REVIEW ON BEHAVIOUR AND EFFECTIVENESS OF OUTRIGGER …

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REVIEW ON – BEHAVIOUR AND EFFECTIVENESS OF OUTRIGGER SYSTEM

FOR HIGH RISE SLENDER STRUCTURES

Abhishek Thota*1, Manas Rathore*2, Ashlesha Dubey*3 *1Research Scholar, Institute, Kalinga University, Naya Raipur, India.

*2Assistant Professor, Kalinga University, Naya Raipur, India.

*3Researcher, Kalinga University, Naya Raipur, India.

ABSTRACT

The several factors which made it mandatory for the nations and the world to come up with high-rise buildings.

The factors such as rapidly growth in the human population in urban areas as people migrate for livelihood and

safety. It’s challenging to construct a high-rise building as there are number of aspects which needs to be

considered are more in it as compared to low rise building such as lateral stiffness and stability. As the height of

buildings increases, its flexibility increases i.e., stiffness reduces this will subject the structures vibrations or

deflection due to due to earthquake and wind forces. There are many systems available to control the

deflections or vibrations, but outrigger system is considered to be the most advantageous and effective system

to improve lateral stiffness and overall structural stability of high-rise slender structures. The structural steel

and reinforced concrete are most commonly used for the construction of outrigger system elements. This paper

is to discuss the basic concepts of different outrigger systems and then study their effectiveness on the

behaviour of high-rise slender buildings through the literature review. The attempt of this study is that, the

designers of high-rise structures consider the deflections, strength, stability and stiffness as an important factor

that are affected by the lateral loads induced by wind and earthquake, then the stability assessment of high-rise

slender building is generally assessed by the comfort of humans residing in the structure under the wind effect.

The review also focuses on different approaches to locate the optimum position of outriggers in high rise

buildings.

Keywords: Lateral Stiffness And Stability, High-Rise Slender Structures, Outrigger System Elements.

I. INTRODUCTION

1.1 Overview

The outrigger concept originated with its use in boats known as Canoes. The outrigger was introduced to

strengthen and prevent the boat rollover, and the concept is understood in terms of feedback mechanism. The

feedback process is satisfactory, that is, when it improves the stability of the boat, gives negative feedback, as

it’s a different part than the boat. Fig. 1 shows boats attached with the outriggers.

This concept of outrigger present in the boat system can also be used for other systems that require stability in

overturning. So, the outrigger can be used for a high-rise slender structure where the central core with the

outrigger will reduce the displacement at the top and stabilize from overturning. Past many years it is recorded,

outriggers are used in a very slender system as in wind-resistant boats, it can be used extensively on high-rise

buildings with a narrow and slender structures that is subjected to the wind. Use of outriggers in high-rise

buildings began about 50 years ago say that the first exterior building was designed by Barbacki which was 47

floors, the Place Victoria Building in Montreal Canada, which was completed in 1962.

Fig. showing distribution of moments caused by moving persons in slender boats

having similar outrigger system





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1.2 Structural System

The structural members were assumed to carry primly the gravity load in the early structures. But now, due to

high strength materials in structural system, Slenderness is increased and building weight is reduced. Thus,

lateral loads such as wind and earthquake mainly taking into consideration. In tall buildings excessive drift due

to lateral load control by the lateral load resisting system, so non-structural and structural damage risk can be

minimized. Various types of lateral load resisting system for tall building.

1) Shear frames.

2) Interacting frames systems.

3) Partially tubular systems.

4) Tubular systems.

1.3 Types of Outriggers

On the basis of core connectivity there are two types of outrigger systems are mentioned below:

1. Conventional outrigger system.

2. Virtual outrigger system.

Conventional outrigger system Virtual outrigger system

1.4 Objectives and the Details of the Study:

• The aim of the present work is to study the use of outriggers and belt trusses placed at different locations

under wind or earthquake loads. The design of the wind load was calculated based on the earthquake load

obtained using IS 875 (Part 3) and IS 1893 (Part-1). The location of outriggers and belt trusses to reduce

lateral displacement, construction of drift and main moments can be achieved. The ETABS software

program is selected to perform analysis. The present study is limited to reinforced concrete (RC) multi-

storied symmetrical building.

• Hence study on effect of outrigger system for medium high-rise buildings is felt significant to arrive at the

optimum outrigger position and its efficiency.

1.5 Aim of the Study

• Analytical study on multi-storey reinforced concrete frame with single- and two-level outriggers for seismic

loading for multi-storey buildings using standard structural software.

• The parameters held constant in the analytical study are the flexural stiffness of the outrigger members, the

axial stiffness of the outer pillars, the number of levels of the outrigger and the position of the foundation. The

differing parameters in analytical studies are the locations of the outriggers.

II. LITERATURE REVIEW

J C de Honderkamp et al. Al. (2003) provided a graphical analysis method for the basic design of braced

frame high building structures with outrigger trusses subject to horizontal loading. It was reported. A total of

five rigidity should be included in the preliminary analysis of the proposed high-rise building structure, as the

horizontal deflection of the hanging frame and the reduction of bending moments are all affected by the rigidity

parameters.





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N. Herath et al. [2009] In their paper entitled "The Behavior of Outreach Beams in High Rise", they analyzed a

50-story model with Australian codes using Strand 7 software. The models used a pier wall on the perimeter of

the pair core using one or two outrigger beams. They are mostly focused on getting effective results from

different heights of outriggers. They concluded that it was 0.44 to 0.48 times higher than the building height.

