COMPARATIVE STUDY OF OUTRIGGER STRUCTURE WITH DIFFERENT CONFIGURATIONS

PREPARED BY

JUGAL S. SENGHANI

Str. Design Engineer at Post Tension Services India

Pvt. Ltd., Vadodara.

GUIDED BY

MS. POOJA MISTRY

Assistant Professor at Government Engineering

College, Bharuch.

2ND AND 3RD SEPT. 2017

3333rd NATIONAL CONVENTION OF CIVIL ENGINEERS NATIONAL CONVENTION OF CIVIL ENGINEERS INSTITUTION OF ENGINEERS (I)INSTITUTION OF ENGINEERS (I)

GUJARAT STATE CENTRE,AHMEDABAD. GUJARAT STATE CENTRE,AHMEDABAD.

PRESENTED BY

NILESH V PRAJAPATI Designs (R&B) circle,

Roads & Building Department, Gandhinagar.

PRESENTATION OUTLINES…PRESENTATION OUTLINES…INTRODUCTION

BACKGROUND

BENEFITS OF OUTRIGGER SYSTEM

OBJECTIVE OF PRESENT STUDY

ANALYSIS AND GRAPHICAL REPRESENTATION

CONCLUSION

REFERENCES

INTRODUCTIONINTRODUCTION

• What is outrigger?

Outrigger is a connecting and tying member between two structural member, which is

generally core of building and peripheral columns.

The outrigger system typically engages the core with columns to increase the lateral

stability and stiffness of a building.

It is also defined as a, rigid horizontal structural members to improve building

overturning stiffness and strength by connecting the building core to a peripheral

columns.

• The explanation of building outrigger behaviour is simple because outriggers act as

stiff arms engaging outer columns, when a central core tries to tilt, its rotation at the

outrigger level induces a tension- compression couple in the outer columns acting in

opposition to that movement.

• The result is a types of restoring moment acting on the core at that level.

• Analysis and design of a complete core-and-outrigger system is not that simple,

distribution of forces between the core and outrigger system depends on the relative

stiffness of each element.

BACKGROUNDBACKGROUND

• Outrigger have been used in tall, narrow building for nearly half a century, but the

design principle has been used for millennium.

• The oldest “outrigger” are horizontal beams connecting the main canoe-shaped hulls of

Polynesian oceangoing boats to outer stabilizing floats.

• A narrow boats hull can overturn when tossed by unexpected waves, but small amount

of upward resistance or weight (downward resistance) acting through outrigger

leverage is sufficient to avoid overturning. Same phenomenon we can apply to the

building by connecting the core and perimeter columns.

BENEFITS OF OUTRIGGER BENEFITS OF OUTRIGGER SYSTEMSYSTEM

• Reduction in deformation of building.

• Reduction in storey drift.

• It increases the lateral stability of structure.

• Force reduction at core foundation.

OBJECTIVE OF PRESENT OBJECTIVE OF PRESENT STUDYSTUDY

• To minimize the lateral displacement of high-rise RC building.

• To finding out the optimum location of Outrigger structural system for high-rise RC

building to resist the seismic load and wind load.

• For combining the strength of outrigger system and shear wall system to withstand the

lateral load.

• To increase the stability of structure by tying the two main structural elements.

STUDY MODELSTUDY MODEL

Types of models for 30 storey building

•Type of models with shear wall and outrigger-belt truss at different positions

Plan view of bare frame

STUDY MODELSTUDY MODEL

Plan view of Shear Wall at centre +corner

STUDY MODELSTUDY MODEL

STUDY MODELSTUDY MODEL

View of Structure with outrigger at 20th storey

COMPARISON TOP STOREY DISPLACEMENT BETWEEN STRUCTURE WITH AND WITHOUT OUTRIGGER FOR 30 STOREY BUILDING.

Type of structure

Top Storey Displacement (mm)

At 10th storey At 20th storey At 30th storey

Bare frame 134 283.2 370.2

SW at core 98.6 222.4 310.5

SW at core + corner 66.1 170.4 262.3

RCC Outrigger at 10th storey 78.8 185 277.1

RCC Outrigger at 20th storey 100.1 203.6 270.8

RCC Outrigger at 30th storey 99.4 223 297.1

Results and Discussion Results and Discussion

GRAPHICAL REPRESENTATION OF STOREY DISPLACEMENT

Continue…

Graphical representation of Top Storey Displacement

Continue…

Continue… Graphical representation of Storey Drift Ratio

Comparison of Base Shear

Continue…

Base Shear

Bare frame SW at coreSW at core+

corner

RCC

Outrigger at

10th

RCC

Outrigger at

20th

RCC

Outrigger at

30th

X-Dir

kN

X-Dir

kN

X-Dir

kN

X-Dir

kN

X-Dir

kN

X-Dir

kN

Base Shear 12134.65 13545.78 17652.09 14182.55 13856.14 13953.91

Weight 413091.7 418132.6 438265.1 419819.5 419819.5 419819.5

Graphical representation of Base Shear

Continue…

COMPARISON BETWEEN STRUCTURE WITH RCC AND STEEL OUTRIGGER FOR 30 STOREY BUILDING.

