Specification of polygon points of pipeline configuration through coordinate differences and height levels (Input Table)

Data description/conditions:


Identification name of polygon point (n)

Undefined / Required at start and end of a weak element (see also ETYP below). Name must be unique.


X-coordinate difference between polygon point (n) and (n-1)

None / Required 1


Y-coordinate difference between polygon point (n) and (n-1)

None / Required 1


Z-coordinate of polygon point (n)

None / Required 1


Radius of pipe bend at polygon point (n)

0. / Undefined 1 4

(BENDRAD = 0. means a 'stiff' mitre bend (no bending stiffness reduction). At the last data line a BENDRAD value > 0. is ignored.)


Type of element/bend

Undefined / Prescribed names: Elastic / Weak / Odd Elements / Mitre bend 1 4

(Undefined: Normal bend (if BENDRAD > 0).
Prescribed names:
Elastic: Elastic bends to be specified in Geometric non-linear modules only.
Weak: Weak elements are elements / polygon lines without axial and flexural stiffness providing the possibility to specify branched connections. Points to be connected must have a unique IDENT.
Odd Elements: Odd Elements means that the number of elements generated in a bend is odd.
Mitre bend: a mitre bend is defined by N-KINK in combination with either L-SEGM or BENDRAD.)


Nominal bend element length in bend at polygon point (n)

> 0. / Undefined 1 4 (for the recommended length see 2 3)

(The specified BEND ELEMENT LENGTH is the element length along the arc.)

Warning In case of a mitre bend 3 BEND.EL should be ≤ L1 = r/2(1+tan α)


Nominal pipe element length on polygon line from point(n-1) to(n)

> 0. (for the recommended length see 2)

(Best practice element length is once or twice the pipe diameter.)


Number of pipe elements with bend element length extending at both sides of the bend at polygon point (n)

> 0 / Undefined 1 4

(In case available pipe length between bend tangent points is not sufficient for the bend extension(s) specified, the number of extension elements will be reduced automatically to match the available pipe length. Extension elements have straight pipe properties, unless the bend is specified to be elastic. In that case a curvature will be assigned to the extension elements decreasing linearly from 1/BENDRAD at the bend side to zero at the straight pipe side. Note: Coordinates remain unchanged!)


The number of kinks in a mitre bend

> 0 3 4  (or Undefined in case of no mitre bend)


The length of a mitre bend segment (Space)

> 0. 3 4  (or Undefined in case of no mitre bend)



¹ see also data conditions at Table error description

² Recommended element length

maximum element length a = nmax* D
minimum length of pipeline at both sides A = mmin* D
k is the soil stiffness along the pipeline axis

(Example in graph: D = 500 mm, t = 10 mm, k = 10-2 N/mm3, E = 2.1 105 N/mm2 : kD/E = 2.4 10-5 )

Recommended element length

In case the assigned element length is more than 4/3 of the recommended element length W500/24 is reported in the NOTICES table. In case the length exceeds the recommended length M300/1 and M500/6 are reported.

3 Mitre bend data:

When ETYP is defined as 'Mitre bend' N-KINK should have a value > 0. The shape of the bend is defined by either the length of the segments L-SEGM or by the bend radius BENDRAD. When L-SEGM is assigned a value BENDRAD is not editable and the calculated bend radius is reported in M-CDATA and SHAPEP. When L-SEGM is left empty BENDRAD shoud have a value and the mitre segment length L-SEGM is calculated and reported in M-CDATA.

For a single kink mitred bend L-SEGM in table POLYDIF should be calculated as close as feasible  to 2 x L1 (as shown below) in order to get accurate results. The value of L1 is reported in table BENDFAC, but can also be calculated using the formula.


The maximum element length of a mitre bend generated is 0.5 x L-SEGM, so the minimum number of elements between two kinks is 2.
For a single kink mitred bend the bend element length specified should not exceed the value of L1.

When ETYP is not defined as 'Mitre bend' both N-KINK and L-SEGM are not editable.

4 Please refer to the table description for the changed POLYDIF functionality.

H200121, last changed: 12/6/2019

See also:

Table description

Table error description