International Journal of Applied Engineering Research ISSN ... fileIII. MODELLING AND ANALYSIS For this project total 9 models are to be studied. The modelling is done by using ETABS

Study on Seismic Performance of Multistoried building with

Oblique Columns

Geethu Krishna K V M. Tech student, Department of Civil Engineering

Vimal Jyothi engineering college, Chemperi Kannur, Kerala, India

Lekshmi L Assistant Professor, Department of Civil Engineering

Vimal Jyothi engineering college, Chemperi Kannur, Kerala, India

Abstract— The increased number of multi-storied

buildings is the strength of a country in the economical and

technical aspect. Nowadays various construction techniques are

adopted in order to increase the seismic performance of the

building. Here the new method is to use the oblique columns

instead of normal columns. Oblique columns are columns at an

angle to the specified line. Before adopting this technique it is

necessary to study it detail and find the performance of such

building under the action of seismic loading. This project is an

attempt to study the performance of building having oblique

columns of different angles and to compare different

parameters by response spectrum analysis using ETABS

software.

Keywords—oblique columns, ETABS, response spectrum

analysis

I. INTRODUCTION

The new construction method to increase the seismic performance of the multi-storied buildings is the use of oblique columns instead of normal columns. Oblique column is a column which is not constructed vertical. The oblique columns can be adopted in high-rise, mid-rise and low-rise building. The position, arrangement, and angle of the inclined columns are makes different types oblique columns in buildings. The angle may vary and this affects the performance of the building. For oblique column of below 900, there will be a decrease in plan dimensions and for above 900, there will be increase in plan dimensions as we reach upper floors. It affects the lateral stiffness of the buildings. But the seismic responses may vary in each case.

The dynamic analysis is done to quantify the storey responses in each type of buildings. Here, ETABS software is used for the response spectrum analysis. It is a complex structural analysis package. It can be used for the analysis and design of buildings and its components.

This project focuses on the seismic performance of the building with oblique columns in different angles and to know how much variations are there in different parameters like storey displacement, storey stiffness, storey shear etc. from the conventional reinforced concrete building with normal columns. If this method is better with more seismic performance this will help to make multi-storied buildings with fewer damages in place of normal construction.

A. Objectives

To compare the seismic performance of a low-rise, mid-rise, high-rise building with normal and oblique column by response spectrum analysis

To study the seismic performance of oblique columns with different angles in low, mid and high-rise buildings.

B. Need for Study

Sophisticated construction industry is rapidly increasing due to the developments and demands for population. The new idea is that the columns are not vertical. We can build multi-storied building buildings with oblique columns. But the seismic performance should be studied to know whether these new construction techniques adaptable or not. Because, the performance of the high-rise, mid-rise and low-rise building will be different from each other for different angles under seismic loading. So it is very important to study the seismic performance for different types of building and also compare with the conventional method of construction. If it is replaceable for the normal constructions and with more advantages, it will be a revolutionary change in civil engineering world

II. OBLIQUE COLUMN

In recent years, many buildings are constructed in irregular structure system with inclined columns. It effects on the structural behaviour of the joints. The Oblique Column is the column, which neither parallel nor at right angles to a specified line means they are slanted or rotated at an angle. Since the external loads leads to shear and flexural forces on the inclined column, the performance of the building is differs from the conventional method of construction. Oblique columns are stiffer as RC frames, and therefore, the initial stiffness of the RC frames largely depends upon the stiffness of oblique column. Fig. 1 is the example for a high-rise building with oblique columns.

