Models for Simulating the Seismic Response of Concrete Structures - Dynamic Behavior of Concrete and Seismic Engineering - page 252

Second floor of the frame without any filling
Figure 7.13. Examples of the relative displacement-transverse load relationship between
storeys for an earthquake with a 975 year return period
For both structures, little damage could be observed for the 475-sequence period
earthquake, whereas important displacement values (tests stopping before the end of
the signal to allow the structure to be repaired) were reached for 975 (Figure 7.14)
and 2,000 sequence period earthquakes respectively, for both the infilled frame and
the frame without any infill.
The collapse mode is also different from one structure to the next: the damage is
concentrated within the second-floor columns for the frame without any infill
whereas the ground floor that has important openings (door and windows)
constitutes the critical storey of in-filled frame.
7.4.1.2. Modeling and comparison with experiments
For time dynamic calculations, the reinforced concrete frame has been modeled
with beam elements and the fiber model described previously. Each column and
beam has been modeled in three parts: the two plastic hinges have been chosen to be
non-linear, whereas the central part is considered as elastic with cracked stiffness.
The masonry in filled walls has been modeled as diagonal truss rods (stiffness and
strength) and has been determined with plane stress 2D refined calculations. These
calculations allow us to estimate the drop in stiffness and strength caused by the
appearance of openings.
Figure 7.14 shows a test-calculation comparison for the frame without infill for a
high earthquake level (475-sequence period). Thus, non-linear models can assess the
displacement and global strength of a structure. Furthermore, these calculations
highlight the concentration of strains and damage on the second floor, as was the