S. Fawzia et.al. (2010) investigated control of deviations by effective use of belt truss and outrigger system at

60. A ground floor building with air cargo. An analysis of the fixed three-dimensional element was performed

one, two and three outrigger levels. Reduced diversification was 34%, 42% and 51% respectively Compared to

the model without any outrigger system, there is a dramatic decrease in floor drag by introduction in these

strict arrangements.

Abbas and Mohsin (2012) "Optimizing Outrigger Locations in Steel High Buildings Subject to Earthquakes".

The paper compares the optimal outrigger positions obtained through the response spectrum and non-linear

time history analysis. 3D model 20 and 25 storey steel frames connected by outriggers and belt truss systems

are considered. The paper concluded to be correct Response spectrum analysis leads to outrigger and belt

positions for floors 20 and 25 on floors 10 and 14, respectively. The correct positions for the time history

analysis of the model are on the 14th and 16th floors, respectively.

Kiran Kamath and Divya, Asha Yu Rao (2012) researched the RCC structure by changing its position with

and without outriggers, the height of the structure and the corresponding flexural rigidity. The outrigger was

placed on the upper floor, where a 30% reduction in maximum acceleration and a 50% reduction in drift were

observed.

Raj Kiran Nandureet Al. (2013) studied the exact location of outriggers and belt trusses in a thirty-story high-

rise building. A detailed comparison was made with the center and offset core to the different location of the

outriggers with and without belt trusses and studied their behavior for similar seismic induction. Desirable

increase in rigidity in buildings with outriggers Led to a reduction in system displacement.

III. METHODOLOGY • Dead load and live load calculation will be done for the selected layout.

• 3D analysis is performed because the structural system behaves like a vertical cantilever when subjected to

in-plane bending.

• Equivalent study load is assessed for Zone 5 as per IS 1893 (2002).

• Analysis and detection of displacement and other consequences by provision of outriggers at various levels.

• The efficiency of the outrigger is calculated based on the maximum lateral displacement.

• Lateral displacement of the core at any given time with the outrigger system = (difference between the lateral

displacement of the core and the core between the displacement of the outrigger / core alone) x 100

IV. MODELING AND ANALYSIS

Fig. ETABS example of a three-dimensional view of a multi-storey building with cap truss and

outrigger at 1/3 distance from the top





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V. CONCLUSION • Literature survey on outrigger structural proves its importance in tall building feedback control and shows

that it is efficient in tall buildings as a lateral load resistant technique by reducing the vibration response of the

building.

• The introduction of novelist concepts of damped outriggers has accounted for greater gains by reducing

building vibrations in addition to a reduction in lateral design forces.

• Although damp outrigger with controller is still an upcoming design and relatively new method in structural

control and monitoring, it has a lot of untapped potential in structural design and construction field.

• Based on the state-of-the-art review, it can be summarized that there is a need for more precise semi-active

and hybrid control techniques to make the outrigger structural system better and more economically viable.

VI. FUTURE SCOPE

• This paper discusses the development of the outrigger along with novel control system concepts from the

history of its use in canoe to the new concept of the dumped outrigger.

• Since the manufacturing sector is a complex data management system, big data technology can be

incorporated into processing, storage and databases to enhance structural response mitigation.

• The outrigger structural system can also be studied for stochastic optimal control that resembles randomness

in structural control.

• There is a new area of research in damp outrigger structural control involving adaptive control, robust control

and stochastic control.

VII. REFERENCES [1] Herath, N., Haritos, N., Ngo, T., & Mendis, P. (2009). Behaviour of outrigger beams in high rise buildings

under earthquake loads. In Australian Earthquake Engineering Society 2009 Conference (pp. 271-278).

[2] Nanduri, P. R. K., Suresh, B., & Hussain, M. I. (2013). Optimum position of outrigger system for high-rise

reinforced concrete buildings under wind and earthquake loadings. American Journal of Engineering

Research, 2(8), 76-89.

[3] Fawzia, S., & Fatima, T. (2010). Deflection control in composite building by using belt truss and

outriggers systems. Proceedings of the World Academy of Science, Engineering and Technology, 800-

805.

[4] Kamath, K., Divya, N., & Rao, A. U. (2012). A study on static and dynamic behavior of outrigger

structural system for tall buildings. Bonfring international journal of industrial Engineering and

Management Science, 2(4), 15-20.

[5] Jahanshahi, M. R., Malekinejad, M., & Rahgozar, R. (2012). A simple approach to static analysis of tall

buildings with a combined tube-in-tube and outrigger-belt truss system subjected to lateral

loading. International Journal of Engineering, 25(3), 289-300.

[6] Nanduri, P. R. K., Suresh, B., & Hussain, M. I. (2013). Optimum position of outrigger system for high-rise

reinforced concrete buildings under wind and earthquake loadings. American Journal of Engineering

Research, 2(8), 76-89.

[7] Asai, T., Chang, C. M., Phillips, B. M., & Spencer Jr, B. F. (2013). Real-time hybrid simulation of a smart

outrigger damping system for high-rise buildings. Engineering Structures, 57, 177-188.

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REVIEW ON BEHAVIOUR AND EFFECTIVENESS OF OUTRIGGER …