seismic analysis of multi storied rc buildings- part 2

8/13/2019 Seismic Analysis of Multi Storied RC Buildings- Part 2

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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



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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



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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)


(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)



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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)


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)



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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



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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

*=



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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



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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



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The forces are applied and analysed



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The forces are applied



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End of Part - II

seismic analysis of multi storied rc buildings- part 2

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