Storey

RCC Outrigger

at 10th

RCC

Outrigger at

20th

RCC

Outrigger at

30th

Steel

Outrigger a

10th

Steel

Outrigger at

20th

Steel

Outrigger at

30th

X-Dir

mm

X-Dir

mm

X-Dir

mm

X-Dir

mm

X-Dir

mm

X-Dir

mm

Storey 10 78.8 100.1 99.4 82.9 98.4 99

Storey 20 185 203.6 223 192.3 205.3 222.1

Storey 30 277.1 270.8 297.1 281.9 277.1 297.9

Comparison of Top Storey Displacement

Continue… Graphical representation of Storey Displacement

Continue… Graphical representation of Storey Displacement

Continue… Graphical representation of Top Storey

Displacement

Continue… Graphical representation of Top Storey Displacement

Comparison of Base Shear

Continue…

RCC

Outrigger at

10th

RCC

Outrigger at

20th

RCC

Outrigger at

30th

Steel

Outrigger at

10th

Steel

Outrigger at

20th

Steel

Outrigger at

30th

X-Dir

kN

X-Dir

kN

X-Dir

kN

X-Dir

kN

X-Dir

kN

X-Dir

kN

Base Shear 14182.55 13856.14 13953.91 13795.11 13643.26 13700.52

Weight 419819.5 419819.5 419819.5 418457.4 418457.4 418457.4

Graphical representation of Base Shear

Continue…

Comparison between structure with RCC Outrigger and Belt truss at different positions. Comparison of Top Storey Displacement

• Above results shows the comparison of storey displacement, storey drift ratio and base shear for Bare Frame, Frame with shear wall (different location of shear wall) and outrigger systems (different locations and patterns).

• Outrigger structural system is effective when outrigger beam is placed at its optimum location.

• In 30 storey building optimum position of outrigger was found at 20th storey.

• Structure using shear wall at center and corner gives the less displacement than the structure with single outrigger at its optimum position, but its base shear is very higher than structure with outrigger system.

• Therefore outrigger structural system is more economical and effective than the shear wall.

CONCLUSION CONCLUSION

• From the comparison for storey drift, it can be concluded that location of outrigger

beam gives the least storey drift at that storey.

• Comparison has been made between RCC & Steel Outrigger systems for 10 th, 20th, 30th

storey locations in 30 storey building, conclusion can be made that RCC Outrigger

gives less displacement than steel outrigger.

• Therefore RCC outrigger is more effective than Steel outrigger

• Material for outrigger like RCC and Steel does not give major difference in base shear.

FUTURE SCOPEFUTURE SCOPE

• Same structural configuration can be used for steel structure and composite section as a

outrigger beam.

• Buildings with irregularities can be further proposed to this lateral load resisting systems.

• This subject further can be elongated for the study in wind along with dynamic wind

effect.

ACKNOWLEDGEMENTS

• I am thankful to Shri. S. K. Patel sir , Additional Secretary & Chief Engineer, R & B Department, And Director-STC , Government of Gujarat, Gandhinagar, for his Excellency, valuable support, Guidance and continuous inspiration for the paper.

• The work carried out in the Department of Civil Engineering,C.S.P.I.T, Charusat University, Changa,during the course of M.tech. By Jugal Senghani guided by Ms. Pooja Mistry and me. We really thankful to the Department of Civil Engineering,C.S.P.I.T, Changa.

REFERENCES REFERENCES 1. Agarwal, P. & Shrikhande, M., 2006. Earthquake Resistant Design of Structures. Delhi: PHI learning Private Limited.

2. Bungale, T. S., 2010. Reinforced Concrete Design of Tall Building. s.l.:CRC Press is an imprint of Taylor & Francis Group.

3. Choi, H., Ho, G., Joseph, L. & Mathias, N., 2012. Outrigger Design for High-Rise Buildings. Chicago: Council on Tall Buildings and Urban

Habitat.

4. Chopra, A. K., 2007. Dynamics of Structures. 3rd ed. s.l.:person education, Inc.

5. Gursale, M. & Patil, P. S., 2015. Comparative Parametric Study of Linear and Nonlinear Behavior of Multisory Structures. International

Journal of Research in Engineering and Technology, 4(4).

6. Herath, N., Haritos, N., Ngo, T. & Mendis, P., 2009. Behaviour of Outrigger Beams in High rise Buildings under Earthquake Loads.

Australian Earthquake Engineering Society.

7. Kamath, K., N, D. & Rao, A. U., 2012. A Study on Static and Dynamic Behavior of Outriggr Structural System for Tall Building. Bonfring

International Journal of Industrial Engineeringand management Science.

8. Patel, D., Amin, J. A. & Shah, N. D., n.d. A Parametric Study on Effectiveness of Shear Wall Patterns in Reducing Lateral Displacement &

Inter Storey Drift.

9. Shah, H. J., 2014. Reinforced Concrete. 7th ed. s.l.:Charotar.

10. Shivacharan, K., Chandrakala, S., Narayana, G. & N, K., 2015. Analysis of Outrigger system for tall vertical irregularites structures

subjected to lateral loads. International Journal of Research in Engineering and Technology.