Response of Building for Different Braces using E-TABS

DOI : 10.17577/IJERTCONV10IS11060

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Response of Building for Different Braces using E-TABS

Namrata S Naragunkar, Sushma, Sinchana M B, Shwetha K M, Ranjitha P

Department of Civil Engineering,

Jain Institute of Technology, Davangere, India

AbstractIndia is developing country, Nowadays our Indian population is increasing day by day. According to some sources our Indian population is reached nearly 138 cores, this rapid increase in population forced engineers to adopt for high rise building. Damage caused by lateral load is need to be control. There are so many methods to control the damage of building by lateral loads, we are adopting one of method, providing the different types of bracings to the building.

In present study, we have used conventional building with 16mx10m along X and Y direction. We carried out the equivalent static linear analysis by using ETABS software, then comparing the results of displacement, storey drift, base shear b\w the bare building and Braced building.

KeywordsBracing, Displacements, Storey Drift, Base shear, E- TABS etc.

I.INTRODUCTION

India is developing country. According to 2020census our Indian population is reached nearly 138,00,00,4385(138 corers). This sudden increase in population and low availability of the land have forced us (engineers) to go for high rise building. Tall building or high rise building are exposed to various forces or load due to various forces the displacement and moments are generated. To avoid these problems we are chosen.

Bracings, to observe the vibrations the devices or any material are placed which is called as Bracings. There are many ways to providing bracings to improve the building performance. There are different types of bracings namely Diagonal Bracing, V Bracing, Inverted V Bracing and X Bracing. The primary function of Bracing is to provide stability and resist lateral load either from diagonal steel members or from concrete core. For bracing frame, to only support vertical loads beams and columns are designed since all the lateral loads are carried by bracings systems. A braced frame is really strong structure subject to lateral load and wind load, frame are generally made by steel structure, which can work effectively both tension and compression.

    1. Different types of Bracings

      A braced frame is a really strong structural system commonly used in structures subject to lateral loads such as wind and seismic pressure. The members in braced frame are generally made of steel structures and RCC structures which can work effectively both in tension and compression.

      Types of bracing system used as follow:

      • Diagonal Bracing

      • V Bracing

      • Inverted V Bracing

  • X Bracing

  • Diagonal Bracing: structural component of any building just above it is a diagonal bracing. To add a strength wooden case member or crate member placed in adjacent angle.

  • V Bracing: Two Diagonal members forming a V shape extend downwards from the top two corners of a horizontal members and meet at a centre point on the lower horizontal member its known as V Bracing.

  • Inverted V Bracing: Inverted v bracing are also know as chevron bracing. Two diagonal members forming a V shape extended upwards from the bottom two corners of a horizontal members and meet at a centre point on the upper horizontal member its know as Inverted V Bracing

  • X Bracing: X bracing uses two diagonal members crossing each other. These only need to be resist to tension, one brace at a time acting to resist sideways forces, depending on the direction of loading. As a result, steel cables can also be used for cross- bracing.

    II. OBJECTIVE

    In this project G+11 story RCC structure is analyzed to reduce the displacement and movement of the structure.

    • To compare the response of high rise building, with and with and without bracing.

    • To determine the displacement, story drift and base shear for bare building.

    • To determine the displacement, story drift and base shear after introduction of the bracing.

    • To analyze the structure for different orientation of column and compare their results.

    • To select the best bracing among Diagonal Bracing, Inverted V Bracing, V Bracing and X Bracing. Types of structure analyzed:

III.METHADOLOGY

    1. Step by step as per the below procedure:

      • After the study of various literature reviews, we found our project objectives.

      • In this project we are considering G+ 11 stories. The building dimension 16mx10m.

        • Comparing strength and stability of bare building with the braced building.

        • Analyse all models using E-tabs software by applying the selected loads on building as per the IS code book (IS 875).

    2. GEOMETRICAL DATA:

      • Number of stories: G+11

      • Type of building use: Commercial

      • Plane dimension: 16m x 10m

      • Typical story height: 3m

      • Bottom story height: 3m

      • Height of structure: 36m

    3. MATERIALS USED:

      • Grade of concrete: M25 for slab, M30 for beams and columns.

      • Grade of steel: Fe500

      • Grade of bracing: ISMB500

    4. LOADING DATA:

      • Dead load:It is defined automatically by software (Table 2, IS875 (part 1) ; 1987)

      • Live load:For commercial building as per (Table, IS875 (part-2), live load is taken as 2KN/m2.

      • Floor finish: 1.5KN/m2.

      • Wall load: 12.42KN\m.