Fig. 1 High-rise Building with Oblique columns

International Journal of Applied Engineering Research ISSN 0973-4562 Volume 14, Number 12, 2019 (Special Issue) © Research India Publications. http://www.ripublication.com

Page 186 of 190

III. MODELLING AND ANALYSIS

For this project total 9 models are to be studied. The modelling is done by using ETABS software. The buildings are modelled with concrete structural elements. The details are given below and in Table 1 & 2. High-rise building – G+19 Stories Mid –rise building – G+9 stories Low-rise building – G+3 stories

TABLE 1. MODEL DESCRIPTION

Sl. No. Model Name Description

1 H80 High-rise building with oblique columns of 800

2 H85 High-rise building with oblique columns of 850

3 H90 High-rise building with normal columns of 900

4 M80 Mid-rise building with oblique columns of 800

5 M85 Mid-rise building with oblique columns of 850

6 M90 Mid-rise building with normal columns of 900

7 L80 Low-rise building with oblique columns of 800

8 L85 Low-rise building with oblique columns of 850

9 L90 Low-rise building with normal

columns of 900

TABLE 2. PRELIMINARY DATA

Seismic zone III

Seismic zone factor 0.16 (As per IS 1893-2002)

Number of stories G+19, G+9, G+3

Floor height 3 m

Depth of slab 200 mm

Size of beam for G+19 and G+9 350 x 650 mm

Size of beam for G+3 300 x 600 mm

Size of columns 750 x 750 mm

Spacing between frames in x

direction

8 m

Spacing between frames in y

direction

8 m

Materials M30 concrete , Fe500 steel

Support condition Fixed support

Soil type Zone -II

Thickness of wall 230 mm

Dead load 1 kN/m2

Live load 3 kN/m2

A. Models Created

The high-rise buildings with oblique column at different angles such as 800 ,850 and 900 are shown in Fig. 2, Fig.3 and Fig. 4

IV. RESULTS

The results are taken after the response spectrum analysis. The storey response of model H80 in x and y direction is graphically shown below in Fig.5, 6, 7 and 8

Fig. 2 H80 Fig. 3 H85

Fig. 4 H90

Fig. 5.Storey Displacement of H80


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A. Maximum Storey Displacement

Maximum storey displacement of each model is tabulated in the Table.3. and the graph shown in Fig.8

TABLE 3. MAXIMUM STOREY DISPLACEMENT

Model Name Maximum Storey Displacement( mm)

H80 17.127

H85 21.892

H90 29.845

M80 21.474

M85 23.577

M90 23.768

L80 11.049

L85 17.559

L90 21.373

Fig. 9. Maximum Storey Displacement

Here, the displacement is maximum for H90. In mid-rise building, the displacement is somewhat similar in oblique and normal building. In low-rise building, the displacement is less in buildings with oblique column. It is smaller when the angle is at 800.

B. Maximum Storey Drift

The value of maximum drift in each model is shown in the Table 4 and depicted in Fig. 10. Among high-rise buildings, the drift is maximum for normal column construction compared to oblique column buildings. The drift is more when the angle is 850 than 800

TABLE 4. MAXIMUM STOREY DRIFTT

Model Name Maximum Storey Drift (unit less)

H80 0.000756

H85 0.000921

H90 0.000973

M80 0.000376

M85 0.000567

M90 0.000768

L80 0.000269

L85 0.000438

L90 0.000695

Fig. 6. Storey Drift of H80

Fig. 7. Storey Shear of H80

Fig. 8. Storey Stiffness of H80

05

101520253035

H80 H85 H90 M80 M85 M90 L80 L85 L90

Maximum StoreyDisplacement( mm)


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Fig. 10. Maximum Storey Drift

C. Maximum Storey Shear

The maximum storey shear in all models is given in Table 5. Comparison of maximum storey shear in different models is shown in Fig. 11. Clearly, the shear decreases when the angle of the column becomes acute. In all cases, shear minimum for 800 and more for an angle 900

TABLE 5. MAXIMUM STOREY SHEAR

Model Name Maximum Storey Shear (kN)

H80 1234.688

H85 1492.382

H90 1767.506

M80 912.083

M85 1306.482

M90 1379.593

L80 553.011

L85 584.101

L90 732.948

Fig. 11. Maximum Storey Shear

D. Maximum Storey Stiffness

The maximum storey stiffness for various models are given in Table 6 and shown graphically in Fig. 12. The stiffness is greatly increased when the oblique column construction is adopted. It is more when the angle of columns is 800. In low-rise building the stiffness is similar for both the angle 800 and 900. In mid-rise building, the stiffness is reduced gradually when the angle increases.

