Section 3 Panel scantling requirements – decks loaded by wheeled vehicles

3.1 Application

3.1.1 The requirements of this Section cover decks loaded by wheeled vehicles and are in addition to the requirements in Pt 3, Ch 9, 3 Decks loaded by wheeled vehicles of the Rules and Regulations for the Classification of Ships, July 2022 with the exception of;

3.2 Decks loaded by wheeled vehicles

3.2.1 The scantlings of vehicle deck panels are to satisfy the most severe arrangement of print wheel loads.

3.2.2 The deck plate thickness is to be not less than:

t ₁

t _n1 + t _a1

t ₂

t _n2 + t _a2

where

t _a1, t _a2	=	1,5 mm for strength deck, weather decks, decks forming crown of tank, inner bottom
t _a1, t _a2	=	1,0 mm for internal decks elsewhere.

The thicknesses t _n1, t _n2 are to be selected so that the criteria in Ch 3, 3.2 Decks loaded by wheeled vehicles 3.2.4 are satsfied.

3.2.3 The bending stress, σ_b, in the panel subjected to wheeled vehicles is to be taken as:

where

φ	=	where the wheel load is assumed to be adjacent to the girder, see Figure 3.3.1 Diagrammatic illustration of wheel load location and size
φ	=	1,0, where the wheel load is assumed to be on the centre of the panel, see Figure 3.3.1 Diagrammatic illustration of wheel load location and size

width of the wheel load, see Figure 3.3.1 Diagrammatic illustration of wheel load location and size

P ₁	=	corrected patch load, in N
P ₁	=	9806 P _w λ

P _w

load, in tonnes, on the tyre print. For closely spaced wheels the tyre print area may be taken as a combined print area, see also Ch 3, 3.2 Decks loaded by wheeled vehicles 3.2.4

λ	=	dynamic magnification factor
	=	1,25 for harbour conditions
	=	(1 + a_zn) for sea-going conditions

a_z

is the vertical acceleration at the location under consideration, see Pt 3, Ch 9, 9.2 Loading 9.2.3 of the Rules and Regulations for the Classification of Ships, July 2022

tyre correction factor, see Table 3.3.1 Tyre correction factor, n

breadth of panel in the transverse direction

length of panel in the longitudinal direction

the smaller of w or l

t _n-av	=	average net thickness
t _n-av	=

Coefficients C ₁ to C ₉ are to be obtained from Table 3.3.2 Curvature factor coefficients truck wheel loads or Table 3.3.3 Curvature factor coefficients car wheel loads for truck wheel loads and car wheel loads respectively.

Figure 3.3.1 Diagrammatic illustration of wheel load location and size

Note The details shown in this figure are for illustration purposes only

Table 3.3.1 Tyre correction factor, n

Number of wheels in idealised patch	Pneumatic tyres	Solid rubber tyres	Steel or solid tyres
1	0,6	0,8	1,0
2 or more	0,75	0,9	1,0

Table 3.3.2 Curvature factor coefficients truck wheel loads

Aspect Ratio, w/l	Short span, s, mm	t _n1, t _n2 mm	Coefficients
			C ₁	C ₂	C ₃	C ₄	C ₅	C ₆	C ₇	C ₈	C ₉
Single axle configuration, wheel load at center
w/l > 1,0	2000 ≤ s ≤ 2500	3	0,3	–0,2	8	150	0,04	–80	–35	130	–95
	2000 ≤ s ≤ 3000	4,5
	2000 ≤ s ≤ 3500	6,8,10	0,3	–0,2	8	150	0,04	–80	–35	130	–95
0,5 ≤ w/l ≤ 1,0	2000 ≤ s ≤ 2500	3	0,3	–0,2	8	150	0,04	–80	–	–	–
	2000 ≤ s ≤ 3000	4,5
	2000 ≤ s ≤ 3500	6,8,10	0,3	–0,2	8	150	0,04	–80	–	–	–
Double axle configuration, wheel load at center
w/l > 1,0	s = 2500	4	0	1,6	22	100	0,04	–100	–35	130	–95
	2500 ≤ s ≤ 3000	5
	2500 ≤ s ≤ 3500	6	0,3	0,4	8	180	0,04	–115	–45	165	–120
	2500 ≤ s ≤ 3500	8
	3000 ≤ s ≤ 3500	10
0,5 ≤ w/l ≤ 1,0	s = 2500	4	0	1,6	22	100	0,04	–100	–	–	–
	2500 ≤ s ≤ 3000	5
	2500 ≤ s ≤ 3500	6	0,3	0,4	8	180	0,04	–115	–	–	–
	2500 ≤ s ≤ 3500	8
	3000 ≤ s ≤ 3500	10
Double axle configuration, wheel load adjacent to transverse girder
w/l > 1,0	s = 2000	3	0,8	–1,5	5	140	0,06	–120	–35	130	–95
	2000 ≤ s ≤ 2500	4
	2000 ≤ s ≤ 3000	5
	2000 ≤ s ≤ 3500	6	0,6	–0,3	–3	230	0,045	–130	–40	150	–110
	2500 ≤ s ≤ 3500	8
	3000 ≤ s ≤ 3500	10
0,8 ≤ w/l ≤ 1,0 use w/l = 0,8 if 0,5 ≤ w/l ≤ 0,8)	s = 2000	3	0,8	–1,5	5	140	0,06	–120	0	–50	50
	2000 ≤ s ≤ 2500	4
	2000 ≤ s ≤ 3000	5
	2000 ≤ s ≤ 3500	6	0,6	–0,3	–3	230	0,045	–130	0	–50	50
	2500 ≤ s ≤ 3500	8
	3000 ≤ s ≤ 3500	10

Table 3.3.3 Curvature factor coefficients car wheel loads

Aspect Ratio, w/l	Short span, s, mm	t _n1, t _n2 mm	Coefficients
Aspect Ratio, w/l	Short span, s, mm	t _n1, t _n2 mm	C ₁	C ₂	C ₃	C ₄	C ₅	C ₆	C ₇	C ₈	C ₉
Single axle configuration, wheel load at center
w/l > 1,0	2000 ≤ s ≤ 3000	3,4	0,2	0,4	25	200	0,04	–80	–50	185	–135
0,5 ≤ w/l ≤ 1,0	2000 ≤ s ≤ 3000	3,4	0,2	0,4	25	200	0,04	–80	–	–	–

3.2.4 The bending stress, σ_b, in Ch 3, 3.2 Decks loaded by wheeled vehicles 3.2.3 is to be less than , where fσ is the structural design factor which is to be taken as 0,525.

3.2.5 Where decks are designed for the carriage of wheeled vehicles only or where the panels are subjected to a distributed load in addition to the vehicle loading, the scantling requirements are to be specially considered on the basis of direct calculation. The load area is defined as the footprint of an individual wheel or the area enclosing a group of wheels when the distance between footprints is less than the smaller dimension of the individual prints. The structural design factor, fσ, is to be as required by Pt 3, Ch 9 Special Features, Table 9.3.6 Structural design factors of the .

3.2.6 The vehicles are to be positioned so as to produce the most severe loading condition for each panel under consideration.