EUROCODE 2 WORKED EXAMPLES - Federbeton

EC2 – worked examples 6-44
single column fixed at the base and free at his top, so that the relevant Kx/y stiffness is
valuable as:
EI
Kx/y
=
H
3 3
where E is the Young modulus, I the inertia and H the height of the column. For the
vertical direction, the intrinsic stiffness of pot-bearing is assumed, considering the
substructure vertical behaviour as rigid.
For the sake of simplicity the calculus of the relevant stiffness is omitted and the final
values of the spring constants are reported in table 6.6 .
Location
Kx,tot
10
Ky,tot Kz,tot
6 kN/m 10 6 kN/m 10 6 �
�
�
kN/m
Abutment A 9.55 178.80 10.02
Pier P1 4.74 11.61
Pier P2 2.66 11.61
Abutment B 2.78 10.02
Table 6.6 Stiffness for restraining elements
It can be noticed that the previous values are referred to the overall stiffness of the
restraint, thus the elastic constant of any individual spring element may be obtained
dividing the K values of table 6.6 by the number of element representing the restraint or
the supports.
Prestressing forces
Two orders of prestressing tendons are arranged (in longitudinal and transverse directions)
in order to avoid any tensile stress in concrete at service (required by railway code). The
initial tensile stress of tendon is:
σpo,max = 0.85 fp 0.1k = 0.85 × 1600 = 1360 MPa.
The number of tendons is 39 for the longitudinal direction and 64 for the transverse one.
Each tendon is built up with 19 strands φ 0.6” having an area of 1.39 cm 2 . Fig. 6.35 reports
tendon’s layout for half deck, being symmetrically disposed.
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