EFFECT OF HAUNCHED BEAMS IN MOMENT RESISTING RC …Reinforced concrete (RC) Haunched beams are widely used as bridges or portal frames and precast roof girders, there is a lack of

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International Journal of Civil Engineering and Technology (IJCIET)

Volume 8, Issue 9, September 2017, pp. 1187–1199, Article ID: IJCIET_08_09_134

Available online at http://http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=8&IType=9

ISSN Print: 0976-6308 and ISSN Online: 0976-6316

© IAEME Publication Scopus Indexed

EFFECT OF HAUNCHED BEAMS IN MOMENT

RESISTING RC FRAMES

Venna Mythilee Priyanka

Department of Civil Engineering,

Andhra University, Visakhapatnam, India

M. Pavan Kumar


SVP Engineering College, Visakhapatnam, India

Dr. G.V.S. Raj Kumar

Department of IT,

GITAM University, Visakhapatnam, India

Duba Vishalakshi


Govt Polytechnic, Visakhapatnam, India

ABSTRACT

The need of experimental studies on the motorized behavior of reinforced concrete

(RC) Haunched beams leads to difficulties in statistical and reliability analysis. This

study performs the analysis of RC framed structure with Haunched beams. Structures

composed of Haunched beams, have been recently adopted for many high-rise

buildings. STAAD pro has been used for the analysis of RC framed structure with

Haunched beams. This paper is concerned with the effects of stiffness attained by

considering Haunched beams on the seismic response of a structure and the main

objective is to carry out the linear static (seismic coefficient) and linear dynamic

(response spectrum) analysis on RC building frames modelled with and without

Haunched beams for ten storeys at all seismic zones in India considering IS 1893

(Part 1): 2002 and compare the results of analysis (lateral displacements and natural

period). From the results analysis, it was observed that there is an increase in the

stiffness of RC frame with Haunched beams than that of the RC frame without

Haunched beams.

Key words: Haunched beams, Stiffness, RC frames, Lateral displacement, STAAD

pro.

Cite this Article: Venna Mythilee Priyanka, M. Pavan Kumar, Dr. G.V.S. Raj Kumar,

Duba Vishalakshi. Effect of Haunched Beams in Moment Resisting RC Frames.

International Journal of Civil Engineering and Technology, 8(9), 2017, pp. 1187–

1199.

http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=9

Effect of Haunched Beams in Moment Resisting RC Frames


1. INTRODUCTION

Haunched beam is a beam whose cross section is thicker at the supports than in the middle of

the span. Haunched beams are used in buildings for many reasons among them as they favor a

more efficient use of materials to clear a given span or to provide a reasonable clear height for

the storeys of buildings. Indeed, tapered elements in general and Haunched beams in

particular have been traditionally difficult to model in a practical manner. This was the main

reason for which most commercial software did not include them in their elements libraries

for many years. In fact, it was in 2000’s the leading worldwide commercial software for

structural analysis such as STAAD pro started to include them in their element libraries.

Reinforced concrete (RC) Haunched beams are widely used as bridges or portal frames

and precast roof girders, there is a lack of studies in the literature investigating this topic

Scarce in experimental studies is the main obstacle to include this topic in details by

international building practice codes. As a result of various experimental studies (Nilson, et

al. 2011), it can be concluded that the behavior and failure of the RC Haunched beams differs

as compared to prismatic section RC beams. The researchers (Tena colunga, 2012) ,

(Archundia-Aranda, et al. 2013) proved that the depth variance along the beam has a clear

influence on the shear behaviour as well as shear capacity (Albegmprli, et al. 2015).

During an earthquake, failure of structure starts at points of weakness. This weakness

arises due to discontinuity in mass, stiffness and geometry of structure. The structures having

this discontinuity are termed as irregular structures. Irregular structures contribute a large

portion of urban infrastructure. Irregularities are one of the major reasons of failures of

structures during earthquakes. For example structures with soft storey were the most notable

structures which collapsed. So, the effect of irregularities in the seismic performance of

structures becomes really important. Height-wise changes in stiffness and mass render the

dynamic characteristics of these buildings different from the 'regular' building. According to

IS 1893: 2002, structure withstand moderate level of earthquake ground motion without

structural damage, but possibly with some structural as well as non-structural damage. In

present study, the earthquake analysis for ten storeyed buildings was done by both linear

static analysis and linear dynamic (Response Spectrum) analysis.

