Page 33 - DOUCE HYDRO 2013

33
Improvements
by using dampers
P R O T E C T I O N S
Without damper (= 1 fixed pier)
Let consider a bridge with 4 spans, L=300m, M=10 000 t, to protect against a
longitudinal earthquake with the following data:
Soil type: EC8-B and PGA = 2m/s².
The deck is supported by 5 identical piers (P1 to P5) with a longitudinal
stiffness of Kp = 300 MN/m.
In case of earthquake, the central pier must resist at 17 400 kN (shear Force)
With dampers
If dampers are installed on some piers, they will dissipate a large part of the seismic energy and therefore,
reduce the forces in the fixed pier.
1 fixed pier + 2 dampers: the dissipation of energy allows reducing the total force at 10 375 kN.
Comparison with and without dampers
1 fixed pier =
no damper, no STU
Central Pier must resist at 17400 kN
(shear Force)
1 fixed pier + 2 dampers
The dissipation of energy allows to reduce
the total Force at 10375 kN
Acceleration
1 fixed pier
1 fixed pier + 2 dampers
Maximum acceleration
of the deck
Period