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Figure 1: Two-surface Model Definition (a) Stress Space, (b) A36 Steel Cyclic Response
E-shaped Metallic Damper Analysis
The Italian company ALGA has developed a seismic isolation system consisting of lubricated sliding
bearings to resist gravitational load and energy dissipating devices shaped like the capital letter "E" to
dissipate horizontally transmitted destructive earthquake energy. A pair of E-shaped devices is
responsible for the dissipation of energy in one direction. Therefore, two pairs are used in one bearing
to dissipate the horizontally transmitted energy. The central leg and external legs are hinge-connected
to the top and bottom plates of the sliding bearings.
The two-surface model discussed in the previous section is now applied in a finite element study of the
cyclic response of the E-damper. A deformed shape plot of the damper obtained with plane stress
elements is shown for the maximum displaced position in Fig. 2a, while load-displacement curves
from the numerical model and experimental testing (Marioni, 1991) are compared in Fig. 2b. The
overall agreement is quite good, particularly since the constitutive model parameters were determined
independently from the damper experiments. Although some minor differences exist, relating
primarily to the material stabilization processes, the detailed plastic strain distributions could be used
for a preliminary assessment of durability.
KT7
•
Marioni (1991)
30 . Two Surface Model
20
~ 10
« / r
-150 -100 -50 0 50 100 150
Displacement (mm)
Figure 2: E-Damper (a) Deformed Shape, (b) Cyclic Response