    5. MODELING AND STRUCTURE

Fig 1: Plan of the model

Fig-2 Unbraced building (3D view)

FIG-3 X Bracing (3D view)

Fig-4 V Bracing (3D view)

Fig-5 Inverted v bracing (3D view)

Fig-6 Diagonal bracing (3D view)

  1. RESULT AND DISCUSSION

      1. Maximum storey displacement with 1.5(DL+LL+EQX) along X direction.

        story

        Bare building

        Diagonal bracing

        V

        Bracing

        Inverted V

        X

        Bracing

        Base

        0

        0

        0

        0

        0

        Story1

        2.603

        1.386

        1.28

        0.988

        0.935

        Story2

        7.386

        3.493

        3.455

        2.793

        2.645

        Story3

        12.749

        5.957

        5.951

        4.978

        4.823

        Story4

        18.247

        8.687

        8.731

        7.508

        7.353

        Story5

        23.705

        11.581

        11.67

        10.264

        10.111

        Story6

        29.008

        14.545

        14.673

        13.135

        12.983

        Story7

        34.046

        17.496

        17.651

        16.026

        15.868

        Story8

        38.698

        20.357

        20.52

        18.85

        18.673

        Story9

        42.828

        23.058

        23.202

        21.538

        21.317

        Story10

        46.278

        25.556

        25.626

        24.027

        23.724

        Story11

        48.843

        27.797

        27.737

        26.298

        25.863

        Story12

        50.255

        29.64

        29.397

        28.25

        27.563

        Table-1 Maximum storey displacement in X- direction

        Fig-7 Maximum storey displacement of the building along X direction.

        According to the above graph, bare building shows maximum displacement compare to different braced building in X direction.

        Diagonal bracing shows 41.02% lesser displacement then the Bare building. V Bracing shows 41.50% lesser displacement than the bare building. Inverted V Bracing shows 43.78% lesser displacement than the bare building. X bracing shows 45.15% displacement. when compared with other bracings X bracing shows least displacement and more stable.

      2. Maximum storey displacement 1.5(DL+LL+EQY) along y- direction

        displacement compared to the bare building. V Bracing shows 31.13% lesser displacement compared to the bare building. Inverted V Bracing shows 32.74% lesser displacement compared to the bare building. X Bracing shows 33.07% lesser displacement.

      3. Maximum storey drift 1.5(DL+LL+EQX) in X direction.

        Story

        Bare building

        Diagonal Bracing

        V

        Bracing

        X

        Bracing

        inverted v

        Base

        0

        0

        0

        0

        0

        Story1

        0.000868

        0.000427

        0.000453

        0.000329

        0.000312

        Story2

        0.001594

        0.000727

        0.000704

        0.000602

        0.00057

        Story3

        0.001788

        0.000844

        0.000822

        0.000733

        0.000726

        Story4

        0.001833

        0.000934

        0.000911

        0.000849

        0.000844

        Story5

        0.00182

        0.000986

        0.000965

        0.000924

        0.00092

        Story6

        0.001768

        0.001007

        0.000989

        0.000963

        0.000958

        Story7

        0.001679

        0.000999

        0.000985

        0.000969

        0.000962

        Story8

        0.001551

        0.000963

        0.000955

        0.000947

        0.000935

        Story9

        0.001377

        0.000902

        0.000903

        0.000901

        0.000882

        Story10

        0.001151

        0.000819

        0.000833

        0.000838

        0.000806

        Story11

        0.000856

        0.000723

        0.000754

        0.000768

        0.000716

        Story12

        0.000471

        0.000553

        0.000615

        0.00065

        0.000567

        Table-3 Max storey drift of the building in X direction.

        4.3

        Story

        Bare Building

        Diagonal Bracing

        V

        Bracing

        Inverted Bracing

        X

        Bracing

        Base

        0

        0

        0

        0

        0

        Story1

        2.659

        1.748

        1.322

        1.258

        1.321

        Story2

        7.658

        4.573

        3.751

        3.606

        3.869

        Story3

        13.37

        7.885

        6.732

        6.575

        6.913

        Story4

        19.291

        11.534

        10.161

        9.988

        10.343

        Story5

        25.216

        15.389

        13.874

        13.686

        14.013

        Story6

        31.015

        19.329

        17.727

        17.523

        17.796

        Story7

        36.565

        23.244

        21.593

        21.368

        21.574

        Story8

        41.731

        27.032

        25.359

        25.102

        25.236

        Story9

        46.358

        30.599

        28.928

        28.617

        28.677

        Story10

        50.24

        33.872

        32.221

        31.817

        31.797

        Story11

        53.027

        36.729

        35.153

        34.574

        34.475

        Story12

        54.574

        38.986

        37.585

        36.705

        36.522

        Table -2 Maximum storey displacement of the building along Y- direction.

