4.5 Seismic Responses under Long-Period Ground Motions
4.5.2 Response of maximum story drift angle
Firstly, we conduct time-history dynamic analysis on various high-rise steel building models under severe earthquakes that incorporating the synthetic long-period ground motions (C-San-EW, YKL-NS, WOS-EW) and the observed severe ground motions (MYG004-NS, CHB009-NS) in Great East Japan earthquake, 2011. Maximum story drift angle response of the i-story of moment-frame structures are calculated by
, , 1
,
max i max i max i
hi
(4.5) Where, max,i and max,i-1 are respectively instantaneous maximum horizontal drifts of i and i-1 story, hi is the story-height of i story. Thus, according to Eq. (4.5), the responses of maximum story drift angle of various high-rise steel buildings is computed as shown in Figures 4.10~4.18. Figures4.10~4.18 (a) demonstrate the maximum story drift angles of building models under the earthquakes (Art-Hachi, El-Centro-NS, Hachinohe-NS, Taft-EW and WOS-EW) scaled to Level 1 (PGV=0.25m/s). Figures 4.10~4.18 (b) show the maximum story drift angles of building models under the earthquakes (Art-Hachi, El-Centro-NS, Hachinohe-NS, Taft-EW, CHB009-NS and C-San-EW) scaled to Level 2 (PGV=0.5m/s). Figures 4.10~4.18 (c) demonstrated the maximum story drift angles of building models under the earthquakes (MYG004-NS and YKL-NS) over Level 2 (PGV=0.5m/s).
According the maximum story drift angle responses of various high-rise building models demonstrated in Figures 4.10~4.18, several relations between seismic resistant capacity and structural performance can be founded below.
(a) We could briefly find out that seismic demands of level 1 and level 2 (max ≤0.005 for level 1 demand, max ≤0.01 for level 2 demand) could not be satisfied by when subjected to synthetic long-period ground motions, e.g., C-San-EW (near PGV of Level 2) excited relatively large max on 20S and 30S building models (max>0.01rad). In contrast, WOS-EW (near PGV of Level 1) tends to have larger excitations on 30S and 40S building models (max>0.005rad). These seismic response observations indicate that the existent high-rise steel buildings (height: 81m~160m) might have large risks to satisfy seismic demands under severe earthquakes with long period component.
(b) As for the relation between story level (20, 30, 40) and maximum story drift angle response, large variability is captured, because the characteristics of each ground motions has different influence on the seismic capacity of the correspondingly different models that have various natural vibration features. This finding further proves that long-period ground motions tend to have larger uncertainty on the seismic response of high-rise buildings. Furthermore, long-period ground motions induced in varied basin-areas may have associated different seismic excitations, e.g., C-San-EW wave shows extremely large excitation on the structure with ‘first-mode’ natural period (T1) between 2~4sec, and WOS-EW likewise influences the structure with T1 between 4.5~5.5sec (AIJ 2007).
(c) By comparing the maximum story drift angle response of each building model subjected to observed long-period ground motion (CHB009-NS) and largest observed ground motion in great east Japan earthquake (2011). As shown in Figures 4.10~4.18 (c), with respect to the earthquake over Level 2, period of vibration is short. In this case, max responses are relatively small even with long period component.
