Comparative Study on Fixed Base and Base Isolated for Building on Sloping Ground
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This document compares the seismic performance of a 9-story reinforced concrete building located on sloping ground with and without base isolation. Six building models are analyzed with slopes of 0, 10, 20, and 30 degrees using ETABS software. Results show that base isolation increases drift but decreases base shear by around 55% as slope increases. Isolated buildings have displacement 2-3 times higher but time period increases 2.65 times. Base isolation at the foundation provides more efficient seismic performance compared to other positions. Lead rubber bearings are suitable for low to medium rise buildings on sloping sites.
![International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056
Volume: 04 Issue: 06 | June -2017 www.irjet.net p-ISSN: 2395-0072
© 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 1292
5.4 Storey Displacement
Fig21: Storey displacement in x-direction
Fig22: Storey displacement in y-direction
Base isolation devices increases storey drift due to
increase in storey displacement,alsoitcanbeconcluded
that as ground slope increases storey drift decreases
Decreases the base shear averagely by 55% as ground
slope increases from 20˚ to 30˚, Thus there is no
requirement of providingshearwall,bracingandductile
detailing for beam column joint Time period increases
2.65 times in isolated base structure compared to fixed
base structures on sloping Ground
By providing base isolation device at different level in
the building on sloping ground from results it can be
concluded that base isolation at foundation level gives
more efficient results as compared to other position
By providing led rubber base isolation thedisplacement
in base isolated buildings resting on 0°, 10°,20°, and 30°
ground slope were increases 2.14, 2.42 and 2.82 times
more respectively as compared to fixed base buildings.
When compare the design LRB isolator and base
reactions for 0°,10°,20°,30 sloped ground, it conclude
that the base isolation device (LRB) is suitableforlowto
medium rise buildings.
REFERENCES
[1]. Sumana C V , Raghu M E & Er. Rajesh Harugopp
(2012)“Comparative Study on Fixed base and Base
Isolated Buildings on Sloping Ground”.
[2]. Singh Y ,(2013) “the seismic behaviorofbuildinglocated
on sloping ground by using 9 storey RC building”.
[3]. Malla Karthik Kumar1,Vanka Srinivasa Rao2&Kusuma
Sundar Kumar,(2014) “The buildings on a sloping
terrain undergo severe torsion under earthquake
excitations due to considerable variationintheheightof
ground floor columns”.
[4]. Md. Arman Chowdhury1, Wahid Hassan,(2013)
“Comparative study of the Dynamic Analysis of Multi-
storey Irregular building with or without BaseIsolator”.
[5]. Ms. Minal Ashok Somwanshi and Mrs. Rina N.
Pantawane(2015) “Seismic Analysis of FixedBasedand
Base Isolated Building Structures”.
[6]. Nitya M1, Arathi S(2015), “Study on the Earthquake
Response of a RC Building with Base Isolation”.
[7]. Khante.S.N , Lavkesh R.Wankhade(2010), “Study of
seismic response of symmetric and asymmetric base
isolated building with mass asymmetry in plan”.
BIOGRAPHIES
Mr.Chiranjeevi.
PG Student, Department of Civil
Engineering, SJB Institute of
Technology, Bengaluru.
Mr.Manjunatha .L.
Assistant Professor, Department of
Civil Engineering, SJB Institute of
Technology, Bengaluru.