2. METHODOLOGY

The plan and elevation of ten storeyed reinforced concrete buildings with and without

considering Haunched beams are shown in the fig 1& fig 2.

Figure 1 Plan of the RC framed structure (All dimensions in m)

Venna Mythilee Priyanka, M. Pavan Kumar, Dr. G.V.S. Raj Kumar, Duba Vishalakshi


Figure 2 Elevation of 10 storeyed RC Framed Structure

2.1. Geometrical Configuration

Ten storeyed reinforced concrete buildings which are modelled without Haunched beams and

with Haunched beams are considered. Figure shows the plan of the three buildings. Storey

height of each building is assumed as 3.0m. Fig 3 shows the column positions of the RC

building. Fig 4 and Fig 5 shows the 3D rendered view of RC frames without Haunched beams

and RC frames with Haunched beams.

Beam cross sections for ten storeyed RC model at seismic zone II, III, IV and V – 230 mm

x 630 mm. Column cross sections for ten storeyed RC model at seismic zone II, III, IV and V

– 380 mm x 750 mm. Beam Cross section for Haunched beam1: The width of the Haunched

beam is constant that is 230 mm and the depth of the beam is varies from 400 mm to 630

mm.Beam Cross section for Haunched beam2: The width of the Haunched beam is constant

that is 230 mm and the depth of the beam is varies from 630 mm to 830 mm.

2.2. 3D views of the RC Framed Structures used for Analysis

Figure 3 3D view of the RC frame structure without Haunched beams



Figure 4 3D view of the RC frame structure with Haunched beam1

Figure 5 3D view of the RC frame structure with Haunched beam2

2.3. Structural Analysis and Design

The steps required to analyse and design a structure using STAAD Pro V8i are represented by

a flow chart as shown below:

Figure 6 Flow chart showing Methodology of the Present Study



3. RESULTS & DISCUSSIONS

The results for linear static and linear dynamic analysis are calculated. The results are given

for Mode number & natural period, lateral displacements and base shear of the RC frames

with and without Haunched beams for ten storeys RC framed structure for seismic zones II,

III, IV & V respectively.

3.1. Linear Static Analysis

The analysis for load combinations is carried out for positive and negative X & Z directions

after defining the seismic definition. The corresponding lateral displacements at each and

every storey height from the ground level for the three models (RF, RFHB1 & RFHB2) with

and without Haunched beams for the seismic zones II, III, IV & V are compared below.

Case (i) Regular Frame (RF)

Table 1 Lateral displacements of RF

Storey Height

(m)

Lateral Displacement (mm)

ZONE-II ZONE-III ZONE-IV ZONE-V

32 47.236 75.787 113.855 170.957

29 46.126 73.785 110.664 165.981

26 43.568 69.704 104.553 156.826

23 40.089 64.139 96.206 144.308

20 35.865 57.38 86.067 129.098

17 31.072 49.71 74.561 111.839

14 25.87 41.38 62.076 93.109

11 20.397 32.63 48.941 73.408

8 14.758 23.612 35.416 53.122

5 9.082 11.639 21.586 32.303

2 2.522 3.935 5.819 8.645

Case (ii) Regular Frame with Haunched Beam1 (RFHB1)

Table 2 Lateral displacements of RFHB1

Storey

Height (m)

Lateral Displacement (mm)


32 41.478 65.11 96.62 143.884

29 40.336 63.265 93.837 139.694

26 38.037 59.727 88.647 132.028

23 34.983 54.971 81.622 121.598

20 31.319 49.241 73.136 108.98

17 27.194 42.777 63.554 94.72

14 22.744 35.797 53.202 79.309

11 18.086 28.491 42.365 63.176

8 13.308 21.004 31.266 46.659

5 8.499 13.405 19.946 29.758

2 2.477 3.856 5.693 8.45



Case (iii) Regular Frame with Haunched Beam2 (RFHB2)


Storey Height (m) Lateral Displacement (mm)


32 24.805 39.521 59.142 88.57

29 24.221 38.498 57.535 86.89

26 22.925 36.443 54.468 81.505

23 21.192 33.688 50.35 75.343

20 19.122 30.396 45.427 67.975

17 16.805 26.711 39.918 59.729

14 14.32 22.759 34.012 50.89

11 11.734 18.65 27.871 41.702

8 9.1 14.469 21.628 32.367

5 6.45 10.233 15.277 22.844

2 2.086 3.261 4.828 7.179

Comparison of Lateral Displacement for RF, RFHB1 & RFHB2

Figure 7 Comparison of Lateral Displacement of RC frame with and without Haunched Beams

(RFHB1, RFHB2) at seismic Zone-II obtained by Linear Static Analysis.

