IJSTE - International Journal of Science Technology & Engineering | Volume 3 | Issue 12 | June 2017 ISSN (online): 2349-784X
Analysis of Outrigger Structural System for Tall Building Subjected to Lateral Loads Preeti. M. Nagargoje PG Student Department of Civil Engineering Saraswati College of Engineering, Kharghar Navi Mumbai, India
Shilpa. Kewate Associate Professor Department of Civil Engineering Saraswati College of Engineering, Kharghar Navi Mumbai, India
Abstract The aim of this paper is to analyze the outrigger structural system for tall building subjected to lateral loads. Due to the urbanization and industrialization metro cities facing the problem of land so that tall buildings are generally preferred in metro cities. When the building increases the height, stiffness is very important criteria which can be reduced sufficiently by providing the outrigger beam between shear wall and outer columns. 40 storey RCC models has been developed and analyzed which is subjected to lateral loads by using ETABS software. The parameters of earthquake and wind load has been defined as per IS 1893 (Part-1): 2002 and IS 875 (Part-3): 1987 respectively. Dynamic analysis has been carried on RCC model without outrigger by using response spectrum method. The Results shows large values for lateral displacement, storey drift, velocity, acceleration, time period and base shear. To minimize the above parameters, four RCC models with single outrigger provided on 10th, 20th, 30th and 40th storey and one without outrigger model has developed and analyzed. The Comparative result show small reductions in above parameters. Therefore new four models has developed with Multioutrigger system (two outriggers) on different storey and analyzed. The comparative results of without outriggers model and Multioutriggers models shows considerable changes in parameters. This paper also have objective to find optimimum positions of Multioutrigger in Rcc model. From the result it is concluded that the provision of Outrigger system is very effective in Minimizing the lateral displacement, storey drift, base shear, acceleration, velocity. Keywords: Outriggers, ETABS, storey drift, lateral displacement ________________________________________________________________________________________________________ I.
INTRODUCTION
Due to increases in urbanization and less availability of land in Metro cities, the height of the building increases and become narrower therefore the stiffness of the building reduces. The stiffness of the structure becomes more important. For building taller than certain height, moment resisting frame structure, shear wall structure, braced frame structure, tubular structure may not provide adequate stiffness to resist lateral load therefore introduction of outrigger beams between the shear walls and exterior columns is more commonly used to give sufficient lateral stiffness to the structure. Outriggers are Stiff beam that connects the shear wall to the exterior columns to enhance building overturning stiffness and strength. When Tall building subjected to the lateral forces developed by the wind or earthquake, that forces are resisted by the system of Outriggers. Column resists the rotation of shear wall. This would result in significant reduction in lateral displacement at the top and base movement.
Fig. 1: Shows Elevation of Outrigger
II. MODELLING AND ANALYSIS Dynamic analysis of outrigger structural system for G+40 RC building. The model considered for this study is 120 m high rise reinforced concrete building frame. The Plan area of the Structure is 35m x 21 m with columns spaced at 3.5 m from center to
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Analysis of Outrigger Structural System for Tall Building Subjected to Lateral Loads (IJSTE/ Volume 3 / Issue 12 / 038)
center and central core shear wall. The height of each storey is 3m and all the floors are considered as Typical Floors. No of bays in X- directions are 10 and Y- direction are 6. An elevation and plan view of a typical structure is shown in fig. 2.
