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 Chaya^{1 }and Naveen GM^{2 }

571313, India

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

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

2015 and code IS 1893:2002 (part 1). Analysis is carried out for Regular and Irregular buildings at a

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

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

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

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

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

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

the ground motions are occurred, the structures are

affected in three dimensions in the three directions, one is

vertical direction (Z) and other two are horizontal

directions (X, Y) .The structure is mostly affected by the

horizontal direction of vibrations. All the structures are

designed to satisfy the gravity loads acted in vertical

direction. In the design specifications safety factors are to

be considered, because of this most of the structure are

tended to be adequately protected against vertical shaking.

But its affects should be considered in design of the

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

considering design of building by considering vertical

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

horizontal displacement of the building. Generally, forces

acted in the horizontal ground motions of the earthquake

are taken important for the design of the structures.

Therefore the building structures must be designed to

resist the horizontal forces acted due to the earthquake.

Structure is subjected to seismic forces during earthquake,

structures undergo displacements at the base and the

components of the structure are also get displaced and

damaged during the earthquake (Agarwal and Shrikande,

2011; Duggal, 2007). During earthquake seismic forces

are developed, Structure is experienced there seismic

forces. Seismic forces developed the seismic waves and a

wave reaches the structure during earthquake. The waves

generated from the earthquake epicenter disturb the

structure during earthquake. They can produce ground

motions in the structure. Earthquake is the natural

phenomenon; it is the Rapid movement of the earth

surface taking place at or below the surface of the earth.

When the earthquake takes place the layers of the soil in

the earth also displace the structure components of the

building are get vibrated by this ground motions. When

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.

1

Table 1. Parameters considered for the building design

Objectives of the study

• This study focus is on the behavior of structures

during earthquake having irregularities in plan and having

same area.

Parameter

Type\Value

Structure Type

Number of Stories

RCC Building Structure

10

• To study the parameters of storey shear, storey

displacements, maximum storey drift of all models during

earthquake.

• To study the frequencies and periods in different

modes.

Bottom Storey Height(Basement)

4m

Storey’s Height(Ground+ Floors)

3.5m

Regular , Irregular Building

Type of Structure

Structure

1600 m^{2 }

5m

0.2mX0.45m

M_{20 }

Area of Structure

Bay Width in both direction

Beam Size

Grade of Concrete

Column Size

Grade of Concrete

Thickness of Slab

0.3mX0.9m

M_{25 }

0.12m

MATERIALS AND METHODS

Concrete Brick Thickness

0.2m

4 KN\m^{2 }

Model of the structures

Live Load

Parameters consider. In the present study four

different buildings are considered, one is horizontal

regular and other three are irregular buildings. Buildings

are modelled using ETABS package and analysed

(Prashanth et al., 2012). The properties of the considered

building configurations in the present study are

summarized below.

Seismic Zone

V ( Z=0.36 )

1.5

5

Importance Factor

Response Reduction Factor

Soil Type

II

Analysis of the structures

Following models are analyzed as special moment

resisting frame using response spectrum analysis.

Figure 1. Plan and 3d view of model 1

Figure 2. Plan and 3d view of model 2

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.

2

Figure 3. Plan and 3d view of model 3

Figure 4. Plan and 3d view of model 4

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

storeys it is decreases up to last storey.

Load combinations

Analysis is done for all the loads of 20 combinations

by using ETABS, out of which the critical load

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

In this figure

displacement is increases with increases in the number of

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

8 it is observed that storey

RESULTS AND DISCUSION

The results are presented by plotting the graph for

each models considered in the study. The analysis carried

out by the Response spectrum analysis. The result of

periods and frequencies, maximum storey drift, storey

maximum displacements, storey shear is presented for all

models. In this study regular building is 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.

have similar displacement. Model

displacements.

In figure 9 storey shear increases with decrease in

number of stories. Storey shear is maximum in Irregular

building structure. Model 3 has greater storey shear. Shear

force is greatly affected the base.

1

has greater

Periods of modes of vibration

Frequencies of all models

Maximum storey drift of all models of (1.2DL +

1.2LL + 1.2EQY)

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

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

1.2EQY)

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

Storey shear in kn of all models in

(1.2DL+1.2LL+1.2EQY)

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.

