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Hull and Outfitting

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PATTERN Statement

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  • Last UpdatedDec 02, 2025
  • 4 minute read

The PATTERN statement specifies rules for the selection of a certain profile pattern on a bracket. In general it is supposed that the depth of the bracket perpendicular to the free side of the bracket (Z in the figure below) is a controlling parameter for the position of the stiffeners and that the dimensions of the profiles are depending on certain lengths and on the thickness of the bracket.

These lengths are (see the figure below for explanation):

  1. Length of the free side of the bracket when extended to the surrounding restricting structural elements (=L0).

  2. The actual length of the stiffeners (L1, L2, L3, ...)

    Figure 5:15. Lengths for calculation of profile sizes.

It is supposed that maximum 5 stiffener positions need be considered in a bracket. In a pattern for a welded flange (face plate) only one profile may be generated. All the stiffeners must be parallel to each other.

If a bracket contains both a face plate and stiffeners separate patterns must be used for the face plate and the stiffeners.

Syntax:

PATTERN,

< pattern_name >
/ NO_STI = < N >
[ / DOUBLE ]
/ LOCATION = (<loc1>, ..... , <locN>)
/ SIZE_FACTOR = (<fact1>, ..... ,<factN>)
/ LENGTH_NO = (<No1>, ..... , <NoN>)
/ RULE = < rule_No >
;

< pattern_name>

A name (string not longer than eight (8) characters) that uniquely identifies a certain stiffener pattern specification.

NO_STI

Number of stiffener positions in this pattern. Should be 1 for face plate.

This attribute must be given before any of those where the number of arguments are depending on < N >.

DOUBLE

Means that the first stiffener should be doubled, that means, one stiffener on each side. Both stiffeners should be equal and the given factor should be shared half for each of them.

LOCATION

Specifies the distance of the stiffeners from the free edge (or possibly part of it, for example, an arc, cf. below), with one specification for each stiffener position. Should be 0 for a face plate.

Suppose that the depth of the bracket perpendicular to the free side is Z. The position is always given as a distance from the free edge (or a specified part of it).

<loc> >1 means that the distance is given explicitly,

<loc> <1 means that the distance is given as a factor.

<loc1> is used for stiffener position 1, <loc2> for stiffener position 2,

SIZE_FACTOR

Specifies a factor that shall be used for the calculation of the profile dimensions. <fact1> is used for the stiffener in position 1, One size factor shall be given for each of the stiffeners of the given pattern. for further information, see below.

LENGTH_NO

Specifies the length that shall be used in the evaluation of the dimension of each of the profiles:

= 0 means L0,

= 1 means L1,

RULE

Specifies how the cross-section area shall be evaluated (cf. below). Normally the profile cross section area should be compared to the area of the selected length (L0, L1, , cf. above) multiplied by the thickness of the bracket and divided by 10. (The rules specified below will always be overruled if the user controls the profile dimensions by input.)

> 0:

= 1 Pick profile with closest to cross-section area.

= 2 Ditto closest but smaller.

= 3 Ditto closest but larger.

< 0:

In this case the dimensions are not calculated automatically but a fixed profile is picked from the currently used profile set. Abs (RULE) is the index within this profile definition set for the profile to be picked.

Normally, the profile is should be set parallel to the longest straight line in the free side of the bracket. However, in certain cases it may be necessary to set the stiffener parallel to part of the free side according to another rule. Then the following rules apply:

  • Adding 100 (with the same sign as RULE as per above) means that the stiffener(s) will be set parallel to the tangent of the mid-point of the largest circular arc of the free side (to be used for example, for a bracket where the free side consists of one arc).

  • Adding 200 means that the stiffener will be located parallel to the last segment preceding the largest arc (cf. adding 100).

• Adding 300 means that the stiffener will be located parallel to the first line segment following the largest arc (cf. adding 100).

These cases are illustrated in the figures below.

Figure 5:16. Options for positioning of bracket stiffener.

Suppose that stiffener 2 shall be calculated and the following values have been assigned:

RULE

=1

<loc2>

=0.45

<fact2>

=0.4

<No2>

=0

Bracket thickness

= 1

Then stiffener number 2 will be located 0.45*Z from (and parallel to) the free edge.

Let A = L0*t/10. The profile size (among the available standard dimensions) will be selected whose cross-section area is closest to 0.4*A.

Following example corresponds to the situation for a bracket that may have up to three stiffeners. Three different patterns must be defined corresponding to the case that the bracket has 1, 2 and 3 stiffeners, respectively.

Example:

First the case with only one stiffener.

PATTERN , PAT_A_1

/ NO_STI = 1
/ RULE = 1
/ LOCATION = 20
/ SIZE_FACTOR = 1.0
/ LENGTH_NO = 0;

The pattern definition for the same bracket when there are two stiffeners should be:

PATTERN , PAT_A_2

/ NO_STI = 2
/ RULE = 1
/ LOCATION = (20, 0.4)
/ SIZE_FACTOR = (0.6, 0.4)
/ LENGTH_NO = (0, 0);

Finally in case of three stiffeners:

PATTERN , PAT_A_3

/ NO_STI = 3
/ RULE = 1
/ LOCATION = (20, 0.28, 0.59)
/ SIZE_FACTOR = (0.6, 0.4, 1.0)
/ LENGTH_NO = (0, 0, 3);

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