effects of drift in soft storied rcc - … · limits under zones- iii by etabs respect to bare and...

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International Journal of Civil Engineering and Technology (IJCIET)Volume 8, Issue 8, August 2017, pp.

Available online at http://http://www.iaeme.com/ijciet/issues.

ISSN Print: 0976-6308 and ISSN Online: 0976

© IAEME Publication

EFFECTS OF DRIFT IN

Ph.D. Scholar,

Professor

Maulana Azad National Institute of Technology, Bhopal (MP)

ABSTRACT

This paper emphasizing the importance of seismic safety measures which will be

suitable and useful for the professionals, builders so that ill constructions practices

can be corrected resulting safe, economic and correct design as per the needs

according to the seismic zones and site conditions. Mostly it is seen that soft storey

exhibits higher stresses at the columns of first floor levels and the columns fails as the

formation of plastic hinges are not formed on the predetermined locations causing

crushing of columns. Soft storey also reduces the lateral stiffness of the load resisting

system causing progressive collapse of building in severe earthquakes .This paper

highlights the important parameters affecting the behavior of building during

earthquakes. Here building is being analyzed to know the effects of drifts and drifting

limits under zones- III by ETABS

respect to bare and infilled frames for drifts, displacements’, shear force and bending

moments etc.

Key words: Bare fame, infilled frame, drift, seismic zones, storey shear, Seismic

forces, interstorey drift.

Cite this Article: M.P. Mishra and Dr. S.K. Dubey

RCC Buildings. International Journal of Civil Engineering an

pp. 113–120.

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1. INTRODUCTION

The mass of the building is important parameter i

earthquake induces inertia force

design a building which will behave elastically during earthquakes without damage. Thus

traditional earthquake resistant design philosophy states that normal building should be able

to resist. (a) Minor shaking with no damage to structural and non

Moderate shaking with minor damage to structural elements, and some damage to non

structural elements; and (c) Severe shaking

IJCIET/index.asp 113 [email protected]

International Journal of Civil Engineering and Technology (IJCIET) 2017, pp. 113–120, Article ID: IJCIET_08_08_013

http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=8&IType=8

8 and ISSN Online: 0976-6316

Scopus Indexed

EFFECTS OF DRIFT IN SOFT STORIED RCC

BUILDINGS

M.P. Mishra

Maulana Azad National Institute of Technology,

Bhopal (MP), India

Dr. S.K. Dubey

Professor, Dept. of Structural Engineering,

Maulana Azad National Institute of Technology, Bhopal (MP)



n be corrected resulting safe, economic and correct design as per the needs



rmation of plastic hinges are not formed on the predetermined locations causing



lights the important parameters affecting the behavior of building during


III by ETABS-2016 and results obtained has summarized with

and infilled frames for drifts, displacements’, shear force and bending

Bare fame, infilled frame, drift, seismic zones, storey shear, Seismic

M.P. Mishra and Dr. S.K. Dubey, Effects of Drift in Soft Storied

. International Journal of Civil Engineering and Technology, 8(8), 2017,


of the building is important parameter in addition to the building stiffness, because

inertia force that is proportional to the building mass. It is not possible to


esistant design philosophy states that normal building should be able

with no damage to structural and non-structural elements, (b)

with minor damage to structural elements, and some damage to non

Severe shaking with damage to structural elements, but with NO

[email protected]

asp?JType=IJCIET&VType=8&IType=8

SOFT STORIED RCC

Maulana Azad National Institute of Technology,

Maulana Azad National Institute of Technology, Bhopal (MP), India



n be corrected resulting safe, economic and correct design as per the needs



rmation of plastic hinges are not formed on the predetermined locations causing



lights the important parameters affecting the behavior of building during


2016 and results obtained has summarized with

and infilled frames for drifts, displacements’, shear force and bending

Bare fame, infilled frame, drift, seismic zones, storey shear, Seismic

f Drift in Soft Storied

Technology, 8(8), 2017,


n addition to the building stiffness, because

that is proportional to the building mass. It is not possible to


esistant design philosophy states that normal building should be able

structural elements, (b)

with minor damage to structural elements, and some damage to non-

with damage to structural elements, but with NO

M.P. Mishra and Dr. S.K. Dubey

http://www.iaeme.com/IJCIET/index.asp 114 [email protected]

collapse (to save life and property inside/adjoining the building).Generally multi-storeyed

