2021, the second volume of nine from the Conference brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of the Dynamics of Civil Structures, including papers on:Structural VibrationHumans & StructuresInnovative Measurement for Structural ApplicationsSmart Structures and Automation Modal Identification of Structural SystemsBridges and Novel Vibration AnalysisSensors and Control