Page 243 - Advanced Design Examples of Seismic Retrofit of Structures

236 Advanced Design Examples of Seismic Retrofit of Structures

The Results
The results of evaluation of infill panels under the deformation-controlled
actions according to Section “Deformation-Controlled” are shown in
Table 4.13. As can be seen, none of the infill panels meets the acceptance cri-
teria as set out in Section “Deformation-Controlled,” and hence all of them
should be considered for retrofit. As an example, calculations for infill panel
A-1-3 in the floor story are presented. It is noted that in calculation of the
expected capacity of the bare frame (V fre ), only the sum of the shear capacity
of the columns in this frame is considered.
h inf ¼280 cm, L inf ¼540 cm, t inf ¼20 cm, a¼31 cm
280
θ ¼ tan 1 h inf ¼ tan 1 ¼ 27:41degrees
L inf 540
2 9
Left column : 2UNP22PL24 1 ! A s ¼ 41:57 cm =
! A s min
Right column : 2UNP18PL24 1 ! A s ¼ 32:77cm 2 ;
2
¼ 32:77cm and C v ¼ 1:0
f m ¼5 MPa, F y ¼240 MPa
a t inf f me cosθ 31 20 50 cos 27:41Þ
ð
V inf ¼ Q CE ¼ ¼ ¼ 11;008 kg
2:5 2:5
V fre ¼ 0:6F y A s C v ¼ 0:6 2400 32:77 1:0 ¼ 47;189 kg
8
V fre 47,189
β ¼ ¼ ¼ 4:287
>
>
< 11,008
V inf
! based onTable 4:12 : m ¼ 6:07
L inf 540
>
¼
> ¼ 1:93
:
h inf 280
Table 4.14 shows the checking of the compact section of the columns of the
example building. In addition, the results of evaluation of the columns under
displacement-controlled and force-controlled actions are presented in
Table 4.15.
According to ASCE 41 [1], the acceptance criteria of steel columns under
combined axial compression and bending stress, where the axial column load
is less than 50% of the lower-bound axial column strength, P CL , the column
shall be considered deformation-controlled for flexural behavior and force-
controlled for compressive behavior and the combined strength shall be evalu-
ated by Eq. (4.32) or (4.33).
P UF
For 0:2 0:5
P CL
8 (4.32)
P UF M x M y
+ + 1:0
P CL 9 m x M CEx m y M CEy