        Fig-8 Maximum storey displacement of the building along Y- direction.

        According to above graph, bare building shows maximum displacement compare to different braced building in Y direction. Diagonal Bracing shows 28.56% lesser

        Fig- 9 maximum storey drift of the building in X- direction According to above graph, bare building shows maximum drift compare to different braced building in X direction. Diagonal bracing shows 45.06% lesser drift compared to the bare building. V Bracing shows 46.04% lesser drift compared to the Bare building. V Bracing shows 47% lesser drift compared to the bare building. X Bracing shows 47.67% lesser drift when compared to other bracings.

      4. Maximum storey drift 1.5(DL+LL+EQY) in Y direction.

        Story

        Bare Building

        Diagonal Bracing

        V

        Bracing

        Inverted V

        Bracing

        X

        bracing

        Base

        0

        0

        0

        0

        0

        Story1

        0.00088

        0.00057

        0.00044

        0.00041

        0.0004

        Story2

        0.00166

        0.00094

        0.0008

        0.00078

        0.0008

        Story3

        0.00190

        0.00110

        0.001

        0.0009

        0.0010

        Story4

        0.00197

        0.00121

        0.00114

        0.00113

        0.0011

        Story5

        0.00197

        0.00128

        0.00124

        0.00123

        0.0012

        Story6

        0.00193

        0.00131

        0.00128

        0.00128

        0.0012

        Story7

        0.0018

        0.00130

        0.00129

        0.00129

        0.0012

        Story8

        0.00172

        0.00126

        0.0012

        0.00125

        0.0012

        Story9

        0.00154

        0.00119

        0.00119

        0.0011

        0.0011

        Story10

        0.00129

        0.00109

        0.00110

        0.0010

        0.0010

        Story11

        0.0009

        0.00095

        0.00098

        0.00093

        0.0009

        Story12

        0.00051

        0.000752

        0.00081

        0.00073

        0.0006

        Table -4 Maximum storey drift of the building in y- direction.

        Fig-10 Maximum storey drift of the building in y- direction.

        According to above graph, bare building shows maximum drift compare to different braced building in Y direction. Diagonal Bracing shows 33.4% lesser drift, V Bracing shows 34.5% lesser drift, Inverted V Bracing shows 34.7% lesser drift and X Bracing shows 36% lesser drift when compared to the bare building.

        Bracings

        Fx

        Fy

        Fz

        Mx

        My

        without

        -120.8

        -312

        56974.96

        2.93E+08

        -515781

        Diagonal

        -1863.5

        -312

        58215.8

        298795

        -543245

        V Bracing

        -2023.8

        -312

        58764.85

        301540

        -552053

        Inverted V

        -1899.8

        -312

        58764.88

        301540

        -548848

        X bracing

        -2044.0

        -312

        59457.43

        305703

        -558459

      5. Base Shear 1.5(DL+LL+EQX) in X- direction: Table : 5 Base shear for different braced building.

        Fig: 11 Base shear for different braced building.

        The Base shear of the bare building is minimum when compared with braced building. Among the all types of bracing X Bracing shows maximum Base shear.

        Bracings

        Fz

        Mx

        My

        without

        56974.17

        294745.7

        -492620

        Diagonal

        58215.8

        300953.9

        -503174

        V Bracing

        58764.88

        303699.3

        -507841

        Inverted V

        58764.88

        303699.3

        -507841

        X bracing

        59457.43

        307162.1

        -513728

      6. Base shear 1.5(DL+LL+EQY) along Y direction. Table :6 Base shear for different braced building.

        Fig : 12 Base shear for different braced building.

        The Base shear of the bare building is minimum when compared with braced building. Among the all types of bracing X Bracing shows maximum Base shear.

