2018 Scienceline Publication

Journal of Civil Engineering and Urbanism

Volume 8, Issue 1: 01-05; Jan 25, 2018

ISSN-2252-

0430

Studies on Regular and Irregular Tall Structures

Subjected to Earthquake Loading

Miss Chaya1 and Naveen GM2

1Assistant Professor, Department of Civil Engineering, EIT, Chamarajanagar-571313, Karnataka 571313, India 2Assistant Professor, Department of Civil Engineering, Government .Engineering College, Chamarajanagara-571313, Karnataka 571313, India

Corresponding author’s E-mail: naveengm.gowda@gmail.com

ABSTRACT: Multi storey buildings are constructed by Reinforced concrete are subjected to earthquake forces are affected dangerously, they get failure during earthquake. The main reason for this failure is that the irregularity in building structures. In this paper study is made to find the response of regular and irregular building structures having plan irregularity located in seismic zone V. In this present study O

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R

A

R

I

Analysis has been made by taking 10 storey building by Response Spectrum Method using ETABS 2015

I

c

e

:

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c

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and code IS 1893:2002 (part 1). Analysis is carried out for Regular and Irregular buildings at a height of e

e

2

p

i

t

v

2

I

e

e

5

N

35.5 m in zone V. Behavior of structures are comparing the responses in the form of maximum storey d

d

2

A

3 0

2

4

L

displacement, storey drift, storey stiffness, periods and frequencies of modes during earthquake.

0

8

3

D O 0

A

1

Presently there are four models. One is Regular structure and remaining are Irregular structural models, e

c

8

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t

.

.

0

2

2

0

T

all models have different shape but having same area. An attempt is made to study the Response of 0

0

0

I

1

1

0

C

7

7

1

building structures with respect to the loads and their combinations. The results comparison is made by

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8

E

taking maximum load combinations considering the primary loads (LL, DL, WL, and EQL). Totally four Configuration models are considered for the analysis.

Keywords: Horizontal irregularity, Earthquake load, Storey shear, Maximum storey displacement, Maximum storey drift.

INTRODUCTION

ground motions. When the ground motions are occurred,

the structures are affected in three dimensions in the

Structure is subjected to seismic forces during

three directions, one is vertical direction (Z) and other

earthquake, structures undergo displacements at the base

two are horizontal directions (X, Y) .The structure is

and the components of the structure are also get

mostly affected by the horizontal direction of vibrations.

displaced and damaged during the earthquake (Agarwal

All the structures are designed to satisfy the gravity

and Shrikande, 2011; Duggal, 2007). During earthquake

loads acted in vertical direction. In the design

seismic forces are developed, Structure is experienced

specifications safety factors are to be considered,

there seismic forces. Seismic forces developed the

because of this most of the structure are tended to be

seismic waves and a wave reaches the structure during

adequately protected against vertical shaking. But its

earthquake. The waves generated from the earthquake

affects should be considered in design of the reinforced

epicenter disturb the structure during earthquake. They

concrete (R.C.C) structures. When we are considering

can produce ground motions in the structure. Earthquake

design of building by considering vertical ground

is the natural phenomenon; it is the Rapid movement of

motions is not safe. It is to be considering the horizontal

the earth surface taking place at or below the surface of

displacement of the building. Generally, forces acted in

the earth. When the earthquake takes place the layers of

the horizontal ground motions of the earthquake are

the soil in the earth also displace the structure

taken important for the design of the structures.

components of the building are get vibrated by this

To cite this paper: Chaya M and Naveen GM (2018). Studies on Regular and Irregular Tall Structures Subjected to Earthquake Loading. J. Civil Eng. Urban., 8 (1): 01-05.

www.ojceu.ir

1

Therefore the building structures must be designed to

Table 1. Parameters considered for the building design

resist the horizontal forces acted due to the earthquake.

Parameter

Type\Value

Structure Type

RCC Building Structure

Objectives of the study

Number of Stories

10

•

This study focus is on the behavior of

Bottom Storey Height(Basement)

4m

structures during earthquake having

Storey’s Height(Ground+

3.5m

irregularities in plan and having same area.

Floors)

•

To study the parameters of storey

Regular , Irregular Building

Type of Structure

Structure

shear, storey displacements, maximum storey

Area of Structure

1600 m2

drift of all models during earthquake.

Bay Width in both direction

5m

•

To study the frequencies and periods in

Beam Size

0.2mX0.45m

Grade of Concrete

M20

different modes.

