Iranian Classification Society Rules

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Section 2 Longitudinal Framing System

201. General

1. General

Other than specified this Chapter, relevant rules of Sec 1.

2. Application

The requirements of this Chapter pontoon type dredgers

the longitudinal framing system is to be in compliance with the

are generally to applying to the longitudinal framing system of

Ch 5

202. Construction and scantlings

1. Structural arrangement

(1) In the ship's centerline, longitudinal bulkhead is to be provided or special consideration is to be taken to have equivalent strength.

(2) Bottom transverse, side transverse and deck transverse are to be arranged at an interval of 3.5

m or less.

(3) The standard spacing of longitudinal beam, bottom and side frame is obtained from the follow-

ing formula.

2 Ä + 550 (mm )

(4) When flat bars are used for longitudinal beams, the ratio of depth and thickness is not to be exceeded 15.

2. Solid floor

In the longitudinal framing system of double bottom construction, the thickness of solid floor is not to be less than that obtained from following formula.

ŊĦĒĬJÄ Ğ ËĦÈ (mm)

3. Bracket

(1) In the longitudinal framing system of double bottom construction, the brackets connected to ad- jacent bottom longitudinal are to be provided at an interval not exceeding 1.75 m on the center girder between the solid floors and connected to center girder, shell plating and bottom longitudinals.

(2) In the longitudinal framing system of double bottom construction, the brackets extending from the margin plate to adjacent bottom and inner bottom longitudinals are to be provided at every hold frame and connected to margin plate, shell plate and longitudinal frames etc.

(3) The thickness of bracket mentioned above is not to be less than that obtained from the follow- ing formula. However, it does not need to exceed the thickness of solid floor.

ŊĦÈĬJÄ ĞËĦÈ (mm )

(4) The thickness of stiffeners required by (1) is to be same as that of plating and the depth of stiffener is not to be less than 0.08 ẀŊ (m ) of plat bar or equivalents. Where ẀŊ is the depth of center girder.

4. Bottom longitudinal and inner bottom longitudinal

(1) The section modulus of bottom longitudinals is not to be less than that obtained from the fol- lowing formula.

ŊĦÈÅǼŶË (cmĖ )

Å : Space of longitudinal (m )

Ŷ : Distance between supports (m )

(2) In the longitudinal framing system of double bottom construction, the section modulus of inner

bottom longitudinals is not to be less than 85 % of inner bottom longitudinals in the lower part of deep of Ch 7, 302.

5. Strut

(1) When the distance between floors is exceeded 2.5 m ,

section modulus obtained from (1). And tank which is not arranged strut is to be

the strut is to be installed at the midpoint

between floors. The strut is to be of rolled sections other than flat bars or bulb plates and to

Ch 5

be well overlapped with web plating of bottom and inner bottom longitudinal.

(2) The sectional area of strut of Par 1 is not to be less than that obtained from the following formula.

ËĦËÅ ẄY (cmĖ)

Å : space of floor (m )

Ẅ : breadth of area supported by strut (m )

Y : Vertical distance from the longitudinals to a point of Ẁ Ğ ŊĦŊËÈ Ä above the top of keel (m)

6. Bottom transverse

The scantling of bottom transverse is not to be less than that obtained from the following formula.

Section modulus : ĒĦĖÅǼŶË (cmĖ), thickness of web : 10 Ẁ + 1.5 (mm )

Å : space of transverse (m )

Ŷ : length between supports by transverse (m )

ẀŊ : depth of web (m )

7. Thickness of inner bottom plating

The thickness of inner bottom plating is not to be less than that obtained from the following formula.

ĖĦĒÅĬJẀ Ğ ËĦÈ (mm )

Å : space of inner bottom longitudinals (m )

8. Bottom longitudinal

(1) The section modulus of bottom longitudinals is to comply with followings.

(A) The section modulus of longitudinal in the midship part is not to be less than that obtained from the following formula.

ŊĦÈÅYŶË (cm Ė)

Å : space of longitudinals (m )

Ŷ : length between supports of longitudinal (m )

Y : vertical distance from the position of each longitudinal to the point of Ǽ above the keel plate. However, when h is less than ŊĦĖĬJÄ (m ), Y is to be taken as ŊĦĖĬJÄ (m ).

(B) The section modulus of longitudinals in the forward and aft part other than midship part

may be gradually reduced (A). However, the section collision bulkhead is not to

and it may be of 85 % of that obtained from the formula of modulus of longitudinals between 0.15 Ä from fore end and the

be less than that obtained from the formula of (A).

(2) The ratio of depth to thickness is not to be exceeded to longitudinals.

(3) The slenderness ratio of longitudinals attached to sheer srake

ceeded 60.

9. Side transverse

(1) The scantling of side transverse is not to be less than

15 when flat bars are used for

in midship part is not to be ex-

that obtained from the following

Ch 5

formula.

Section modulus : ĒÅYŶË (cmĖ ), thickness of web : 10 Ẁ + 1.5 (mm )

Å : space of side transverse (m )

Ŷ : distance between supports of transverse (m )

Y : vertical distance from midpoint of Ŷ to Ǽ on the keel plate

However, Y is less than ŊĦĖĬJÄ ẀŊ : depth of web (m )

(2) The side transverses are to be provided

(m ), h is to be taken as ŊĦĖĬJÄ (m ).

with tripping brackets at an interval of about 3 m or

the webs are to be strengthened by fitting the stiffeners where longitudinals are penetrated.