RCC framed buildings with masonry infills are popular form of construction in urban and

semi urban areas around the world. These building are generally designed treating as framed

structures without regard to structure action to masonry infill walls, thus in designing these

walls are considered to be non-structural elements. Normally the RC frame is filled with brick

masonry as social and functional needs but for parking of vehicle, shops and reception etc. we

have to provide open first storey. As we know from the past earthquakes which has illustrated

the potential hazard associated with building having open first storey particularly in higher

seismically active zones. But due to necessity multi-storey building with parking floor are

vulnerable to earthquake. The main objective of this study is to find the real behaviour of a

building treating as bare frame, infilled frame and with a comparison to the soft storey

structure. The presence of a soft-storey in a building also results in a centralized excessive

drift in a building that causes heavy damage or collapse of the storey during a severe

earthquake. The presence of wall in upper storey makes them much stiffer as compare to open

ground storey, thus the upper storey moves almost together as a single block and most of

horizontal displacement of building occurs in ground storey itself, so causing collapse of a

building. It is concluded that drift and strength demands in soft-storey building is very large

thus it is very important to incorporate the stiff column at soft-storey. The classification of

soft-storey/ weak storey as per I.S.-1893-2002 states that in the soft-storey, which has lateral

stiffness less than 70% of that in storey above or less than 80% of average lateral stiffness of

the three storey above, whereas the weak storey is one in which the storey lateral strength is

less than 80% of that in storey above. For a rigid frame structure drift is dependent on total

height of building, number of bays, length and breadth of the girders and beams including its

shear value etc.

As per Indian I.S.-1893-2002 code storey drift limitations states that it should not more

than 0.004 times the storey height as per the clause 7.11.1, 7.11.2 and 7.11.3. Whereas per

ASCE-7.02 also states that structure up to four storey, storey drift can vary 0.015H to 0.025H

{H-Total height of building}. For a moment resistant frame building should have maximum

storey drift of the order of 0.75% of storey height. NBCC-1995 requires that maximum inter-

storey drift be limited to 1% of storey height for post disaster building and 2% for all other

buildings. As per Peru (NCC-1977) code states that for RCC building storey drift can be 0.7%

of storey height. As recommended by many researchers a total collapse mechanism design is

desirable to control drift demand so primary factor governing first storey drift demand is the

first storey strength itself.

2. DESCRIPTION OF STRUCTURAL MODEL

The study is carried out on reinforced concrete moment resisting framed G+6 storey buildings

with soft storey at different levels. The plan of building is same for all models. Height of each

storey is 3.2 m. The building has plan dimensions 45m x 30m. In the analysis special RC

moment-resisting frames (SMRF) is considered. Other relevant data is given as below.

Effects of Drift in Soft Storied RCC Buildings


Sr. No. Parameters

1 No. of storey

2 Floor height

3 Span length X- direction

4 Span length Y- direction

5 Height of model taken

6 Single bay length in X

7 Single bay length in Y

8 No. of bay in X- direction

9 No. of bay in Y- direction

10 Area of plan

11 Column

12 Beam

13 Slab

14 Wall

Figure 1 Model Plan

Figure 3 Model elevation in Y



Table 1 Structural detail of model

Parameters Value

G+6 (Total 7 floor)

3.5m, Base 1.5m

direction 45m

direction 30m

Height of model taken 26m (including base)

Single bay length in X- direction 5m

Single bay length in Y- direction 6m

direction 9 bay

direction 5 bay

45x30m2

300x300 mm

300x250 mm

150mm thickness

200mm thickness

Model Plan Figure 2 Model elevation in X

Model elevation in Y-Direction Figure 4 Model 3D diagram.

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Model elevation in X-Direction.

Model 3D diagram.