5. CONCLUSION](https://image.slidesharecdn.com/irjet-v4i8229-170921100524/85/Comparative-Study-on-Fixed-Base-and-Base-Isolated-for-Building-on-Sloping-Ground-6-320.jpg)
Comparative Study on Fixed Base and Base Isolated for Building on Sloping Ground
- 1. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 04 Issue: 06 | June -2017 www.irjet.net p-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 1287 COMPARATIVE STUDY ON FIXED BASE AND BASE ISOLATED FOR BUILDING ON SLOPING GROUND CHIRANJEEVI1, MANJUNATHA L2 1 P.G. Student, Civil Engineering Department, Sri Jagadguru Balagangadharanatha Institute of Technology, Bengaluru - 560060, Karnataka, India 2 Assistant Professor, Civil Engineering Department, Sri Jagadguru Balagangadharanatha Institute of Technology, Bengaluru - 560060, Karnataka, India ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract – Building on sloping ground one of the factors which reduces the capacity of the Structure due to the fact that the column in the ground storey are of different heights which leads to combination of Short column and long column. In this G+ 9 storey RCC building and the ground slope varying from 0° to 30° have been considered for the analysis and comparison has been made, The modeling and analysis of the building has been done by using structure analysis tool ETAB and the leadrubberbearingis considered to study the effect of building on sloping ground with base isolation and without base isolation during the earthquake. The results have been compared with the results of the building with and without base isolation. The seismic analysis was done by linear static analysis and the response spectrum analyses have been carried out as per IS:1893 (part 1): 2002. The results were obtained in the form of top storey displacement, drift, base shear and time period. Key Words: Base isolation, sloping ground, Hilly area, led rubber. 1. INTRODUCTION Generally the structures are constructed on level ground. In some areas the ground itself is a slope. In that condition it is very difficult to excavation, leveling and it is very expensive .Due to the scarcity of level ground engineers started construction on sloppy ground itself. Some of the hilly areas are more prone to the earthquake and it is one of the most dangerous natural hazards. Earthquake occurs due to sudden movement of the tectonic plates as a results it release large amount of energy in a few seconds. The impact of this function is most harmful because it affects large vicinity, and which occurs sudden and unpredictable. It causes large scale loss of life and property and damages important services such as, sewerage systems, communication,power,transportand watersupplyetc.They not only destroy towns, cities and villages, but the result leads to weaken the financially viable and social structureof the country. To defeat from the problem we need to find out the seismic performance and lateral stability of the building structure. 2. OBJECTIVES To analyze and study the effectiveness of lead rubber bearing used as base isolation system To study the existing literatures on different structures by use of base isolated and non-base isolated structures. To carry out comparison between fixed base and base isolated building on the basis of their dynamic properties like, base shear, storey drift, time period, storey displacement, 2. METHODOLOGY The six models of a building (g+9) are considered based on on their slope with base isolation and without base Isolation with slope 0°,10°,20°,30°, After modeling of structures in ETABS software, their response is studied under response spectrum and compared with load combination as envelope max and min by considering storey drifts, storey shear ,storey displacement ,time period ,maximum bending moment ,base reaction. Model 1: fixed base building for G+9 storey with slope 0° Model 2: fixed base building for G+9 storey with slope10° Model 3: fixed base building for G+9 storey with slope20° Model 4: fixed base building for G+9 storey with slope 30° Model 5: lead rubber bearing building for G+ 9 storey with slope 0° Model 6: lead rubber bearing building for G+9 storey with Slope 10° Model 7: lead rubber bearing building for G+9 storeys with slope 20° Model 7: lead rubber bearing building for G+9 storeys with slope 20°