Fig. 2: Typical Floor Plan of 40 Storeys
The structure is analyzed as per the loading combinations provided in IS: 456-2000. The following load combinations are used to determine the maximum lateral deflection in the structure. i) DL+LL ii) DL+LL±WL(x or y) iii) DL+LL±EL(x or y) iv) DL±WL(x or y) v) DL±EL(x or y). Loading Parameters (IS 875 (Part – 2): 1987) Dead Load = 2 KN/m^2 Unit weight of Concrete = 25kN/m3 Unit weight of floor finish = 24kN/m3 Unit weight of Brick walls = 20kN/m3 Live Load (IS 875 (Part – 2): 1987) Commercial area = 4.0kN/m2 Staircases = 3.0kN/m2 Terrace = 2.0kN/m2 Wind Load ( IS 875 Part -3 ) : 1987) Basic wind speed (Vb) = 44m/sec Design Wind Speed (Vz) = Vb * k1 * k2 * k3 Design Wind Pressure (Pz) = 0.6 * Vz2 k1 = Probability factor = 1 k2 = Terrain, height and structure size factor. k3 = Topography factor. Parameters of Seismic loading as per IS 1893 (Part – 1): 2002 Seismic zone: - III (Mumbai) Seismic Zone Factor: - 0.16 Response reduction factor (R) = 5 Importance Factor = 1.5 Soil Type: - II Medium Response Spectra in X- direction as per IS 1893 (PART-I) - 2002 Response Spectra in Y- direction as per IS 1893 (PART-I) - 2002 III. METHDOLOGY Table - 3.1 Relative height of outrigger H2=H is kept constant and H1 is varied. Model Name H2/H1(Relative height of outrigger ) Location of single Outrigger M1 4 10 Storey M2 2 20 Storey M3 1.33 30 Storey M4 1 40 storey
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Analysis of Outrigger Structural System for Tall Building Subjected to Lateral Loads (IJSTE/ Volume 3 / Issue 12 / 038)
Table - 3.2 Relative height of Multioutriggers Model Name Location of Multioutriggers M5 10th and 20th Storey M6 10th and 30th Storey M7 10th and 40th Storey M8 20th and 30th storey M9 20th and 40th storey M10 30th and 40th storey
IV. RESULTS AND DISCUSSION The result of response spectrum analysis for 40 storey building for single outrigger and multioutriggers system is given below Result of comparative study of RCC model without outrigger and single outrigger provided at different storey Table – 1 Storey Displacement storey Displacement(mm) Without outrigger 414.2 th 10 382.5 20th 350 30th 390 40th 400 Table – 2 Storey Displacement storey Displacement(mm) Without outrigger 10th 20th
342.9 283.5 284
30th
312.5
40th
347.9
Graph 1: Storey Displacement in X direction for Earthquake load
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Analysis of Outrigger Structural System for Tall Building Subjected to Lateral Loads (IJSTE/ Volume 3 / Issue 12 / 038)
Graph 2: Storey Displacement in X direction for Response spectra Table - 3 storey Displacement storey Displacement(mm) Without outrigger 363.3 10th 300 20th 312.5 30th 325 40th 350 Table - 4 storey Drift storey Drift (mm) Without outrigger 0.002418 10th 0.0024 20th 0.002 30th 0.0020 40th 0.0018
Graph 3: Storey Displacement in X direction for wind load
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Analysis of Outrigger Structural System for Tall Building Subjected to Lateral Loads (IJSTE/ Volume 3 / Issue 12 / 038)
Graph 4: Storey Drift in X direction for earthquake load Table - 5 storey Drift storey Drift(mm) Without outrigger 0.001979 10th 0.0019 20th 0.00179 30th 0.00165 40th 0.0012
Graph 5: Storey Drift in X direction for Response spectra
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Analysis of Outrigger Structural System for Tall Building Subjected to Lateral Loads (IJSTE/ Volume 3 / Issue 12 / 038)
Graph 6: Time period Table - 6 Velocity storey Velocity(mm/sec) Without outrigger 240.46 10th 222.4 20th 220.92 30th 222.44 40th 229.58 Table - 7 Acceleration storey Acceleration(mm/sec) Without outrigger 291.75 10th 284.59 20th 285.56 30th 281.52 40th 250.78
Graph 7: Velocity in X direction for response spectra
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Analysis of Outrigger Structural System for Tall Building Subjected to Lateral Loads (IJSTE/ Volume 3 / Issue 12 / 038)
Graph 8: Acceleration in X direction for Response spectra