      7. Lateral displacement due to Wind Load 1.5(DL+LL+WX) along X direction

        Table: 7 Lateral displacement due to wind load along X direction

        Story

        Bare building

        Diagonal bracing

        V

        Bracing

        Inverted V

        X

        bracing

        mm

        mm

        mm

        mm

        mm

        Base

        0

        0

        0

        0

        0

        Story1

        0.643

        0.223

        0.148

        0.14

        0.0546

        Story2

        1.776

        0.549

        0.479

        0.394

        0.15366

        Story3

        3.032

        0.934

        0.794

        0.709

        0.27651

        Story4

        4.335

        1.371

        1.169

        1.087

        0.42393

        Story5

        5.665

        1.85

        1.591

        1.514

        0.59046

        Story6

        7.013

        2.36

        2.05

        1.978

        0.77142

        Story7

        8.374

        2.893

        2.535

        2.47

        0.9633

        Story8

        9.744

        3.443

        3.037

        2.979

        1.16181

        Story9

        11.111

        4.001

        3.547

        3.497

        1.36383

        Story10

        12.446

        4.567

        4.054

        4.013

        1.56507

        Story11

        13.63

        5.121

        4.558

        4.528

        1.76592

        Story12

        14.304

        5.569

        4.994

        4.928

        1.92192

        Fig :13 Shows the lateral displacement due to wind load along X direction.

        According to the above graph, bare building shows maximum displacement compare to different braced building in X direction.

        Diagonal bracing shows 61% lesser displacement then the Bare building. V Bracing shows 65.08% lesser displacement than the bare building. Inverted V Bracing shows 65.54% lesser displacement than the bare building. X bracing shows 80.05% displacement. when compared with other bracings X bracing shows least displacement and more stable.

      8. Lateral displacement due to Wind load 1.5(DL+LL+WY) along Y direction.

    Table:8 Lateral displacement due to Wind load along Y direction.

    Story7

    0.000454

    0.000178

    0.000107

    0.000167

    0.000166

    Story8

    0.000457

    0.000183

    0.000128

    0.000173

    0.000172

    Story9

    0.000456

    0.000187

    0.000147

    0.000176

    0.000175

    Story10

    0.000445

    0.000189

    0.000164

    0.000177

    0.000176

    Story11

    0.000396

    0.000191

    0.00018

    0.000179

    0.000175

    Story12

    0.000225

    0.000149

    0.00014

    0.000146

    0.000133

    Story

    Bare building

    Diagonal bracing

    V

    bracing

    Inverted V

    X

    bracing

    mm

    mm

    mm

    mm

    mm

    Base

    0

    0

    0

    0

    0

    Story1

    0.926

    0.45

    0.323

    0.315

    0.085

    Story2

    2.5

    1.101

    0.902

    0.827

    0.34

    Story3

    4.261

    1.865

    1.547

    1.469

    0.761

    Story4

    6.103

    2.725

    2.31

    2.229

    1.339

    Story5

    7.994

    3.66

    3.161

    3.078

    2.042

    Story6

    9.92

    4.65

    4.076

    3.995

    <>2.846

    Story7

    11.869

    5.678

    5.034

    4.957

    3.731

    Story8

    13.829

    6.729

    6.017

    5.947

    4.679

    Story9

    15.772

    7.787

    7.006

    6.946

    5.671

    Story10

    17.608

    8.834

    7.981

    7.934

    6.68

    Story11

    19.033

    9.784

    8.877

    8.823

    7.603

    Story12

    19.739

    10.467

    9.574

    9.439

    8.247

    Fig:15 shows the story drift due to wind load along X direction

    According to above graph, bare building shows maximum drift compare to different braced building in X direction. Diagonal bracing shows 58.64% lesser drift compared to the bare building. V Bracing shows 60.61% lesser drift compared to the Bare building. V Bracing shows 60.83% lesser drift compared to the bare building. X Bracing shows 62% lesser drift when compared to other bracings.

      1. Story drift due to Wind load 1.5(DL+LL+WY) along Y direction.

        Fig:14 Shows the displacement along Y direction due to Wind load

        According to above graph, bare building shows maximum displacement compare to different braced building in Y direction. Diagonal Bracing shows 46.97% lesser displacement compared to the bare building. V Bracing shows 51.49% lesser displacement compared to the bare building. Inverted V Bracing shows 52.18% lesser displacement compared to the bare building. X Bracing shows 58.21% lesser displacement.

        4.9 Storey Drift due to Wind load 1.5(DL+LL+WX) along X direction.

        Story

        Bare building

        Diagonal bracing

        Vbracing

        Inverted V

        X bracing

        Base

        0

        0

        0

        0

        0

        Story1

        0.000214

        0.000073

        0.000101

        0.000049

        0.000047

        Story2

        0.000378

        0.000109

        0.000094

        0.000111

        0.000085

        Story3

        0.000418

        0.000128

        0.000042

        0.00011

        0.000107

        Story4

        0.000435

        0.000146

        0.00002

        0.00013

        0.000128

        Story5

        0.000443

        0.00016

        0.000054

        0.000146

        0.000144

        Story6

        0.000449

        0.00017

        0.000082

        0.000158

        0.000157

        Table :9 Story drift along X direction.

