Ans: It depends on the friction factor input 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.
How are the RaHL values calculated? 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 – for these loads.
The system is on equilibrium è S 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