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Seismic Analysis of
Multi-storied RC Building
Presented by .
Rahul Leslie
Part - II
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Analysis as per IS:1893-2002
Seismic Coefficient Method
(Static Analysis)
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Static analysis: The time period of the structure is determined using
(7.6.1 & 7.6.2, IS:1893(Part 1)-2002)
RC frames without brick infillsh = height of building in m
RC frames with brick infillsd = base dimension in m
Seismic Analysis of Multi-storied RC Building Presented by Rahul Leslie
Buildings with shear walls(7.6.3, IS:1893(Part 1)- Proposed Draft)Aw = total effective area of shear
walls in the 1ststorey, in m2
Awi = effective cross sectional area
of shear wall iin the 1
st
storeyLwi = length of shear wall iin the
1ststorey considered in the
direction of the lateral forces, in m
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Static analysis: The time period of the structure is determined using
(7.6.1 & 7.6.2, IS:1893(Part 1)-2002)
RC frames without brick infillsh = height of building in m
RC frames with brick infillsd = base dimension in m
The Design horizontal seismic coefficient Ah iscalculated from (6.4.2, IS:1893(Part 1)-2002)
Zone factor Z (Table 2, IS:1893(Part 1)-2002)
Importance factor I (Table 6, IS:1893(Part 1)-2002)
Response reduction coefficient R (Table 7, IS:1893(Part 1)-2002)
Horizontal Acceleration coefficient Sa/g
Seismic Analysis of Multi-storied RC Building Presented by Rahul Leslie
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Static analysis: Importance factor (Table 6, IS:1893(Part 1)-2002)
I = 1.5 for special buildings
I = 1.0 for other buildings
Response reduction factor (Table 7, IS:1893(Part 1)-2002) R = 3 for ordinary detailing (with ordinary detailed shear
wall, if any) R = 5 for ductile detailing (with ductile detailed shear wall, if
any) ie., as per IS:13920-1993
R = 4 for ductile detailing with ordinary detailed shear wall
R = 4.5 for ordinary detailing with ductile detailed shear wall
Seismic Analysis of Multi-storied RC Building Presented by Rahul Leslie
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Static analysis (cont): Where the Horizontal acceleration Sa/g is determined
from the Response Spectrum curve (Fig.2, IS:1893(Part
1)-2002)
Seismic Analysis of Multi-storied RC Building Presented by Rahul Leslie
(Fig.2, IS:1893(Part 1)-Proposed Draft)
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Static analysis (cont): Where the Horizontal acceleration Sa/g is determined
from the Response spectrum curve (Fig.2, IS:1893(Part 1)-
2002)
Seismic Analysis of Multi-storied RC Building Presented by Rahul Leslie
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Static analysis (cont): Where the type of soils are
Type I (Rock or Hard soil): N > 30, among other descriptions
Type II (Medium soils): 10 N 30 for all soils
N >15 for poorly graded, among
other descriptions
Type III (Soft soils): N < 10
(Table 1, IS:1893(Part 1)-2002)
Seismic Analysis of Multi-storied RC Building Presented by Rahul Leslie
Stiff Soil
(Table 1, IS:1893(Part 1)- Proposed Draft)
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Static analysis (cont): The base shear is determined by (7.5.3, IS:1893(Part 1)-
2002)
Design lateral force for each level is determined by(7.7.1, IS:1893(Part 1)-2002)
Seismic Analysis of Multi-storied RC Building Presented by Rahul Leslie
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An Example
A simple six storied structure
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Lumped mass model
Presented by Rahul LeslieSeismic Analysis of Multi-storied RC Building
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height 18 m
Period 0.075x180.75 = 0.6554 sec
Presented by Rahul LeslieSeismic Analysis of Multi-storied RC Building
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height 18 m
Period 0.075x180.75 = 0.6554 sec
Sa/g 1.5258
Ah (0.16x1)/(2x3) x 1.5258 = 0.0407
W (kN)
0
23.57
23.57
23.57
23.57
23.57
23.57
SW 141.42
h2
02
32
62
92
122
152
182
Wh2
0
212.13
848.52
1909.17
3394.08
5303.25
7636.68
19303.83
*=
Presented by Rahul LeslieSeismic Analysis of Multi-storied RC Building
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SW*(Wh2/
SWh2)
0
1.5541
6.2163
13.9866
24.8651
38.8516
55.9464
=141.42
19303.83x
Wh2
0
212.13
848.52
1909.17
3394.08
5303.25
7636.68Qi (kN)
0
0.0632
0.2529
0.5691
1.0117
1.5807
2.2763
=x
SW*(Wh2
/SWh2)
0
1.5541
6.2163
13.9866
24.8651
38.8516
55.9464
0.0407
Presented by Rahul LeslieSeismic Analysis of Multi-storied RC Building
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Levels W (kN) h (m) Wh2SW*(Wh2/
SWh2) Qi (kN)
1 0 0 0 0 0
2 23.57 3 212.13 1.5541 0.06323 23.57 6 848.52 6.2163 0.2529
4 23.57 9 1909.17 13.9866 0.5691
5 23.57 12 3394.08 24.8651 1.0117
6 23.57 15 5303.25 38.8516 1.5807
7 23.57 18 7636.68 55.9464 2.2763
SW 141.42 (kN) 19303.83 141.42 kN 5.7539 kN
Vb 5.7539 (kN)
height 18 m
Period 0.6554 sec
Sa/g 1.5258
Ah 0.0407
Presented by Rahul LeslieSeismic Analysis of Multi-storied RC Building
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The forces are applied and analysed
Presented by Rahul LeslieSeismic Analysis of Multi-storied RC Building
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The forces are applied
Presented by Rahul LeslieSeismic Analysis of Multi-storied RC Building
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End of Part - II