Sr. No. Design parameters

1 Unit weight of concrete

2 Unit weight of Infill walls

3 Characteristic Strength of concrete

4 Compressive strength of strong masonry (E

5 Compressive strength of weak masonry (E

6 Modulus of elasticity of steel

Table 3

Sr. No. Design Parameter

1 Seismic Zone

2 Zone factor

3 Response reduction factor

4 Importance factor

5 Soil type

6 Damping ratio

7 Frame type

Table 4

Models

Model-1 Bare frame model

Model-2 Masonry infilled

Model-3 Ground floor open/ Soft

Model-4 Base + First floor open

Model-5 Base + Second floor open

Model-6 Base + Third floor open

Model-7 Base + Fourth floor open

Figure 5 Model 1


IJCIET/index.asp 116 editor@iaeme

Table 2 Material properties

Design parameters Value

Unit weight of concrete 25 kN/m3

Unit weight of Infill walls 20 kN/m3

Characteristic Strength of concrete 415 MPa

essive strength of strong masonry (E m) 5000 MPa

Compressive strength of weak masonry (E m) 350 MPa

Modulus of elasticity of steel 2 ×105 MPa

Table 3 Detail of seismic data considered.

Design Parameter Values

III

0.16

Response reduction factor 5

Importance factor 1

Medium Soil-II

5%

Special Moment Resisting Frame

Table 4 Detail of different type of models.

Type of Model

Bare frame model

Masonry infilled

Ground floor open/ Soft-storey

Base + First floor open

Base + Second floor open

Base + Third floor open

Base + Fourth floor open

Figure 6 Model 2 Figure

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Value

Special Moment Resisting Frame

ure 7 Model 3



Figure 8 Model 4

.

3. ANALYSIS AND RESU

On the basis of model constructed for a building marked Model 1 to Model 7 and its analysis

is done considering the bare frame, infilled frame and soft

analysis storey displacement for various models and storey drift which is occurring is

tabulated below and the results obtained in different models has been compared to know the

real drifting effect particularly due to soft

remarkable effects of change in shear force and moments which is increasing abruptly

particularly at soft-storey level due to sudden change in stiffness with respect to other floor

for this certain precautionary m

mainly in severe earthquake.

Table 5 Storey Displacement for various building models for X

Storey Elevation M-1

Base 0 0

Ground 1.5 1.3

Storey 1 5 10.9

Storey 2 8.5 21.9

Storey 3 12 32.5

Storey 4 15.5 42.1

Storey 5 19 50.4

Storey 6 22.5 56.7

Roof 26 60.4



Figure 9 Model 5 Figure

Figure 11 Model 7

3. ANALYSIS AND RESULT


is done considering the bare frame, infilled frame and soft-storey at different level and after



rticularly due to soft-storey. In the analysis we have also seen the


storey level due to sudden change in stiffness with respect to other floor

for this certain precautionary measures to be adopted so that sudden collapsing can be reduced

Storey Displacement for various building models for X-Direction

M-2 M-3 M-4 M-5

0 0 0 0

3.01 3.5 1.6 1.8

3.2 22.2 1.65 1.8

3.4 22.4 19.3 2.1

3.6 22.2 19.8 21.0

3.8 22.3 19.9 21.1

4.2 22.3 19.9 21.2

4.3 22.5 20.0 21.3

4.4 22.6 20.0 21.5

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ure 10 Model 6


t different level and after



In the analysis we have also seen the


storey level due to sudden change in stiffness with respect to other floor

easures to be adopted so that sudden collapsing can be reduced

Direction (mm)

M-6 M-7

0 0

2.0 3.0

2.1 3.1

2.2 3.3

2.33 3.35

22.3 3.2

22.4 23.3

22.45 23.44

22.5 23.5


Table 6 Storey Displacement for various building models for Y

Storey Elevation M-1

Base 0 0

Ground 1.5 1.3

Storey 1 5 11.6

Storey 2 8.5 22.9

Storey 3 12 40

Storey 4 15.5 44.1

Storey 5 19 53.1

Storey 6 22.5 59.6

Roof 26 63.4

(A)

Figure

Table 7 Storey Drifts for various building models in X and Y direction

SNo. Storey Model 1 Model 2

0 Base 0

1 Ground 0.9 1.95

2 Storey1 6.3 0.19

3 Storey2 7.3 0.19

4 Storey3 7.0 0.2

5 Storey4 6.4 0.2

6 Storey5 5.5 0.1

7 Storey6 4.4 0.11

8 Roof 2.3 0.15

Table 8 Storey Drifts for various b

SNo. Storey Model 1 Model 2

0 Base 0

1 Ground 0.9

2 Storey1 6.7

3 Storey2 7.5

4 Storey3 7.2

5 Storey4 7.0

6 Storey5 5.7

7 Storey6 4.9

8 Roof 2.7

0

2

4

6

8

10

0 50 100

Sto

rey

No

.