Result of comparative study of RCC model without outrigger and Multioutrigger provided at different storey Table - 8 Displacement Storey Displacement(mm) Without outrigger 414.2 30th and 40th 323.3 20th and 30th 325.4 10th and 20th 372.3 10th and 30th 325.4 10th and 40th 358.4 20th and 40th 348.5 Table - 9 Displacement Storey Displacement(mm) Without outrigger 342.9 30th and 40th 311.2 20th and 30th 268.8 10th and 20th 257.8 10th and 30th 266.8 10th and 40th 293.2 20th and 40th 288.8
Graph 9: Storey Displacement in X direction for Earthquake load
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Analysis of Outrigger Structural System for Tall Building Subjected to Lateral Loads (IJSTE/ Volume 3 / Issue 12 / 038)
Graph 10: Storey Displacement in X direction for Response spectra Table - 10 Storey Drift Storey Drift(mm) Without outrigger 0.002481 30th and 40th 0.002331 20th and 30th 0.00155 10th and 20th 0.001677 10th and 30th 0.001937 10th and 40th 0.001711 20th and 40th 0.00199 Table - 11 Storey Drift Storey Drift(mm) Without outrigger 0.001979 30th and 40th 0.00188 20th and 30th 0.001229 10th and 20th 0.001322 10th and 30th 0.001523 10th and 40th 0.001378 20th and 40th 0.001612
Graph 11: Storey Drift in X direction for Earthquake load
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Analysis of Outrigger Structural System for Tall Building Subjected to Lateral Loads (IJSTE/ Volume 3 / Issue 12 / 038)
Graph 12: Storey Drift in X direction for response spectra Table - 12 Velocity Storey Velocity (mm/s) Without outrigger 240.46 30th and 40th 219.27 20th and 30th 208 10th and 20th 215.8 10th and 30th 213.02 10th and 40th 222.94 20th and 40th 215.9 Table - 13 Acceleration Storey Acceleration (mm/s) Without outrigger 291.75 30th and 40th 247.56 20th and 30th 279.84 10th and 20th 291.24 10th and 30th 286.12 10th and 40th 258.77 20th and 40th 250.56
Graph 13: velocity in X direction for response spectra
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Analysis of Outrigger Structural System for Tall Building Subjected to Lateral Loads (IJSTE/ Volume 3 / Issue 12 / 038)
Graph 14: Acceleration in X direction for response spectra
V. CONCLUSIONS The following conclusions are made from the present study 1) There is maximum Lateral displacement reduction 31.18 % when outrigger is provided at 10th floor due to wind load. 2) From storey drift result it is concluded that there is 42.59 % reduction when outrigger is placed at 40 th storey i.e. at top of building. 3) Use of outrigger did not show any significant change in base shear, as the total force acting on structure does not change with addition of outrigger. 4) Hence it can be concluded that outriggers are efficient in controlling the storey displacement, storey drift. The use of outrigger system in high-rise buildings increases the stiffness and makes the structural form efficient under lateral load REFERENCES [1] [2] [3] [4] [5]
[6] [7] [8] [9] [10] [11]
[12] [13] [14] [15] [16] [17]
Kiran Kamath, N. Divya, Asha U Rao, “ A Study on Static and Dynamic Behaviour of Outrigger Structural System for Tall Buildings”, Bonfring International Journal of Industrial Engineering and Management Science, Vol. 2, No. 4, December 2016. Kiran Kamath1, Avinash A. R.2, Sandesh Upadhyaya K.3, “ A Study on the performance of multi-outrigger structure subjected to seismic loads”, IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) e-ISSN: 2278-1684, p-ISSN: 2320-334X PP 27-32 . N. Herath, N. Haritos, T. Ngo & P. Mendis, “Behaviour of Outrigger Beams in High rise Buildings under Earthquake Loads”, Australian Earthquake Engineering Society 2009 Conference. Srinivas Suresh Kogilgeri1, Beryl Shanthapriya2. “A study on behaviours of outrigger system on high-rise building steel structure by varying outrigger depth”, IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308. P.M.B. Raj Kiran Nanduri , B.Suresh2, MD. Ihtesham Hussain , “ A Optimum Position of Outrigger System for High-Rise