However, a stiffener can be provided at every longitudinal in the middle part of side transverses.

10. Longitudinal beams

(1) The section modulus of longitudinal beams in the midship part is not to be less than that ob- tained from the following formula.

ËĦËĖ ÅYŶË (cm Ė)

Å : space of longitudinal (m )

Ŷ : length between supports of longitudinal beam (m )

Y : specified in the requirements of Ch 4, 202. 1

(2) The section modulus of longitudinals installed in forward and aftward of midship part can be gradually reduced. However, it is not to be less than that obtained from the following formula.

ŊĦĖĖ ÅYŶË (cm Ė)

Å, Y and Ŷ : specified in (1)

11. Deck transverses

The scantling of deck transverses is not to be less than that obtained from the following formula.

Section modulus : ŊĦĖĒĖ ÅYŶË (cmĖ ), thickness of web : 10 Ẁ + 1.5 (mm )

Å : space of deck transverse (m )

Ŷ : length between supports of deck transverse (m )

Y : specified in Ch 4, 202. 1

ẀŊ : depth of web (m )

203. Fore and aft construction

1. General

(1) Bottom and side transverses supporting bottom and side longitudinal frames are to be arranged at an interval of about 2.5 m , and supported by side girders and side longitudinal girders or cross tie which are arranged at an interval of about 4.6 m . And side transverses are to be ef- fectively connected with bottom transverses.

2. Longitudinals in fore peak tank

The section modulus of longitudinals below the upper deck in the forward of collision bulkhead are

Ch 5

not to be less than that obtained from the following formula. However, it is not to be less than 30 cm Ė.

ĒÅYŶË (cmĖ)

Å and Ŷ : complying with 202. 8 (1) of Rules.

Ŷ : vertical distance from the frame to 0.12 Ä above the keel plate.

However, Ŷ is less than 0.06 Ä (m ), Ŷ is to be taken as 0.06 Ä (m )

3. Construction forward the collision bulkhead

(1) The scantlings of bottom transverse supported at ship centerline are not to be less than that ob- tained from the following formula.

depth of transverse : 0.2 Ŷ (m ) and 0.0085 Ä + 0.18 (m ), whichever is the greater section modulus of transverse : ËĦËÅÄŶË (cmĖ)

ÅÄŶ

thickness of web : ŊĦŊŊÈ JẀË

Ğ ËĦÈ (mm ) and ŊĦÈĬJÄ Ğ Ė (mm ), whichever is the greater.

S : space of transverse (m )

l : length between supports by transverse (m )

d1 : value which is the depth of transverse deducted depth of slot (m )

(2) The scantling of center girder is not to be less than that specified (1).

(3) The scantling of side transverse supporting longitudinal frames is not to be less than that ob- tained from the following formula.

Depth of transverse : 0.2 ŶŊ (m ) and 2.5 times of the depth of slot for longitudinal frame penetration, whichever is the greater. However, it is not to be less

than that obtained the following formula.

Ä < 90 m : 0.0053 Ä + 0.25 (m ), Ä ≧ 90 m : 0.0025 Ä + 0.5 (m )

Section modulus of transverse : ĒÅYŶ Ë (cm Ė)

ÅYŶŊ

Thickness of web : ŊĦŊĖËJẀË

greater.

Ğ ËĦÈ (mm ) and 0.02 Ä + 5.5 (mm ), whichever is the

: space of transverse (m )

: complying with rules of Par 1.

h : vertical distance from midpoint of

to the point 0.12 Ä above keel plate (m ).

However, h is less than 0.06 Ä, h is to be taken as 0.06 Ä.

: unsupported length of side transverse (m )

(4) Where the lontgitudinal is penetrating the side stringer, the side transverse is to be strengthened by fitting stiffeners.

(5) The scantling of side stringer supporting side transverse is to be greater than that obtained

from the following formula.

Depth of stringer : 0.2 ÂË (m ) and the value obtained from the following formula, whichever is the greater

Ch 5

Ä < 90 m : 0.0053 Ä + 0.25 (m ), Ä ≧ 90 m : 0.0025 Ä + 0.5 (m )

Section modulus of stringer : ĖÅYŶŊŶË (cm )

ÅYŶË

web thickness : ŊĦŊĖË JẀË

Ğ ËĦÈ (mm ) and 0.02 Ä + 5.5 (mm ), whichever is greater

Å : space of side stringer (m )

h : vertical distance from the center of

S to 0.12 Ä on the keel plate (m )

l0 l1 d

However, the distance is less than 0.06 Ä (m ), it is to be of 0.06 Ä (m )

: distance between supports of side transverse (m )

(6) The

sectional area of cross tie supporting side transverse is not to be less than that

obtained

from the following formula.

In case, l/k is greater than 0.6 :

ŊĦĒĒÅẄY ËJGŊĦÈFŶĤÝF

(cm Ė)

In case, l/k is less than 0.6

: ËĦËÅẄY (cmĖ )

Å : space of side stringer (m )

h : vertical distance from the center of Å to 0.12 Ä above the keel plate (m )

However, h

is less than 0.06 Ä (m ), h is to be taken as 0.06 Ä (m )

l : depth of cross tie (m )

JÂ

Ý G ĬJA

: Minimum moment of inertia of cross tie (cmĖ)

: sectional area of cross tie (cmË)

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