Floor mass | m = 18.62 kg | ||
Floor stiffness | k = 4*12EI/L3   = 7.7945 kN/m (L = 400 mm)   = 11.635 kN/m (L = 350 mm) | ||
Mass matrix | \(\left[ {\begin{array}{*{20}c} m & 0 & 0 \\ 0 & m & 0 \\ 0 & 0 & m \\ \end{array} } \right]\) | Stiffness matrix | \(\left[ {\begin{array}{*{20}c} {2k} & { - k} & 0 \\ { - k} & {2k} & { - k} \\ 0 & { - k} & k \\ \end{array} } \right]\) |
Modal parameters | Mode 1 | Mode 2 | Mode 3 |
Natural frequency | |||
 L = 400 | 1.4492 Hz | 4.0605 Hz | 5.8676 Hz |
 L = 350 | 1.7706 Hz | 4.9610 Hz | 7.1689 Hz |
Mode shape normalized to the top floor | 0.4450 | − 1.2467 | 1.8026 |
0.8021 | − 0.5547 | − 2.2474 | |
1.0000 | 1.0000 | 1.0000 |