Home > List of Keywords > *BEAMPRO2

*BEAMPRO2

Data format:

An arbitrary number of lines with 11 parameters each, as follows:

IPRO ITRUETENS AIRIN WT OD DBUOY XJ63 XJ36 DENDCAP CL DCONT
...

Status:

Optional

Purpose:

To define geometrical properties of a set of beam elements previously defined by global stiffnesses (*BEAMPRO)

Details :

Parameter	Description
IPRO	Identification number referring to a keyword *BEAMPRO previously defined.
ITRUETENS	A flag to select whether the axial behavior of the line is defined with respect to the effective tension or to the true wall tension. ITRUETENS = 0 (default): The axial behavior of the riser is given with respect to the effective tension; ITRUETENS = 1 : The axial behavior of the riser is given with respect to its true tension;
AIRIN	Internal cross section of the riser (m2);
WT	Wall thickness of the riser (m);
OD	Outer diameter of the riser (m)
DBUOY	Buoyancy diameter (m)
XJ63	= 0 (obsolete)
XJ36	= 0 (obsolete)
DENDCAP	End cap diameter (m)
CL	Lift coefficient (used if contact and *LIFTOPTION is defined)
DCONT	Contact diameter (m)

Note

Classically, the presence of a fluid inside and outside the riser is accounted for resorting to the effective tension concept. The true tension is linked to the effective tension by the following relationship :

$T_{true} = T_eff - P_e S_e + P_i S_i$

Where: - $P_e$ is the external pressure due to sea water hydrostatic pressure, - $P_i$ is the internal fluid pressure, - $S_e$ is the external section of the pipe calculated from the hydraulic diameter : $S_e = \pi * D_h^2/4$ - $S_i$ is the internal cross section (AIRIN hereabove).

The same relation exists between the stresses. The true axial stress $\rho_{real}$ is deduced from the effective stress $\rho_{eff}$ : $\rho_{real} = \rho_{eff} + \rho_{p}$ with $\rho_p = \frac{P_i S_i - P_e S_e}{S_e - S_i}$
The total apparent weight of the global system riser + fluid is used in the calculations and the resulting effort is then the effective tension. A special attention must be paid to the link between the axial strain of the riser and the effective tension : - When a multi-linear axial stiffness is defined, it is important to distinguish the effective tension from the true tension. When ITRUETENS=1, the axial behaviour is expressed in terms of the true tension; - On the other hand, due to the Poissons coefficient, the fluid pressures change the axial strain. When ITRUETENS=1,the axial strain is corrected the pressures effect.