3

Table 2. Periods of modes of vibration in seconds

Table 4. Maximum storey drift of all models of

(1.2dl+1.2ll+1.2eqy)

Mode no

Model 1

2.794

2.212

2.139

0.914

0.686

0.643

0.53

Model 2

2.767

2.251

2.133

0.905

0.695

0.64

Model 3

2.763

2.098

2.056

0.902

0.639

0.617

0.52

Model 4

2.751

2.277

2.11

Storey

Model 1

0.000935

0.00176

Model 2

0.000932

0.001749

0.002487

0.003068

0.0035

Model 3

0.000976

0.001781

0.002516

0.003096

0.003526

0.003826

0.004016

0.004101

0.004012

0.002844

Model 4

0.000938

0.001747

0.002481

0.003058

0.003488

0.003788

0.00398

1

10

9

2

3

8

0.002506

0.003093

0.003529

0.003835

0.004031

0.004128

0.004066

0.002968

4

0.899

0.699

0.632

0.52

7

5

6

6

5

0.003803

0.003997

0.004091

0.004024

0.002925

7

0.524

0.368

0.359

0.327

0.267

0.229

4

8

0.366

0.363

0.329

0.27

0.354

0.332

0.315

0.262

0.205

0.367

0.356

0.322

0.264

0.227

3

0.004072

0.004001

0.002888

9

2

10

11

12

1

0.23

Figure 7. Maximum storey drift

Figure 5. Variation of periods

Table 3. Frequencies of models in cycles per seconds

Table 5. Storey displacement in mm (1.2dl+1.2ll+1.2eqy)

Mode No

Model 1

0.358

0.452

0.468

1.094

1.458

1.555

1.888

2.73

Model 2

0.361

0.444

0.469

1.105

1.44

Model 3

0.362

0.477

0.486

1.109

1.565

1.622

1.925

2.822

3.008

3.18

Model 4

0.364

0.439

0.474

1.112

1.432

1.582

1.923

2.725

2.812

3.105

3.787

4.401

Storey

Model 1

109.5

106.2

100

Model 2

108.5

105.2

99.1

90.4

79.7

67.4

54.1

40.1

25.8

11.7

0

Model 3

108.9

105.4

99.2

90.4

79.6

67.2

53.8

39.8

25.4

11.4

0

Model 4

108

1

10

9

8

7

6

5

4

3

2

1

0

2

104.7

98.6

89.9

79.2

67

3

4

91.3

80.4

68.1

54.7

40.5

26.1

11.9

0

5

6

1.562

1.909

2.716

2.788

3.063

3.751

4.359

7

53.7

39.8

25.6

11.6

0

8

9

2.755

3.039

3.704

4.354

10

11

12

3.813

4.88

Figure 8. Variation of displacement of stories

Figure 6: Frequencies of vibrations

4

Table 6. Storey shear of all models in kN

REFERENCES

(1.2dl+1.2ll+1.2eqy)

Konakalla R, Dutt chilakapati R, Babu Raparla H (2014).

Effect of vertical irregularity in multi-storied

buildings under dynamic loads using linear static

Analysis. International Journal of Education and

Applied Research (IJEAR). Vol. 4, Issue SPL-2.

Naveen GM and Suresh GS (2012). Behaviour of Light

weight Ferrocement Beam under Monotonic Flexural

loading. Journal of Structural Engineering (JOSE),

Vol. 39, No.4.

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

Comparative Study of the static and Dynamic

Analysis of Multistorey Irregular Building.

International Journal of Civil, Environmental,

Storey

Model 1

Model 2

Model 3

Model 4

10

9

8

7

6

5

4

3

2

1

0

-914.154

-2006

-2872

-3538

-4031

-4377

-4601

-4730

-4790

-4790

-4807

-939.558

-2062

-2953

-3638

-4144

-4500

-4730

-4863

-4924

-4942

-4942

-974.938

-2142

-3068

-3780

-4307

-4677

-4916

-5054

-5118

-5137

-5137

-957.66

-2103

-3012

-3711

-4228

-4590

-4825

-4961

-5023

-5041

-5041

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 Technology,

Vol. 4, No.3.

Agarwal P and Shrikande M (2011). Earthquake Resistant

Design of Structures. Prentice Hall of India Private

Limited, New Delhi, India

Duggal SK (2007). Earthquake Resistant Design of

Structures, Oxford University Press. - Technology &

Engineering, 448 pages.

Prashanth P, Anshuman S, Pandey RK, Herbert A (2012)

Comparision of design Results of a structure

designed using STAAD and ETABS software's.

International Journal of Civil And Structural

Engineering. Vol.2, No.3.

Figure 9. Storey shear along number of stories

CONCLUSION

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

vibrations decreases with increase in number of mode.

Model 1 has greater period of vibration.

2. Frequencies of modes increase with increasing in

number of modes. Model 3 has greater frequency.

3. Maximum storey drift is less in bottom storey,

after bottom storey that it increases with increase in up to

storey 7 again it is decreases.

4. Storey displacement increases with increases in

storey height. Displacement is greater in regular 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.

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.

Author’s contribution

All authors contributed equally to this work.

Miss. Chaya S, assistant professor of civil

Competing interests

The Authors declare that they have no competing

interests

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.

5