Nonlinear Resonance Analysis of Slender Portal Frames under Base Excitation

Table 1

Four first natural frequencies of the pitched-roof frame.

(m)	Natural vibration frequency (rad/s)
	1st mode	2nd mode	3rd mode	4th mode
0.0	21.82	48.97	130.54	161
3.0	19.61	47.14	108.23	159.80
6.0	15.40	36.42	83.21	92.08