Figure 8 Comparison of Lateral Displacement of RC frame with and without Haunched beams

(RFHB1, RFHB2) at seismic Zone-III obtained by Linear Static Analysis.

0

10

20

30

40

50

0 4 8 12 16 20 24 28 32

La

tera

l D

isp

lace

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t

(mm

)

Height (meters)

RF

RFHB1

RFHB2

0

20

40

60

80

100

0 4 8 12 16 20 24 28 32

La

tera

l D

isp

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t (m

m)

Height (meters)




(RFHB1, RFHB2) at seismic Zone-IV obtained by Linear Static Analysis.


(RFHB1, RFHB2) at seismic Zone-V obtained by Linear Static Analysis.

From the above figures 7, 8, 9 and 10, it is observed that there was a decrease in lateral

displacement of RC frame with Haunched beams (RFHB1& RFHB2) when compared to the

RC frame without Haunched beams. The percentage of decrease in the lateral displacements

of the RC frames with Haunched beams for RFHB1 & RFHB2 at seismic zone II & III are

12% and 47, seismic zone IV & V are 15% and 48% respectively when compared with

regular frame without Haunched beams.

3.2. Linear Dynamic Analysis

The analysis for load combinations is carried out for positive X & Z directions after defining

the Response Spectrum load case. The corresponding lateral displacements and base shear at

each and every storey height from the ground level and the natural period with respect to

modes for the three models (RF, RFHB1& RFHB2) with and without Haunched beams for

the seismic zones II, III, IV & V are compared below.

0

20

40

60

80

100

120

140

0 4 8 12 16 20 24 28 32L

ate

ra

l D

isp

lace

men

t

(mm

)

Height (meters)

020406080

100120140160180200

0 4 8 12 16 20 24 28 32

La

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isp

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men

t

(mm

)

Height (meters)



Case (i) :Regular Frame Lateral isplacements

Table 4 Lateral displacements of Regular Frame


Zone-II Zone-III Zone-IV Zone-V

32 81.524 130.648 196.147 294.396

29 80.376 128.585 192.863 289.281

26 77.157 123.447 185.168 277.748

23 72.313 115.698 173.545 260.315

20 65.97 105.548 158.319 237.475

17 58.275 93.235 139.849 209.77

14 49.41 79.05 118.571 177.852

11 39.578 63.32 94.976 142.46

8 28.99 46.383 69.572 104.357

5 17.818 28.418 42.552 63.752

2 4.839 7.642 11.38 16.986

Case(ii): Regular Frame with Haunched Beam1


Case (iii): Regular Frame with Haunched Beam2




32 69.155 109.394 163.045 243.521

29 68.069 107.638 160.397 239.535

26 65.273 103.304 154.013 230.076

23 61.175 96.878 144.482 215.888

20 55.881 88.54 132.085 197.404

17 49.512 78.485 117.116 175.063

14 42.213 66.948 99.928 149.398

11 34.154 54.2 80.928 121.02

8 25.505 40.519 60.538 90.567

5 16.375 26.007 38.849 58.112

2 4.702 7.416 11.034 16.461



32 42.929 68.519 102.639 153.816

29 42.43 67.633 101.238 151.641

26 40.889 65.186 97.582 146.117

23 38.608 61.555 92.15 138.04

20 35.646 56.834 85.084 127.458

17 32.063 51.123 76.536 114.654

14 27.935 44.543 66.687 99.901

11 23.348 37.232 55.744 83.51

8 18.396 29.342 43.938 65.831

5 13.099 20.871 31.234 46.777

2 4.165 6.587 9.817 14.661



020406080

100120140160180200

0 4 8 12 16 20 24 28 32

La

tera

l

Dis

pla

cem

ent(

mm

)

Height (meters)

Comparison of Lateral Displacement for RF, RFHB1 & RFHB2


(RFHB1, RFHB2) at seismic Zone-II obtained by Linear Dynamic Analysis.


(RFHB1, RFHB2) at seismic Zone-III obtained by Linear Dynamic Analysis.


(RFHB1, RFHB2) at seismic Zone-IV obtained by Linear Dynamic Analysis.