Column Size

0.3mX0.9m

Grade of Concrete

M25

Thickness of Slab

0.12m

MATERIALS AND METHODS

Concrete Brick Thickness

0.2m

Live Load

4 KN\m2

Model of the structures

Seismic Zone

V ( Z=0.36 )

Parameters consider. In the present study

Importance Factor

1.5

Response Reduction Factor

5

four different buildings are considered, one is

Soil Type

II

horizontal regular and other three are irregular

buildings. Buildings are modelled using ETABS

Analysis of the structures

package and analysed (Prashanth et al., 2012).

Following models are analyzed as special

The properties of the considered building

moment resisting frame using response

configurations in the present study are

spectrum analysis.

summarized below.

Figure 1. Plan and 3d view of model 1

To cite this paper: Chaya M and Naveen GM (2018). Studies on Regular and Irregular Tall Structures Subjected to Earthquake Loading. J. Civil Eng. Urban., 8 (1): 01-05.

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Figure 2. Plan and 3d view of model 2

Figure 3. Plan and 3d view of model 3

Figure 4. Plan and 3d view of model 4

Load combinations

The results are presented by plotting the graph for

Analysis is done for all the loads of 20

each models considered in the study. The analysis

combinations by using ETABS, out of which the critical

carried out by the Response spectrum analysis. The

load combination is, (1.2DL+1.2LL+1.2EQY)

result of periods and frequencies, maximum storey drift,

storey maximum displacements, storey shear is

RESULTS AND DISCUSION

presented for all models. In this study regular building is

To cite this paper: Chaya M and Naveen GM (2018). Studies on Regular and Irregular Tall Structures Subjected to Earthquake Loading. J. Civil Eng. Urban., 8 (1): 01-05.

www.ojceu.ir

3

compared with irregular building; the performance of the

models is observed in high seismic zone V.

Figure 5 shows the variation of models for different

periods in different number of modes. It is observed that

the periods of vibrations are decreases with increases in

number of modes. Model 1 has greater period of

vibration as compared to other models.

From the figure 6 it is observed that frequency is

increases with increases in modes number. In the

beginning of the vibrations the frequency is more in

model 4 (Irregular building) and the ending frequency is

greater in model 3.

The figure 7 shows the variation in the storey drift.

It is less in storey 1 and increases up to storey 3, after 3

Figure 5. Variation of periods

storeys it is decreases up to last storey.

In this figure 8 it is observed that storey

Table 3. Frequencies of models in cycles per seconds

displacement is increases with increases in the number

Mode No

Model 1

Model 2

Model 3

Model 4

of storey. From the table model 2, 3, 4 (irregular

1

0.358

0.361

0.362

0.364

buildings) have similar displacement. Model 1 has

2

0.452

0.444

0.477

0.439

greater displacements.

3

0.468

0.469

0.486

0.474

In figure 9 storey shear increases with decrease in

4

1.094

1.105

1.109

1.112

number of stories. Storey shear is maximum in Irregular

5

1.458

1.44

1.565

1.432

building structure. Model 3 has greater storey shear.

6

1.555

1.562

1.622

1.582

Shear force is greatly affected the base.

7

1.888

1.909

1.925

1.923

8

2.73

2.716

2.822

2.725

 Periods of modes of vibration

9

2.755

2.788

3.008

2.812

 Frequencies of all models

10

3.039

3.063

3.18

3.105

 Maximum storey drift of all models of (1.2DL +

11

3.704

3.751

3.813

3.787

1.2LL + 1.2EQY)

12

4.354

4.359

4.88

4.401

 Storey displacement in (1.2DL + 1.2LL + 1.2EQY)

 Storey shear in kn of all models in (1.2DL + 1.2LL

+ 1.2EQY)

 Storey shear in kn of all models in

(1.2DL+1.2LL+1.2EQY)

Table 2. Periods of modes of vibration in seconds

Mode no

Model 1

Model 2

Model 3

Model 4

1

2.794

2.767

2.763

2.751

2

2.212

2.251

2.098

2.277

3

2.139

2.133

2.056

2.11

4

0.914

0.905

0.902

0.899

5

0.686

0.695

0.639

0.699

6

0.643

0.64

0.617

0.632

7

0.53

0.524

0.52

0.52

Figure 6: Frequencies of vibrations

8

0.366

0.368

0.354

0.367

Table 4. Maximum storey drift of all models of

9

0.363

0.359

0.332

0.356

(1.2dl+1.2ll+1.2eqy)

