comparative study of seismic analysis of transfer beams on … · 2018-06-26 · comparative study...

DOI:10.23883/IJRTER.2018.4323.7TFUI 98

Comparative study of seismic analysis of transfer beams on different

soil condition for zone II and zone III

Jadesh R1, Ashwini G2

1P G Student Department of Civil engineering, EWIT, Karnataka, India 2Associate Professor, Department of Civil engineering, EWIT, Karnataka, India

Keywords—Transfer beam, Floating column, Earthquake analysis, ETABS 16.2.0 v16

I. INTRODUCTION In the present-day construction of buildings in urban areas the main problem arises in the

accommodation of parking areas, reception lobbies etc. Behaviour of a building during earthquakes

depends on its overall size, shape and geometry, in accordance to how the earthquake forces are carried

to the ground. A characteristic column structural member by means of their dead weight, moment,

axial load, shear force etc., should carry the loads to ground with structure in safe condition. But

present-day columns are not in such a manner to carry to the ground, because of numerous architectural

views. In such cases columns handover above loads as a point load on beam. Such kind of column is

named as “Floating column”. This point load creates more bending moment on beam so that more area

of steel is required in such cases.

The complete structure of a model plays to keep structure safe while earthquake arises. A practical

study on building shows that, seismic forces are established at different level of floors that are taken

down along height to the ground by shortest path. Any discontinuity in the transfer way results in poor

performance of the structure. In study of seismic forces, the main retort parameters are Storey shear,

Storey displacement, Storey drift. These parameters are assessed in this project and critical section of

floating column building is observed.

FLOATING COLUMN- The Column whose bottom end does not extend to ground and loads are

handover above loading on beam as point load is called as Floating Column. Floating columns are

used for extra space for parking purpose, theatres, community hall etc., & does not pose any issue due

to only vertical loading condition but in earthquake loading condition, because of vertical

discontinuity. During earthquake, the seismic forces established in higher floors have to be transmitted

by the proposed cantilever beam due to overturning forces. Floating column is also vertical component

as its lower level rests on a beam which tends to turn it as horizontal member. The beam in turn assigns

the load to column below it.

TRANSFER BEAM- In a frame structure, as a load carrying system, when column is restricted for

downward due to some aesthetic considerations, when it rests on a beam, the kind of beam is named

as Transfer beam. A transfer beam carries a heavy load especially a column. Column is used to transfer

the load from above to beam. This type of transfer beam helps to avoid a column where requirement

of space more in high rise building.

International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 04, Issue 06; Month - 2018 [ISSN: 2455-1457]

@IJRTER-2018, All Rights Reserved 99

Floating Column

II. RELATED WORK

1. Ms. Waykule S. B (2011) – This paper conducts static linear analysis of different buildings

having floating columns at different floors & have also compared base shear and storey displacement.

Analysis on sap2000 v17, seismic zone factor as zone 5 along with suitable parameter frame structure

was done and result concluded that displacement of every storey of floating column building is more

compared to without floating column buildings.

2. Dr. C.P. Pise & C.M. Deshmukh (2012) – Studied behaviour of buildings with floating column

and without floating column for seismic analysis. The experiment was done through ETABS, here

seismic analysis used were both Linear Static Method and Time History Method considering zone 5

and hard soil property. They compared all models in Mode shapes, Time period, Frequency, Base

shear, Storey displacement. Result of this paper observed that building with floating column obtained

more time-period compared to without floating column and also storey drift & storey displacement

too.

3. Mahesha M (2015) - Studied the significance of expressly observing the vicinity of the floating

columns and significance of explicitly recognizing the presence of with and without floating column

in the investigation of building, furthermore alongside floating column, few complexities were

considered for G+16 story building at different alternative locations. The analysis model for Storey

drift, Displacement, Base shear concluded that lateral displacement of floating column in X & Y

direction were more compared to normal building.

4. Sabari S (2015) - Proposed to reduce the irregularities introduced by the floating column. They

create the 2D multi storey frame with and without floating column to study the responses of structure

under different earthquake excitations having different frequency content keeping the time duration

factor constant. result concluded that displacement of every storey of floating column building is more

compared to without floating column buildings.