        Table :10 Story drift along Y direction

        Story

        Bare building

        Diagonal bracing

        V

        bracing

        Inverted V

        bracing

        X

        bracing

        Base

        0

        0

        0

        0

        0

        Story1

        0.000309

        0.000105

        0.000148

        0.000028

        0.000108

        Story2

        0.000525

        0.00017

        0.000218

        0.000085

        0.000193

        Story3

        0.000587

        0.000215

        0.000255

        0.000143

        0.000221

        Story4

        0.000614

        0.000254

        0.000287

        0.000195

        0.000259

        Story5

        0.00063

        0.000285

        0.000312

        0.000236

        0.000288

        Story6

        0.000642

        0.00031

        0.00033

        0.000269

        0.000309

        Story7

        0.00065

        0.000329

        0.000343

        0.000296

        0.000324

        Story8

        0.000654

        0.000343

        0.00035

        0.000317

        0.000332

        Story9

        0.000648

        0.000351

        0.000353

        0.000332

        0.000334

        Story10

        0.000612

        0.000354

        0.00035

        0.00034

        0.00033

        Story11

        0.000476

        0.000322

        0.00032

        0.000314

        0.000308

        Story12

        0.000235

        0.000237

        0.000227

        0.000215

        0.000232

        Fig :16 shows the story drift due to wind load along Y direction.

        According to above graph, bare building shows maximum drift compare to different braced building in Y direction. Diagonal Bracing shows 45.87% lesser drift, V Bracing shows 46.48% lesser drift, Inverted V Bracing shows 48.08% lesser drift and X Bracing shows 49% lesser drift when compared to the bare building.

      2. Base shear for wind load:

        Bracings

        Fz

        Mx

        My

        without

        56974.17

        290659.6

        -492620

        Diagonal

        58215.8

        296867.7

        -503174

        V Bracing

        58764.88

        299613.1

        -507841

        Inverted V

        58764.88

        303351.6

        -507841

        X bracing

        59457.43

        306814.4

        -513728

        Table :11 Table show base shear due to wind load.

        Fig:17 shows the base shear due to wind load in X direction.

        The Base shear of the bare building is minimum when compared with braced building. Among the all types of bracing X Bracing shows maximum Base shear.

      3. Base shear due to wind load in Y direction.

        Bracings

        Fz

        Mx

        My

        without

        56974.17

        294745.7

        -492620

        Diagonal

        58215.8

        300953.9

        -503174

        V Bracing

        58764.88

        303699.3

        -507841

        Inverted V

        58764.88

        303699.3

        -507841

        X bracing

        59457.43

        307162.1

        -513728

        Table : 12 Base shear due to wind load in Y direction.

  2. CONCLUSION

From this study, analyzed the variation of the lateral displacement, story drift and base shear along X and Y directions. This present study is concluded with the following conclusions.

      • In ESM for the load combinations 1.5(DL+LL+EQX) and 1.5(DL+LL+EQY). The variation of the lateral displacement of the building is compared with the bare building along X and Y direction. The displacement is minimum in X Braced building and maximum in bare building.

      • The ESM for the load combinations 1.5(DL+LL+WX) and 1.5(DL+LL+WY). The variation of lateral displacement of the building is compared with the bare building along X and Y direction. The displacement is minimum in X braced building and maximum in bare building.

      • The ESM for the load combinations 1.5(DL+LL+EQX) and 1.5(DL+LL+EQY). The variation of the story drift of bare building is compared with different types braced building along X and Y direction. The story drift is maximum in bare building and minimum in X braced building.

      • The ESM for the load combinations 1.5(DL+LL+WX) and 1.5(DL+LL+WY). The variation of the story drift of bare building is compared with different types of braced building along X and Y direction. The story drift is maximum in bare building and minimum in X braced building.

      • The ESM for the load combinations 1.5(DL+LL+EQX) and 1.5(DL+LL+EQY). The variation of the base shear of the bare building is compared with the different types of the braced building along X and Y direction. The base shear is minimum in bare building and maximum in X braced building.

      • The ESm for the load combinations 1.5(DL+LL+WX) and 1.5(DL+LL+WY). The variation of the base shear of the bare building is compared with the different types of the braced building along X and Y direction. The base shear is minimum in bare building and maximum in X braced building.

      • From the overall result the displacement and story drift is minimum in braced building and base shear is maximum in Braced building compare to bare building.

Fig :18 Shows the base shear due to Wind load in Y direction.

The Base shear of the bare building is minimum when compared with braced building. Among the all types of bracing X Bracing shows maximum Base shear.

REFERECES

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