BEHAVIOR OF HIGH AND INTERMEDIATE FREQUENCY MODESOF STRUCTURES SUBJECTED TO HARMONIC EXCITATION

摘要

Abstract. Dynamic analysis of structures subjected to harmonic and seismicloads shows that the contributions of high frequency modes are essentially static.The modal responses of the structures subjected to harmonic excitation aregenerally combined using square root of sum of squares (SRSS) rule for wellseparated modes. The combination of modal response s using SRSS will resultsin erroneous results for even well separated modes, if the high frequency modeshaving frequency greater than operating frequency are included. This papermakes an attempt to identify the behavior of the modes which have a frequencygreater than the operating frequency. The rigid and periodic part of the responseare assumed to be statically independent and the behavior of high frequency andintermediate frequency modes of structures subjected to harmonic loads arestudied with the help of an example. The problems involved in using the avail-able modal combination rules in combining the modal responses, when highand intermediate frequency modes are included are discussed.