Displacement (mm)

X-Direction


IJCIET/index.asp 118 editor@iaeme

Storey Displacement for various building models for Y-Direction

M-2 M-3 M-4 M-5

0 0 0 0

3.1 3.5 1.6 1.8

3.3 22.7 1.9 1.9

3.5 22.8 19.6 2.0

3.7 22.8 19.8 21.1

4.1 30.1 19.9 21.2

4.3 23 20.1 21.34

4.4 23.1 20.2 21.5

4.9 23.2 20.3 21.7

(B)

ure 12 Displacement graph in X and Y direction

Storey Drifts for various building models in X and Y direction

Model 2 Model 3 Model 4 Model 5

0 0 0 0

1.95 2.4 1.15 1.23

0.19 12.3 0.020 0.0195

0.19 0.0383 12.1 0.0192

0.2 0.0382 0.0445 12.9

0.2 0.03836 0.04422 0.04207

0.1 0.03845 0.04421 0.04189

0.11 0.03847 0.04419 0.04181

0.15 0.03839 0.04416 0.04172

Storey Drifts for various building models in Y direction

Model 2 Model 3 Model 4 Model 5

0 0 0 0

1.99 2.4 1.2 1.2

0.2 12.7 0.034 0.0377

0.21 0.1 12 0.0350

0.2 0.1 0.09 12.9

0.2 0.1 0.1 0.1

0.2 0.11 0.1 0.1

0.3 0.11 0.1 0.1

0.11 0.12 0.11 0.12

100

Displacement (mm)

M-1

M-2

M-3

M-4

M-5

M-6

M-7 0

2

4

6

8

10

0 50

Sto

rey

No

.

Displacment (mm)

Y-Direction

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Direction (mm)

5 M-6 M-7

0 0

2 2.7

2.1 2.7

2.2 2.9

21.1 2.2 3.0

21.2 22.3 3.1

21.34 22.5 23.1

21.5 22.5 23.2

21.7 22.6 23.5

(B)

Storey Drifts for various building models in X and Y direction

Model 6 Model 7

0 0

1.5 1.7

0.0228 0.0251

0.0227 0.0252

0.0229 0.0253

13.8 0.0254

0.03933 13.6

0.03975 0.037

0.03963 0.038

uilding models in Y direction

Model 6 Model 7

0 0

1.3 1.9

0.0432 0.035

0.0423 0.04

0.0427 0.04

13.9 0.05

0.09 13.2

0.1 0.1

0.13 0.12

100

Displacment (mm)

DirectionM-1

M-2

M-3

M-4

M-5

M-6

M-7



(A)

Figure 13 Graphical representat

4. RESULTS AND CONCL

From the analysis of the above building on the basis of different models for a soft

building at different level it is concluded that in bare frame there is no sudden displacement

take place this means displacement is progressive and increasing level till top level which

comes out to be 60.47mm at roof level

the total displacement is also progressive but it is very much less comparative

which is 4.4mm. It is nearly 13.2 times lesser than bare fr

severe earthquake also there is no drifting problem which can cause sudden collapse of

building because there is no sudden change in displacement a

prescribed by the different codes.

When a building is modelled treating a soft

then the displacement comes 22.6mm which is more than the infilled frame but less than bare

frame but when we see the displacement for first storey level in soft

22.6mm and in infilled frame (M

infilled frame. This sudden change can be controlled by different measure adopted

particularly at this level by putting stiffed column, core shear wall or bracing if needed to

control drift prescribed by different codes of India and abroad.