0 5 10 15 20
0 0.005 0.01
Art-Hachi El-Centro NS Hachinohe NS Taft EW WOS-EW
Level 1
max 20S-FA
c-FA
b (with-deterioration)
Story level
0 5 10 15 20
0 0.005 0.01 0.015
Art-Hachi El-Centro-NS Hachinohe-NS Taft-EW CHB009-NS C-San-EW
Level 2
max 20S-FA
c-FA
b (with-deterioration)
Story level
0 5 10 15 20
0 0.005 0.01 0.015
MYG004-NS YKL-NS 20S-FA
c-FA
b (with-deterioration)
max (rad) Level 2 Level 1
Story level
(a) Level 1 (b) Level 2 (c) Oversize Figure 4.10 20S-FAc-FAb model
Chapter 4. Evaluation of Seismic-Resistant Capacity of Existent High-Rise Steel Buildings
0 5 10 15 20
0 0.005 0.01
Art-Hachi El-Centro NS Hachinohe NS Taft EW WOS-EW Level 1
max 20S-FA
c-FB
b (with-deterioration)
Story level
0 5 10 15 20
0 0.005 0.01 0.015
Art-Hachi El-Centro-NS Hachinohe-NS Taft-EW CHB009-NS C-San-EW
Level 2
max 20S-FA
c-FB
b (with-deterioration)
Story level
0 5 10 15 20
0 0.005 0.01 0.015
MYG004-NS YKL-NS 20S-FA
c-FB
b (with-deterioration)
max (rad) Level 2 Level 1
Story level
(a) Level 1 (b) Level 2 (c) Oversize Figure 4.11 20S-FAc-FBb model
0 5 10 15 20
0 0.005 0.01
Art-Hachi El-Centro NS Hachinohe NS Taft EW WOS-EW Level 1
max 20S-FB
c-FB
b (with-deterioration)
Story level
0 5 10 15 20
0 0.005 0.01 0.015
Art-Hachi El-Centro-NS Hachinohe-NS Taft-EW CHB009-NS C-San-EW
Level 2
max 20S-FB
c-FB
b (with-deterioration)
Story level
0 5 10 15 20
0 0.005 0.01 0.015
MYG004-NS YKL-NS 20S-FB
c-FB
b (with-deterioration)
max (rad) Level 2 Level 1
Story level
(a) Level 1 (b) Level 2 (c) Oversize Figure 4.12 20S-FBc-FBb model
0 10 20 30
0 0.005 0.01
Art-Hachi El-Centro NS Hachinohe NS Taft EW WOS-EW Level 1
max 30S-FA
c-FA
b (with-deterioration)
Story level
0 10 20 30
0 0.005 0.01 0.015
Art-Hachi El-Centro-NS Hachinohe-NS Taft-EW CHB009-NS C-San-EW Level 2
max 30S-FA
c-FA
b (with-deterioration)
Story level
0 10 20 30
0 0.005 0.01 0.015
MYG004-NS YKL-NS 30S-FA
c-FA
b (with-deterioration)
max (rad) Level 2 Level 1
Story level
(a) Level 1 (b) Level 2 (c) Oversize Figure 4.13 30S-FAc-FAb model
0 10 20 30
0 0.005 0.01
Art-Hachi El-Centro NS Hachinohe NS Taft EW WOS-EW Level 1
max 30S-FA
c-FB
b (with-deterioration)
Story level
0 10 20 30
0 0.005 0.01 0.015
Art-Hachi El-Centro-NS Hachinohe-NS Taft-EW CHB009-NS C-San-EW Level 2
max 30S-FA
c-FB
b (with-deterioration)
Story level
0 10 20 30
0 0.005 0.01 0.015
MYG004-NS YKL-NS 30S-FA
c-FB
b (with-deterioration)
max (rad) Level 2 Level 1
Story level
(a) Level 1 (b) Level 2 (c) Oversize
0 10 20 30
0 0.005 0.01
Art-Hachi El-Centro NS Hachinohe NS Taft EW WOS-EW Level 1
max 30S-FB
c-FB
b (with-deterioration)
Story level
0 10 20 30
0 0.005 0.01 0.015
Art-Hachi El-Centro-NS Hachinohe-NS Taft-EW CHB009-NS C-San-EW Level 2
max 30S-FB
c-FB
b (with-deterioration)
Story level
0 10 20 30
0 0.005 0.01 0.015
MYG004-NS YKL-NS 30S-FB
c-FB
b (with-deterioration)
max (rad) Level 2 Level 1
Story level
(a) Level 1 (b) Level 2 (c) Oversize Figure 4.15 30S-FBc-FBb model
0 5 10 15 20 25 30 35 40
0 0.005 0.01
Art-Hachi El-Centro NS Hachinohe NS Taft EW WOS-EW
Level 1
max 40S-FA
c-FA
b (with-deterioration)
Story level
0 5 10 15 20 25 30 35 40
0 0.005 0.01 0.015
Art-Hachi El-Centro-NS Hachinohe-NS Taft-EW CHB009-NS C-San-EW
Level 2
max 40S-FA
c-FA
b (with-deterioration)
Story level
0 5 10 15 20 25 30 35 40
0 0.005 0.01 0.015
MYG004-NS YKL-NS 40S-FA
c-FA
b (with-deterioration)
max (rad)
Story level
(a) Level 1 (b) Level 2 (c) Oversize Figure 4.16 40S-FAc-FAb model
0 5 10 15 20 25 30 35 40
0 0.005 0.01
