Periods and vibration modes for common RC frame structures

A theoretical method allowing determination of vibration modes for RC frame structures with identical floors, or with either the first or the last floor differing from other floors, is proposed in the paper. As a result of the research, all natural vibration modes for buildings with two to ten identical storeys are presented in a table. These results can be extended to include a greater number of floors (more than ten). A mathematical method for determining characteristic polynomial coefficients of a specific tridiagonal matrix is also proposed.