10

0.329

0.327

0.315

0.322

Storey

Model 1

Model 2

Model 3

Model 4

11

0.27

0.267

0.262

0.264

10

0.000935

0.000932

0.000976

0.000938

12

0.23

0.229

0.205

0.227

9

0.00176

0.001749

0.001781

0.001747

8

0.002506

0.002487

0.002516

0.002481

7

0.003093

0.003068

0.003096

0.003058

6

0.003529

0.0035

0.003526

0.003488

5

0.003835

0.003803

0.003826

0.003788

4

0.004031

0.003997

0.004016

0.00398

3

0.004128

0.004091

0.004101

0.004072

2

0.004066

0.004024

0.004012

0.004001

1

0.002968

0.002925

0.002844

0.002888

To cite this paper: Chaya M and Naveen GM (2018). Studies on Regular and Irregular Tall Structures Subjected to Earthquake Loading. J. Civil Eng. Urban., 8 (1): 01-05.

www.ojceu.ir

4

0

-4807

-4942

-5137

-5041

Figure 7. Maximum storey drift

Table 5. Storey displacement in mm

Figure 9. Storey shear along number of stories

(1.2dl+1.2ll+1.2eqy)

CONCLUSION

Storey

Model 1

Model 2

Model 3

Model 4

10

109.5

108.5

108.9

108

1. In general it is observed that period of modes of

9

106.2

105.2

105.4

104.7

vibrations decreases with increase in number of mode.

8

100

99.1

99.2

98.6

Model 1 has greater period of vibration.

7

91.3

90.4

90.4

89.9

2. Frequencies of modes increase with increasing in

6

80.4

79.7

79.6

79.2

number of modes. Model 3 has greater frequency.

5

68.1

67.4

67.2

67

3. Maximum storey drift is less in bottom storey,

4

54.7

54.1

53.8

53.7

after bottom storey that it increases with increase in up

3

40.5

40.1

39.8

39.8

to storey 7 again it is decreases.

2

26.1

25.8

25.4

25.6

4. Storey displacement increases with increases in

1

11.9

11.7

11.4

11.6

storey height. Displacement is greater in regular

0

0

0

0

0

building.

5. Storey shear increases with decreases in number

of storey and shear is maximum at the base of the

building. Storey shear is maximum in model 3.

6. Considering the above conclusion results we

conclude that plan asymmetry like horizontal irregularity

has slight differences in results of all parameters.

Author’s contribution

All authors contributed equally to this work.

Competing interests

The Authors declare that they have no competing

interests

Figure 8. Variation of displacement of stories

Table 6. Storey shear of all models in kN

REFERENCES

(1.2dl+1.2ll+1.2eqy)

Storey

Model 1

Model 2

Model 3

Model 4

Konakalla R, Dutt chilakapati R, Babu Raparla H

(2014). Effect of vertical irregularity in multi-

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weight Ferrocement Beam under Monotonic

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(JOSE), Vol. 39, No.4.

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To cite this paper: Chaya M and Naveen GM (2018). Studies on Regular and Irregular Tall Structures Subjected to Earthquake Loading. J. Civil Eng. Urban., 8 (1): 01-05.

www.ojceu.ir

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Bagheri B, Salimi Firoozabad E and Yahyaei M (2012).

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Analysis of Multistorey Irregular Building.

International Journal of Civil, Environmental,

Structural Construction and Architectural

Engineering, Vol.6, No.11.

Naveen GM and Suresh GS (2015). Experimental Study

on the Ductile Characteristics of Light Weight

Ferrocement Beams under Monotonic and

Repeated Loading. International Journal of

Innovative Research in Science, Engineering and

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Agarwal P and Shrikande M (2011). Earthquake

Resistant Design of Structures. Prentice Hall of

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Structures, Oxford University Press. - Technology

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BIOGRAPHIES

Dr. Naveen G M, is working as Assistant

Professor in Government Engineering College

Chamarajanagara, Karanataka, India-571313, received

his BE degree from UBDT college Davangere; M.Tech

in MCE, Hassan and PhD at National Institute of

Engineering, Mysore under VTU. Research interests

include the Reinforced Concrete Structure and steel

structure Analysis and design in civil structures.

Miss. Chaya S, assistant professor of civil

engineering Department, EIT Chamarajanagar, have an

experience in teaching and research in structural

Engineering field. Research interests include the

Reinforced Concrete Structure design in civil structures.

To cite this paper: Chaya M and Naveen GM (2018). Studies on Regular and Irregular Tall Structures Subjected to Earthquake Loading. J. Civil Eng. Urban., 8 (1): 01-05.

www.ojceu.ir

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