0

10

20

30

40

50

60

70

80

90

100

0 4 8 12 16 20 24 28 32

La

tera

l D

isp

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men

t(m

m)

Height (meters)

0102030405060708090

100110120130140150

0 4 8 12 16 20 24 28 32

La

tera

l

Dis

pla

cem

ent(

mm

)

Height (meters)



020406080

100120140160180200220240260280300

0 4 8 12 16 20 24 28 32

La

tera

l

Dis

pla

cem

ent(

mm

)

Height (meters)


(RFHB1, RFHB2) at seismic Zone-V obtained by Linear Dynamic Analysis.

From the Figures 11, 12, 13 and 14, it is observed that there was a decrease in lateral

displacement of RC frame with Haunched beams (RFHB1&RFHB2) when compared to the

RC frame without Haunched beams. The percentage of decrease in the lateral displacements

of the RC frames with Haunched beams for RFHB1 & RFHB2 at seismic zone II are 15% and

47%, seismic zone III & IV are 16% and 47% , seismic Zone-V are 17% and 47%

respectively when compared regular frame without Haunched beams.

3.3. Natural Period and Frequency

The Natural period and frequency for a Regular Frame(RF), Regular frame with Haunched

beam1(RFHB1) and Regular frame with Haunched beam2(RFHB2) at each mode are given

below. Table 7 Frequency and time period for mode shapes

Mode

RF RFHB1 RFHB2

Frequency

Hz

Period

seconds

Frequency

Hz

Period

seconds

Frequency

Hz

Period

seconds

1 0.291 3.432 0.355 2.818 0.431 2.318

2 0.317 3.155 0.389 2.57 0.489 2.044

3 0.329 3.041 0.399 2.508 0.509 1.963

4 0.389 2.568 0.596 1.677 0.719 1.392

5 0.477 2.095 0.791 1.264 0.951 1.052

6 0.477 2.095 0.795 1.258 0.959 1.043

Comparison of natural period of RC frame with and without Haunched beams

Figure 15 Comparison of natural period of RC frame with and without Haunched beams (RFHB1,

RFHB2)

00.5

11.5

22.5

33.5

4

1 2 3 4 5 6

PER

IOD

(Se

c)

MODE

RF

RFHB1

RFHB2



The percentage of decrease in the natural period of the RC frameswith Haunched beams1

for the Mode numbers 1, 2, 3, 4, 5 & 6 are 17%, 18%, 17%, 34%, 39% & 40% respectively

when compared regular frame.

The percentage of decrease in the natural period of the RC frames with Haunched beam2

for the Mode numbers 1, 2, 3, 4, 5 & 6 are32%, 35%, 35%, 34%, 39% & 40% respectively

when compared regular frame.

3.4. Base Shear

The base shear of a Regular frame with Haunched beam1 at each and every storey height

from the ground level with respect to all zones are given below

Table 8 Base Shear of Regular frame

HEIGHT BASE SHEAR (KN)


32 255.82 409.31 613.96 920.94

29 645.21 1032.33 1548.5 2322.75

26 978.28 1565.25 2347.87 3521.81

23 1289.55 2063.28 3094.92 4642.38

20 1571.33 2514.13 3771.2 5656.8

17 1817.48 2907.97 4361.96 6542.94

14 2022.66 3236.25 4854.37 7281.56

11 2182.52 3492.04 5238.05 7857.08

8 2294.6 3671.36 5507.04 8260.56

5 2346.14 3753.83 5630.74 8446.11

2 2349.9 3759.84 5639.75 8459.62

Table 9 Base Shear of RFHB1



32 278.36 445.37 668.05 1102.08

29 740.14 1184.22 1776.33 2664.49

26 1124.86 1799.78 2699.67 4049.51

23 1486.36 2378.17 3567.26 5350.88

20 1815.6 2904.95 4357.43 6536.14

17 2105.84 3369.34 5054.02 7581.02

14 2351.11 3761.77 5642.66 8463.98

11 2546.33 4074.13 6111.2 9166.8

8 2688.4 4301.44 6452.15 9678.23

5 2752.84 4404.54 6606.81 9910.21

2 2759.07 4414.51 6621.76 9932.64

Table 10 Base Shear of RFHB2



32 302.72 484.36 726.54 1089.81

29 759.14 1214.62 1821.93 2732.9

26 1155.08 1848.13 2772.19 4158.29

23 1528.98 2446.37 3669.56 5504.33

20 1872.95 2996.72 4495.08 6742.62

17 2180.94 3489.51 5234.26 7851.39

14 2447.57 3916.11 5874.16 8811.24

11 2668.17 4269.07 6403.62 9605.42

8 2839.77 4543.64 6815.46 10223.19

5 2931.79 4690.86 7036.3 10554.45

2 2940.45 4704.71 7057.08 10585.61



From the above, it was observed that there was an increase in Base Shear of RC frame

with Haunched beams (RFHB1&RFHB2) when compared to the RC frame without Haunched

beams. The percentage of increase in the Base Shear of the RC frames with Haunched beams

for RFHB1& RFHB2 at all seismic Zones are 17% and 25% respectively when compared

with regular frame without Haunched beams.

