Models for Simulating the Seismic Response of Concrete Structures - Dynamic Behavior of Concrete and Seismic Engineering - page 269

Thus, the hysteresis loops are broader and the dissipated energy higher. An
important strength cyclic deterioration occurs during the cyclic loading. This can be
seen in Figure 7.32, as collapse takes place during the last loop of loading for 8 cm
displacement in the X direction and -8 cm displacement in the Y direction.

Comparing Figures 7.31 and 7.32 shows that the important phenomena observed
during the tests (stiffness deterioration, strength cyclic deterioration) are correctly
reproduced by the 3D model shell. Recent works have shown that for the same
problem it was also possible to achieve good results with enriched Timoshenko
multi-fiber elements [KOT 00].

800

CALCULATION
EXPERIENCE

600

400

200

0

-200

-400

-600

-1000 -800 -600 -400 -200 0.0 200 400 600 800

X Load (KN)

Figure 7.32. USW3 test: graph of the load evolutions in X and Y directions during the test

7.5. Conclusions

In this chapter, we showed some peculiarities of the functioning of RC structures
under seismic loading and demonstrated the need to have efficient modeling tools to
analyze their responses. This results in two major aspects to be considered:

- representation of the structure with its associated masses;

- relevance of the behavior models to use for both materials and interfaces
(between the materials and between structure and support).

The choice should be made according to the expected accuracy of the results and
the opportunity of expressing simplifying hypotheses.

With slender structures, frames and structural walls, the effectiveness of semi-
global models (multi-fiber or multi-layer beams) has been proved, if the constitutive