TABLE 6. MAXIMUM STOREY STIFFNESS

Model Name Maximum Storey Stiffness (kN /m)

H80 2038474

H85 1949542

H90 816554

M80 1312964

M85 1170572

M90 865591

L80 783867

L85 762575

L90 89170

Fig. 12. Maximum Storey Drift

V. CONCLUSIONS In all cases, the storey displacement is decreases when the

angle of column is decreases. In high-rise building, the storey displacement is 40% lesser

for 800 columns and 27% lesser for 850 column than the normal column.

In low-rise building, the displacement for 800 and 850 columns are about 48% and 18% respectively compared to normal column construction.

The storey drift increases when the angle of oblique column increases

In the low-rise building, the drift is reduced 24% for 800 and 850 respectively than 90o columns.

The storey shear decreases when the column angle decreases than 900. In mid-rise building, when the column is at 800, the storey shear decreased about 34% than the normal column.

In high-rise, mid-rise and low-rise buildings, the stiffness is increased when the angle of column decreased.

By the use of 800 oblique columns, the stiffness is increased 60% in high-rise, 34% in mid-rise and 89% in low-rise buildings than the normal column having 900.

The overall seismic performance is increased when the oblique columns are used for construction.

REFERENCES

[1] Kai Hu, Yimeng Yang , Suifeng Mu and Ge Qu ,“Study on High-rise Structure with Oblique Columns by ETABS, SAP2000, MIDAS/GEN and SATWE”, Science Direct, Vol 31 pp- 474 – 480 , April 2012.

[2] Kona Narayana Reddy, Dr.E.Arunakanthi , “A Study on Multi-Storeyed Building with Oblique Columns by using ETAB”, International Journal of Innovative Research in Science,Engineering and Technology, vol. 210 pp.320–325, April 2017.

0

0.0002

0.0004

0.0006

0.0008

0.001

0.0012

H80 H85 H90 M80 M85 M90 L80 L85 L90

Maximum Storey Drift(unit less)

0

500

1000

1500

2000

H80 H85 H90 M80 M85 M90 L80 L85 L90

Maximum StoreyShear (kN)

0

500000

1000000

1500000

2000000

2500000

H80 H85 H90 M80 M85 M90 L80 L85 L90

Maximum Storey Stiffness(kN /m)


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[3] Girish kumar G.M, S M Maheswarappa, “Seismic Performance Study of Multistoried Buildings with Oblique Columns by using ETABS”, International Journal of Engineering Research and Advanced Technology (IRERAT), Volume: 04 Issue: 08, p-ISSN: 2454-6135, January 2017.

[4] Vivek Narayanan , Aiswarya S, “Effect Of Oblique Column And Viscous Damper On Podium Structure Using Etabs”, International Research Journal of Engineering and Technology ( IRJET), volume 04, Issue 05, ISSN: 2395 -0056, March 2016.

[5] Shahana E, Aswathy S Kumar , “Comparative Study of Diagrid Structures with and without Corner Columns”, International Journal of Science and Research (IJSR), volume:05 Issue7 ISSN:239-7064, June 2016.

[6] KK Pathak, Ashish Mohan Shivhare, and S K Dubey , “Parametric Seismic Analysis of Tall Buildings with Different Geometry and Constant Plan Area”, Volume No.02, November 2016.


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Documents

International Journal of Applied Engineering Research ISSN ... fileIII. MODELLING AND ANALYSIS For this project total 9 models are to be studied. The modelling is done by using ETABS