- 2. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 04 Issue: 06 | June -2017 www.irjet.net p-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 1288 3.1 Material model The parameters considered for G+9 storey buildings are as follows: Table1: Building properties Storey G+9 Beam size 230 x 650mm Floor height 3.2 Wall thickness 200 Column size 500x500m m Slab thickness 150mm Live load on the slab 2kN/m2 Floor finish 1 kN/m2 Grade of Concrete M30 Grade of Steel Fe500 Yield Strength of Steel, 500000 kN/m2 3.2 Properties of Rubber Isolators Table2:Properties of lead rubber bearing U1 U2 U3 Linear effective stiffness Kn/m 15000 0 800 800 Nonlinear stiffness (kN/m) 2500 2500 Yield Strength (kN) 80 80 Post yield stiffness 0.1 0.1 3.3 Building Model And Elevations Fig-1: plan view of building Fig-2: Z-3d view of building
- 3. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 04 Issue: 06 | June -2017 www.irjet.net p-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 1289 Fig-3: 0° Slope for fixed base Fig5: 10° slope for fixed base Fig7:30° Slope for fixed base Fig-4: 20° Slope for fixed base Fig6: 0° slope for lead rubber Fig8:10° Slope for lead rubber
- 4. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 04 Issue: 06 | June -2017 www.irjet.net p-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 1290 Fig9:30° Slope for lead rubber Fig10:20° Slope for lead rubber 4. ANALYSIS REULTS FOR FIXED BASE 4.1 Storey drifts Fig11:Storey drifts in x-direction Fig12: Storey drifts in y-direction 4.2 Storey Displacement Fig13:Storey displacement in x-direction Fig14 :Storey displacement In y-direction
- 5. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 04 Issue: 06 | June -2017 www.irjet.net p-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 1291 4.3 Base Shear For Fixed Building Fig15:Base shear for fixed base 4.4 Time Period Fig16:Time period for fixed base 5. ANALYSIS REULTS FOR LEAD RUBBER BASE 5.1 Storey drifts Fig17: Storey drifts in x-direction Fig18: Storey drifts in x-direction 5.2 Base Shear Fig19:Base shear for lead rubber base 5.3 Time period Fig20: Time period for lead rubber base
- 6. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 04 Issue: 06 | June -2017 www.irjet.net p-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 1292 5.4 Storey Displacement Fig21: Storey displacement in x-direction Fig22: Storey displacement in y-direction Base isolation devices increases storey drift due to increase in storey displacement,alsoitcanbeconcluded that as ground slope increases storey drift decreases Decreases the base shear averagely by 55% as ground slope increases from 20˚ to 30˚, Thus there is no requirement of providingshearwall,bracingandductile detailing for beam column joint Time period increases 2.65 times in isolated base structure compared to fixed base structures on sloping Ground By providing base isolation device at different level in the building on sloping ground from results it can be concluded that base isolation at foundation level gives more efficient results as compared to other position By providing led rubber base isolation thedisplacement in base isolated buildings resting on 0°, 10°,20°, and 30° ground slope were increases 2.14, 2.42 and 2.82 times more respectively as compared to fixed base buildings. When compare the design LRB isolator and base reactions for 0°,10°,20°,30 sloped ground, it conclude that the base isolation device (LRB) is suitableforlowto medium rise buildings. REFERENCES [1]. Sumana C V , Raghu M E & Er. Rajesh Harugopp (2012)“Comparative Study on Fixed base and Base Isolated Buildings on Sloping Ground”. [2]. Singh Y ,(2013) “the seismic behaviorofbuildinglocated on sloping ground by using 9 storey RC building”. [3]. Malla Karthik Kumar1,Vanka Srinivasa Rao2&Kusuma Sundar Kumar,(2014) “The buildings on a sloping terrain undergo severe torsion under earthquake excitations due to considerable variationintheheightof ground floor columns”. [4]. Md. Arman Chowdhury1, Wahid Hassan,(2013) “Comparative study of the Dynamic Analysis of Multi- storey Irregular building with or without BaseIsolator”. [5]. Ms. Minal Ashok Somwanshi and Mrs. Rina N. Pantawane(2015) “Seismic Analysis of FixedBasedand Base Isolated Building Structures”. [6]. Nitya M1, Arathi S(2015), “Study on the Earthquake Response of a RC Building with Base Isolation”. [7]. Khante.S.N , Lavkesh R.Wankhade(2010), “Study of seismic response of symmetric and asymmetric base isolated building with mass asymmetry in plan”. BIOGRAPHIES Mr.Chiranjeevi. PG Student, Department of Civil Engineering, SJB Institute of Technology, Bengaluru. Mr.Manjunatha .L. Assistant Professor, Department of Civil Engineering, SJB Institute of Technology, Bengaluru. 5. CONCLUSION