When do the sliding saddles start to move in AutoPIPE Vessel?
It depends of the friction factor inputted in the dialog of the saddles between the sliding saddles and the concrete or the plate under the sliding saddles.
A small friction factor value indicates that a PTFE plate or in some cases rolling bars have been installed.
The values of the longitudinal loads (RaHL) are calculated as follow:
No.
Support saddles Location (mm) Stiffness (daN/mm)
Vertical
Horizontal
Combined
Reactions (daN)
Shear Loads (daN)
Bending moments (daN∙m)
Reactions Transverse (daN)
Reactions Longitudinal (daN)
1
500.0
2,716.2
-324.1 2,392.2
-144.2 -2,424.7
0.0
2,402.7
2
4,500.0
4,190.7
-1,623.1 2,567.7
-2,245.8 -697.1
-1,629.2
3
8,500.0
2,057.6
-1,433.9 623.8
-1,134.0 -744.0
-521.1
4
11,500.0
673.9
-349.8 324.1
-333.5 -144.2
-252.4
The fixed saddle is located in this example on the left hand.
Run the model with a friction factor equal to 0 and you will obtain the values of vertical reaction loads used for the calculation of RaHL (as shown here after):
2,162.0
-324.1 1,837.9
-144.5
5,253.1
-2,177.3 3,075.8
-2,181.7
1,559.4
-925.8 633.7
-585.1
664.0
-339.9 324.1
In this example, the mass of the each saddle is 181 kg (177.4 daN).
The friction factor is equal to 0.3
The loads on the sliding saddles are equal to:
W2ini = 5253.1 + 177.4 = 5430.5 daN --> RaHL2 = 5430.5 x 0.3 = 1629.2 daN
W3ini = 1559.4 + 177.4 = 1736.8 daN --> RaHL3 = 1736.8 x 0.3 = 521.1 daN
W4ini = 664 + 177.4 = 841.4 daN --> RaHL4 = 841.4 x 0.3 = 252.4 daN
The sign is –ve for these loads.
The system is on equilibrium --> Sumation of RaHL = 0
The load on the fixed saddle is equal to: RaHL1 = 1629.2 + 521.1 + 252.4 = 2402.7 daN
When the longitudinal loads exist, the vertical loads are modified. These modified values are due to the moments