4. CONCLUSIONS

The analysis of RC frames with and without Haunched beams has been carried out for ten

storeyed model at all seismic zones in India as per code IS: 1893:2002 by using linear static

analysis and linear dynamic analysis. Based on the analysis of results and discussions thereon

the following conclusions are shown

For ten storeyed regular RC frames, it was observed that there was an increase in lateral

displacement of RC frame at seismic Zones III, IV & V are 37%, 58% and 72% respectively

by linear static analysis and 37%, 58% and 72% respectively by linear dynamic analysis with

respect to seismic Zone II.

For ten storeyed regular RC frame with Haunched beam1, it was observed that there was an

increase in lateral displacement of RC frame at seismic Zones III; IV & V are 36%, 57% and

71% respectively by linear static analysis and 36%, 58% and 71% respectively by linear

dynamic analysis with respect to Zone II.

For ten storeyed regular RC frame with Haunched beam2, it was observed that there was an

increase in lateral displacement of RC frame at seismic Zones III, IV & V are are 37%, 58%

and 71% respectively by linear static analysis and 37%, 58% and 72% respectively by linear

dynamic analysis with respect to Zone II.

For RC frame with Haunched beam1, it was observed that there was a decrease in lateral

displacement when compared to the regular RC frame are 12%, 14%, 15% and 15%

respectively by linear static analysis and 15%, 16% ,16 % and 17% respectively by linear

dynamic analysis with respect to seismic Zones II, III, IV & V.

For RC frame with Haunched beam2, it was observed that there was a decrease in lateral

displacement when compared to the regular RC frame are 47%, 47%,48% and 48%

respectively by linear static analysis and 47%, 47% ,47 % and 47% respectively by linear

dynamic analysis with respect to seismic Zones II, III, IV & V.

From the results of a ten storeyed RC frame with Haunched beam1, it was observed that there

is a decrease in the natural period of the frame with Haunched beams when compared to the

frame without Haunched beams are 17%, 18%, 17%, 34%, 39% & 40% for the mode numbers

1, 2, 3, 4, 5 & 6 respectively.

From the results of a ten storeyed RC frame with Haunched beam2, it was observed that there

is a decrease in the natural period of the frame with Haunched beams when compared to the

frame without Haunched beams are 32%, 35%, 35%, 34%, 39% & 40% for the mode numbers

1, 2, 3, 4, 5 & 6 respectively.

From the results, it was observed that there was an increase in Base shear of RC frame with

Haunched beams (RFHB1&RFHB2) when compared to the RC frame without Haunched

beams. The percentage of an increase in the Base shear of the RC frames with Haunched

beams for RFHB1& RFHB2 are 17% and 25% respectively.

In view of the above observations, clearly there was an increase in the stiffness for RC frame

with Haunched beam1 compared with the regular RC frame and there was an increase in the

stiffness for RC frame with Haunched beam2 compared with the RC frame with Haunched

beam1. Thus, by considering Haunched beams, effective stiffness models can be generated.



REFERENCES

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analysis of reinforced concrete haunched beams shear capacity based on stochastic

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[2] Archundia-Aranda, H.I. Tena-Colunga, A. and Grande-Vega, A (2013) “Behavior of

reinforced concrete Haunched beams subjected to cyclic shear loading”, Engineering

Structures journal, Volume 49,pp. 27-42.

[3] Abd el-rahman megahid, Rashwan M. M. and Ahmed mohamed sayed ( 2010) “Static

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[10] Rombach,G. and Nghiep, V.H. (2011), “Shear strength of Haunched concrete beams

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[13] Vu Hong Nghiep (2011) “Shear Design of Straight and Haunched Concrete Beams

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EFFECT OF HAUNCHED BEAMS IN MOMENT RESISTING RC …Reinforced concrete (RC) Haunched beams are widely used as bridges or portal frames and precast roof girders, there is a lack of