Page 311 - Advanced Design Examples of Seismic Retrofit of Structures

300 Advanced Design Examples of Seismic Retrofit of Structures

M OT X 1394:77
M ST X > ) 888 > ¼ 406:4T mÞ
ð
C 1 C 2 J 1:43 1:2 2
1394:77
M OT Y
M ST Y > ) 1420:8 > ¼ 406:4T mÞ
ð
C 1 C 2 J 1:43 1:2 2
1394:77
M OT X
0:9M ST X > ) 0:9 888 ¼ 799:2 > ¼ 101:65 T mÞ
ð
C 1 C 2 R OT 1:43 1:2 8
1394:77
M OT Y
0:9M ST Y > ) 0:9 1420:8 ¼ 1278:72 >
C 1 C 2 R OT 1:43 1:2 8
ð
¼ 101:65 T mÞ
As can be seen, dead loads can adequately resist the effects of overturning in
both buildings.
5.5.7 Modeling Assumptions
In this example, the analysis method is the linear and nonlinear static procedure.
The nonlinear behavior of structural members is concentrated in plastic hinges
at most suitable locations. The characteristics of the plastic hinges follow the
dominant behavior of each structural member. In the main building, because
the only structural members to carry the lateral loads are infill walls, the axial
force plastic hinges (P) are defined in these members. No plastic hinges are
defined in columns and beams. The columns are modeled as force-controlled
members. The beams are checked against gravity loads. The plastic hinge char-
acteristic of a typical infill wall in the main building is illustrated in Fig. 5.4.
For the sports building, the axial force plastic hinges (P) are assigned to the
braces and the truss members of the girders at the mid-length of these members.
The axial force-flexural moment interaction plastic hinge (PMM) is considered
for the columns with (P UF /P CL ) 0.5 and for the upper and lower ridge in the
truss girders. These hinges are defined at 15% and 85% of the length of columns
and at both ends of the upper and lower ridges in the truss girders in the sports
building. The column hinges in the main building are defined at 10% and 90%
of the length of columns. Plastic hinge characteristics of the braces, columns,
and girders ridge are shown in Figs. 5.5–5.8. A view of the numerical models
of the main and sports buildings is shown in Fig. 5.9.

5.6 CAPACITY FORCES CALCULATIONS

Where evaluating the behavior of deformation-controlled actions, the expected
strength, Q CE , shall be used. Q CE is the expected strength of a deformation con-
trolled action of an element at the deformation level under consideration and is
defined as the mean value of resistance of a component at the deformation level
anticipated for a population of similar components, including consideration of
the variability in material strength and strain hardening and plastic section
development [7].