When we see the total displacement for the models M

different levels than the total displacement is below to M

put soft-storey at upper level the sudden displacement come done with respect to M

but it is beyond the limit of safety, so such type of building also need safety measures

mentioned above. Similar displacement results are also seen in Y

When we see the results tabulated for the drift in above table it is seen the sudden drift

increases particularly at the level of soft

floor level where as 0.19 for M

drift in infilled frame similarly in other models drift is changing many times with respect to

infill model at soft-storey levels.

Results which have obtained for the models M

to height also resembling as tabulated in the above tables. Thus it is concluded that drift is a

common phenomenon for high

the structure and causes serious loss of life and properties in case of major earthquake, so

above safety measures to be adopted without bothering the cost factor.

0

2

4

6

8

10

-10 0 10 20

Sto

rey

No

.

Drift (mm)

Storey Drift X-Direction



(B)

Graphical representation of Drift in X and Y Direction

4. RESULTS AND CONCLUSION

From the analysis of the above building on the basis of different models for a soft


e this means displacement is progressive and increasing level till top level which

comes out to be 60.47mm at roof level, but as we analysed a framed building as a infilled one

the total displacement is also progressive but it is very much less comparative

is nearly 13.2 times lesser than bare frame it means it indicate even in

earthquake also there is no drifting problem which can cause sudden collapse of

building because there is no sudden change in displacement and drift is within the limit

prescribed by the different codes.

When a building is modelled treating a soft-storey at ground floor or no infills at this level


but when we see the displacement for first storey level in soft

22.6mm and in infilled frame (M-3) it is 3.2mm only which is 7.06 times more than the


icularly at this level by putting stiffed column, core shear wall or bracing if needed to

control drift prescribed by different codes of India and abroad.

When we see the total displacement for the models M-4 to M-7 it means soft

than the total displacement is below to M-3 model which shows that when we

storey at upper level the sudden displacement come done with respect to M

but it is beyond the limit of safety, so such type of building also need safety measures

mentioned above. Similar displacement results are also seen in Y-direction.


increases particularly at the level of soft-storey. From the table drift is 12.3mm fo

floor level where as 0.19 for M-2 model. This shows that there is no sudden change in the


storey levels.

btained for the models M-1 to M-7 plotted graphically with respect


common phenomenon for high-rise and multi-storey building this may hamper the integrity of

he structure and causes serious loss of life and properties in case of major earthquake, so

above safety measures to be adopted without bothering the cost factor.

20

Direction

M-1

M-2

M-3

M-4

M-5

M-6

M-7

0

2

4

6

8

10

-10 0 10

Sto

rey

No

.

Drift (mm)

Storey Drift Y

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(B)

ion of Drift in X and Y Direction

From the analysis of the above building on the basis of different models for a soft-storey


e this means displacement is progressive and increasing level till top level which

but as we analysed a framed building as a infilled one

the total displacement is also progressive but it is very much less comparatively to bare frame

ame it means it indicate even in

earthquake also there is no drifting problem which can cause sudden collapse of

nd drift is within the limit

storey at ground floor or no infills at this level


-storey (M-3) it is

3) it is 3.2mm only which is 7.06 times more than the


icularly at this level by putting stiffed column, core shear wall or bracing if needed to

7 it means soft-storey at

3 model which shows that when we

storey at upper level the sudden displacement come done with respect to M-3 model

but it is beyond the limit of safety, so such type of building also need safety measures as

direction.


storey. From the table drift is 12.3mm for M-3 at first

2 model. This shows that there is no sudden change in the


7 plotted graphically with respect


storey building this may hamper the integrity of

he structure and causes serious loss of life and properties in case of major earthquake, so

20

Storey Drift Y-Direction

M-1

M-2

M-3

M-4

M-5

M-6

M-7


http://www.iaeme.com/IJCIET/index.asp 120 [email protected]

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[2] Arlekar, J. N., Jain, S. K. & Murty, C. Seismic Response of RC Frame Buildings with Soft

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[3] Arora, A. Alternative Approach to Soft Storey in Seismic Analysis of R.C.C Building

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effects of drift in soft storied rcc - … · limits under zones- iii by etabs respect to bare and...

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