Dynamic Characters of Stiffened Composite Conoidal Shell Roofs with Cutouts: Design Aids and Selection Guidelines

Table 5

Clamping options for 0/90/0/90 conoidal shells with central cutouts having 𝑎^′/𝑎 ratio 0.2.

Number of sides to be clamped	Clamped edges	Improvement of frequencies with respect to point supported shells	Marks indicating the efficiencies of number of restraints
0	Corner point supported	—	0
0	Simply supported no edges clamped (SSSS)	Good improvement	35
1	(a) Higher parabolic edge along 𝑥=𝑎 (SSCS)	Marked improvement	46
	(b) Lower parabolic edge along 𝑥=0 (CSSS)	Marked improvement	49
	(c) One straight edge along 𝑦=𝑏 (SSSC)	Marked improvement	52
2	(a) Two alternate edges including the higher and lower parabolic edges 𝑥=0 and 𝑥=𝑎 (CSCS)	Marked improvement	57
	(b) 2 straight edges along 𝑦=0 and 𝑦=𝑏 (SCSC)	Remarkable improvement	88
	(c) Any two edges except for the above option (CSSC, CCSS)	Marked improvement	63
3	3 edges including the two parabolic edges (CSCC, CCCS)	Marked improvement	45
	3 edges excluding the higher parabolic edge along 𝑥=𝑎 (CCSC)	Remarkable improvement	96
4	All sides (CCCC)	Frequency attains the highest value	100