Reinforced Concrete Buildings Under Wind And Earthquake Loadings ”, American Journal of Engineering Research (AJER) e-ISSN : 2320-0847 p-ISSN : 2320-0936 Volume-02, Issue08, pp-76-89 . MSc. Rafael Shehu, “ Ductility of Outrigger Typologies for Highrise Structures”, IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) e-ISSN: 2278-1684,p-ISSN: 2320-334X, Volume 12, Issue 2 Ver. VI (Mar - Apr. 2015), PP 34-41 www.iosrjournals.org. Kashiwa Sagar K., Prof. M.R.Wakchaure , Anantwad Shirish , “Effects of numbers and positions of shear walls on seismic behaviour of multistorey structure”, Kashiwa Sagar K.et al. / IJAIR ISSN: 2278-7844. M.R Suresh1 Pradeep K.M2, “Influence of Outrigger System in RC Structures for Different SeismicZones”, IJSRD - International Journal for Scientific Research & Development| Vol. 3, Issue 05, 2015 | ISSN (online): 2321-0613. Abbas Haghollahi, Mohsen Besharat Ferdous, Mehdi Kasiri,” Optimization of outrigger locations in steel tall buildings subjected to earthquake loads. Z. Bayati1, M. Mahdikhani2 and A. Rahaei3, “Optimized use of multi-outriggers system to stiffen tall buildings”, The 14thWorld Conference on Earthquake Engineering October 12-17, 2008, Beijing, China. P.M.B. Raj Kiran Nanduri1, B.Suresh2, MD. Ihtesham Hussain3, “Optimum Position of Outrigger System for High-Rise Reinforced Concrete Buildings Under Wind And Earthquake Loadings, American Journal of Engineering Research (AJER) e-ISSN : 2320-0847 p-ISSN : 2320-0936 Volume-02, Issue-08, pp-76-89 www.ajer.org. Mohd,Abdu,Sattari,Sanjeevrao ,Madan Mohan3, “Deflection Control in High Rise Building Using Belt Truss and Outrigger Systems” , International Journal of Applied Sciences, Engineering and Management ISSN 2320 – 3439, Vol. 03, No. 06, November 2014, pp. 44 – 53. John Merrick1, Radu Bliuc2 and Mike Haysler3 , “Design of a Composite Outrigger Structure for the Dubai Tower, Doha ”, Dr.K.S.Sathyanarayanan, A.Vijay, S.Balachanda (2012) , “Feasibility Studies on the Use of Outrigger System for RC Core Frames ”, VOLUME 1 NUMBER 3 (May/June 2012) ISSN: 2277–1891. Baldev D. Prajapati1 & D. R. Panchal2 (2013), “Study of seicmic and wind effect on multy story R.C.C., steel and composite building ” , International Journal of Advances in Engineering & Technology, Sept. 2013. ©IJAET ISSN Vol. 6, Issue 4, pp. Sarfaraz I. Bhati¹, Prof. P. A. Dode², Prof. P. R. Barbude³ (2016 ) , “Analysis of High Rise Building with Outrigger Structural System ” , International Journal of Current Trends in Engineering & Research (IJCTER) e-ISSN 2455–1392 Volume 2 Issue 5, May 2016 pp. 421 – 433. Kasliwal Sagar K. #1, Prof. M.R.Wakchaure *2, Anantwad Shirish #3 (2012) , “effects of numbers and positions of shear walls on seismic behaviour of multistorey structure ” .
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Analysis of Outrigger Structural System for Tall Building Subjected to Lateral Loads (IJSTE/ Volume 3 / Issue 12 / 038) [18] Prateek n. Biradar1, Mallikarjun S. Bhandiwad2 (2015 ) , “a performance based study on static and dynamic behaviour of outrigger structural system for tall buildings ” , (IRJET) e-ISSN: 2395 -0056 Volume: 02 Issue: 05 Aug-2015 www.irjet.net p-ISSN: 2395-0072 . [19] Krunal Z. Mistry1, Proff. Dhruti J. Dhyani2 (2015) , “ optimum outrigger location in outrigger structural system for high rise building” , International Journal of Advance Engineering and Research Development Volume 2,Issue 5, May -2015 . [20] A S Jagadheeswari and C Freeda Christy (2016) , “ optimum position of multioutrigger belt truss in tall buildings subjected to earthquake and wind load” , International Journal of Advance Engineering and Research Development ISSN 0974-5904, Volume 09, No. 03. [21] 1Akash Kala, 2Madhuri Mangulkar, 3Indrajeet Jain (2014) , “Optimum position of outrigger with belt truss in tall building under horizontal load” , International Journal of Recent Advances in Engineering & Technology (IJRAET).
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