5. Badgire Udhav S (2015) – This paper has analysed RCC frame (G+10) with floating columns

in different locations and investigated the base shear & drift between floating columns located in outer

periphery (4 sides & 2 Sides). It was concluded that probability of failure of floating column is more

in case of floating columns located at periphery on longer side than the floating column at periphery

on shorter side.

6. K.V. Sundheer & Dr. E. Arunakanthi (2015) – Investigated design & analysis of a high-rise

building with and without floating column in an ETABS 2015 version. The building was of 15 floors

under seismic zone 3 on medium soil type. The method was done through both linear and non-linear

method. The analysis model for Storey drift, Displacement, Base shear concluded that lateral



displacement of floating column in X & Y direction were more compared to normal building. Also

concluded that use of floating columns should not be done unless proper purpose and requirements

were in place.

7. Avinash Pardhi (2016) - Studied seismic analysis of RCC building with & without floating

columns. The response of floating column to the seismic forces and also study of weak critical

members of the structure having floating column were taken up in the study. Concluded that soft soil

with result in Ah are more followed by medium and hard. Displacement is more in case of soft soil

while less in hard soil.

8. T. Chandra Shekhar (2016) - Compared seismic analysis of a floating column building and a

normal building using ETABS-2013. In this a residential building with 6 storey and 12 storeys were

analysed with columns, beams and slabs. The buildings were analysed and designed with and without

edge columns at base storey. The buildings were analysed in two earthquake zones with medium soil.

Results have been checked out for First Mode Time period, Horizontal seismic Co-efficient, Top storey

displacement. Concluded that soft soil with result in Ah are more followed by medium and hard.

Displacement is more in case of soft soil while less in hard soil.

9. G. Hemanth & B. Bhanupriya (2017) – Earthquake analysis of multi-storied buildings with

floating column using ETABS were taken up. With the model using seismic zone as 2 and referring

code of IS 1893-2000 soil type as hard the paper concluded that mode shapes as a result of using brick

infill tend to increase the storey stiffness of building. concluded that displacement of every storey of

floating column building is more compared to without floating column buildings.

10. Dheeraj Sangtiani & Vardhaman Jain (2017) – Studied behavior of building under different

type of soil conditions. Seismic parameters were considered as per IS 1893: 2002 and using zone as

severe exposure condition, zone 5. Results have been checked out for First Mode Time period,

Horizontal seismic Co-efficient, Top storey displacement. Concluded that soft soil with result in Ah

are more followed by medium and hard. Displacement is more in case of soft soil while less in hard

soil.

III. OBJECTIVES

a. Performance of floating column structure on a multi storey building under earthquake

excitations.

b. Seismic retort of soft storey structure with various shapes of shear wall.

c. Modelling of multi-story structure with floating column under different types soil condition

using finite element software ETABS v16.2.0

d. Dynamic analysis through Response Spectrum method for all the models

e. Comparative study equipped for both Zone II and Zone III with different kind of soils.

IV. METHODOLOGY

Seismic analysis is response calculation of a building frame structure to earthquake. It is a kind of

process earthquake engineering, structural design.

Linear Static Method: This method defines a series of forces acting on a building to represent the effect

of earthquake ground motion, typically defined by a seismic design response spectrum. It assumes that

the building responds in its fundamental mode. The response is read from a design response, given the

natural frequency of building.



Time History Method: A linear time history analysis overcomes all the disadvantages of modal

response spectrum analysis, provided non-linear behaviour is not involved. This method requires

greater computational efforts for calculating the response at discrete time.

V. STRUCTURAL MODELLING AND LOADING

A G+5 multi storey building with floating column located in zone II and zone III for different soil

condition of Indian as per code IS 1893(part1):2016 were taken for the investigation. In this study a

floating column of zone II in medium soil type as model 1 and hard soil as model 2. In model 3

considered as floating column of zone III in medium type and model 4 as floating column of zone III

in hard type of soil. loading condition and combination are applied to the structure as per IS standards.