Art-Hachi El-Centro NS Hachinohe NS Taft EW WOS-EW 40S-FA
c-FB
b (with-deterioration)
Level 1
max
Story level
0 5 10 15 20 25 30 35 40
0 0.005 0.01 0.015
Art-Hachi El-Centro-NS Hachinohe-NS Taft-EW CHB009-NS C-San-EW 40S-FA
c-FB
b (with-deterioration)
Level 2
max
Story level
0 5 10 15 20 25 30 35 40
0 0.005 0.01 0.015
MYG004-NS YKL-NS 40S-FA
c-FB
b (with-deterioration)
max (rad)
Story level
(a) Level 1 (b) Level 2 (c) Oversize Figure 4.17 40S-FAc-FBb model
0 5 10 15 20 25 30 35 40
0 0.005 0.01
Art-Hachi El-Centro NS Hachinohe NS Taft EW WOS-EW
Level 1 40S-FB
c-FB
b (with-deterioration)
max
Story level
0 5 10 15 20 25 30 35 40
0 0.005 0.01 0.015
Art-Hachi El-Centro-NS Hachinohe-NS Taft-EW CHB009-NS C-San-EW 40S-FB
c-FB
b (with-deterioration)
max
Level 2
Story level
0 5 10 15 20 25 30 35 40
0 0.005 0.01 0.015
MYG004-NS YKL-NS 40S-FB
c-FB
b (with-deterioration)
max (rad)
Story level
(a) Level 1 (b) Level 2 (c) Oversize Figure 4.18 40S-FBc-FBb model
Chapter 4. Evaluation of Seismic-Resistant Capacity of Existent High-Rise Steel Buildings In addition, the effect of member deteriorations (FA, FB for girder and column) on the maximum story drift angle responses of various building models (20S, 30S and 40S) is not overtly observed, by comparing the maximum story drift angle of the building model with deterioration and that without deterioration. However, certain slight effect of deterioration on maximum story drift angle is produced, which means that local-buckling of steel members is initiated by strength and stiffness deterioration. This phenomenon becomes more and more notable from the toughest building model FAc-FAb to intermediate building model FAc-FBb and finally to weakest building model FBc-FBb. For instance, mild effect of member deterioration is derived in 40S-FAc-FAb
model under WOS-EW and MYG004-NS, as shown in Figure 4.19. This amplified effect on max
may be increased by seismic excitations with larger intensity.
0 10 20 30 40
0 0.005 0.01 0.015
with-deterioration non-deterioration 40S-FBc-FBb (WOS-EW)
max (rad)
Story level
0 10 20 30 40
0 0.0025 0.005 0.0075 0.01
with-deterioration non-deterioration 40S-FBc-FBb (MYG004-NS)
max (rad)
Story level
(a) WOS-EW (b) MYG004-NS Figure 4.19 Effect of member deterioration on the max of 40-story model
Seismic responses of the FAc-FAb building models with various heights under C-San-EW, WOS-EW and YKL-NS are demonstrated in Figure 4.20, based on the normalised height in vertical direction. The dependence of the relation between long-period ground motion characteristics and the natural period of high-rise building structures on the seismic responses is clarified since each long-period ground motion has its special effective range. Hence, for the existent high-rise steel buildings, seismic assessment should be specifically conducted by considering the characteristics of long-period ground motions.
0 0.25 0.5 0.75 1
0 0.005 0.01 0.015
with deterioration non deterioration
Normalized storey level
FAc-FA
b (WOS-EW)
20S
40S
30S
max (rad)
0 0.25 0.5 0.75 1
0 0.005 0.01 0.015
with deterioration non deterioration
Normalized storey level
FAc-FA
b (C-San-EW)
40S
20S 30S
max (rad)
0 0.25 0.5 0.75 1
0 0.005 0.01 0.015
with deterioration non deterioration
Normalized storey level
FAc-FA
b (YKL-NS)
40S
30S 20S
max (rad)
(a) Osaka district (b) Nagoya district (c) Tokyo district
Figure 4.20 Effect of the characteristics of ground motions on max of 20S, 30S and 40S building models