Parameters Model 1 Model 2 Model 3 Model 4

Soil type Medium Hard Medium hard

Seismic zone II II III III

Response reduction factor 3 3 3 3

Importance factor 1 1 1 1

Height of building (m) 30.20 30.20 30.20 30.20

Thickness of slab 125/150/175/200/225/250 TB1000 TB1200 TB600 TB800

Beam sizes 200x600 200x750 300x600 300x750 400x750

Column sizes 200x750 200x800 200x1000 300x800 300x1000 500x800 500x1000

Material properties M25/M30/M35/M40/HYSD500

Figure 1. Plan view of bare frame model Figure 2. 3D view of bare frame model

Figure 3. 3D view of floating columns appears in 1st floor



Figure 4. 3D view of tube in tube model

VI. RESULTS AND DISCUSSIONS

The behaviour of each model is studied and the results are tabulated. The variation of systematic

parameters like story lateral displacement, story drift, storey shear and horizontal seismic co-efficient

has been studied for both equivalent static analysis method and response spectrum analysis method.

The results of all the models are observed and the most suitable model is selected by comparing the

results of each and every model.

6.1 Storey Displacement: Storey displacement is lateral movement of the structure caused by lateral

force. The deflected shape of structure is most important and most clearly visible point of comparison

for any structure. No other parameter of comparison can give a better idea of behaviour of the structure

than comparison of storey displacement.

Figure 5. Variation of displacement for zone-2 and zone-3

0

1

2

3

4

5

6

7

0 10 20 30 40 50 60 70

NU

MB

ER

OF

FL

OO

RS

DISPLACEMENT IN mm

LATERAL DISPLACEMENT IN X-DIRECTION

ZONE II-HARDZONE II - MEDIUMZONE III- HARDZONE III- MEDIUM



6.2 Storey Drift:

Figure 6. Variation of drift for zone-2 and zone-3 for hard and medium type of soil

We can see that variation in drift as storey height increases. We can clearly see that there is a reduction

of lateral drift for hard type of soil structure and medium type of soil structures. From the above plotted

graph, we can absorb that storey drifts are increased by 12% in zone 3 of hard structure compare to

zone 2 of hard structure and 15% zone 3 of medium structure compare to zone 2 of medium structure

for equivalent static in X and Y directions.

6.3 Base Shear:

Figure 7. Variation of base shear for static and response spectrum analysis

Base shear of the building frames vary when the irregularity has been introduced in the structure. As

the irregularity increases, the base shear goes on increases. The comparison of Base shear using

Equivalent static and Response spectrum methods are plotted above we can see that there is a slight

increase in Base shear when structures goes alter in structure. From the above plotted graph, we can

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

0.0035

0.004

0 1 2 3 4 5 6 7

DR

IFT

IN

mm

NUMBER OF FLOORS

STOREY DRIFT IN X-DIRECTION

ZONE II-HARDZONE II - MEDIUMZONE III- HARDZONE III- MEDIUM

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

Hard Medium

Base Shear

Zone 2 EQX Zone 2 EQY Zone 3 EQX Zone 3 EQY



absorb that Base shear is increased by 28% in zone 3 of hard structure compare to zone 2 of hard

structure and 32% zone 3 of medium structure compare to zone 2 of medium structure for equivalent

static in X and Y directions.

6.4 Horizontal seismic co-efficient: As Per IS 1893-2016 part 1, Ah is depending on the soil

conditions. Where (Sa/g) is the parameter which varies per the soil condition.

Figure 12. Variation of horizontal seismic co-efficient for zone-2 and zone-3

VII. CONCLUSIONS

The study presented in the paper compares the difference between types of soil condition as well as

zones, Zone II and Zone III with floating column on a transfer beam. The following conclusions were

drawn based on the investigation.

1. By the application of lateral loads in X direction on all 4 models, the lateral displacement of

floating column building in X direction of medium soil are more compared to that of a hard type

of structure. Also, Zone III building structure are more critical than Zone II.

2. The building with floating column experienced baser shear in Zone III than that of Zone II. This

is due to the use of more quantity of materials and seismic condition of zone. So, quantity of steel

is more as compared to Zone II.

3. By investigating of Horizontal Seismic co-efficient, the medium soil shows more value followed

by the hard soil.

4. The final conclusion as we compared for Zone II and Zone III, the critical Zone III should be

avoided for use of floating column because of uneconomical structure compared to Zone II. Also,

do not prefer to construct floating column in buildings unless there is a proper purpose and

functional requirement for those. If they are to be provided, then proper care should be taken while

designing structure.

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09

Zone II

Zone III

Horizontal seismic co-efficient (Ah)

Medium Hard



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comparative study of seismic analysis of transfer beams on … · 2018-06-26 · comparative study...

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