Comparative Study of Story Displacement and Stiffness under Different Seismic Zones for RC Structure

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  • Open Access
  • Authors : Sagar Laxman Belgaonkar , Ravi Basavaraj Tilaganji , Priyanka P Hegade, Raghavi B Indaragi , Karishma Z Jamadar, Naveen N Biradar
  • Paper ID : IJERTV10IS070230
  • Volume & Issue : Volume 10, Issue 07 (July 2021)
  • Published (First Online): 27-07-2021
  • ISSN (Online) : 2278-0181
  • Publisher Name : IJERT
  • License: Creative Commons License This work is licensed under a Creative Commons Attribution 4.0 International License

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Comparative Study of Story Displacement and Stiffness under Different Seismic Zones for RC Structure

Prof. Sagar Laxman Belgaonkar1

1Assistant Professor, Department of Civil Engineering Angadi Institute of Technology and Management Belagavi, Karnataka, India

Prof. Ravi Basavaraj Tilaganji2

2Assistant Professor, Department of Civil Engineering Angadi Institute of Technology and Management Belagavi, Karnataka, India

Miss. Priyanka P Hegade3, Miss. Raghavi B Indaragi4, Miss. Karishma Z Jamadar5, Mr. Naveen N Biradar6.

3,4,5,6 Undergraduate students, Civil Engineering Department, AITM, Belagavi 590009

Abstract Structural developments are increasing rapidly now-a-days throughout the world. Natural calamities like earthquake are happening frequently around the world, hence, the structure has to be designed for the same. The critical seismic analysis of reinforced concrete building, specifically involves the understanding behavior of structure under lateral loads unlike the usual gravity loads such as dead loads and the live loads.

In order to design an earthquake resistant structure, the analysis of the structure G+9 story is done using ETABS 2013. G + 9 story is analyzed for different types of seismic zones and soil types as per IS 1893:2016. Further the behavior of the structure is studied for the parameters such as Natural period, Displacement, Base shear and Story Stiffness.

Keywords Seismic Zoning, Soil Types, Natural Period, Displacement, Base Shear, Story Stiffness.

  1. INTRODUCTION

    Natural calamities like earthquakes are the most dangerous by means of the damage to the structural components and they cannot be predicted and controlled due to sudden occurrence. But attempt can be made to minimize the vulnerable seismic effects. Seismic waves travel through earths layers as a result shaking of earth surface leads to damage of structure. Also, these lateral loads can develop high stress, produce sway movements or cause vibration. Therefore, it is very important for the structure to have sufficient strength with adequate stiffness to resist lateral forces. The existing buildings are vulnerable to earthquake, so the importance has been given for earthquake resistant of building.

    The analysis of structure for the seismic resistance involves the understanding the behavior of the structure under lateral loads and normal loads. In this study structural analysis of building based on the seismic zones of the area and the types of soils is carried out. The seismic zones are II, III, IV and V among these, zone V is the high active region and zone II is the low active region in India. The behavior of structure under various seismic zones and soil types has been studied.

  2. METHODOLOGY

    1. Details of Structure and Analysis

      The analysis of G+9 RC Structure is carried out. Seismic analysis according to IS 1893 (Part-1):2016. Analysis is carried out for structure in zone II, III IV and V.

      Effects of Earthquake loads applied on the structures are studied in two methods, namely

      1. Equivalent static method

      2. Dynamic analysis method

    2. Modelling

      The model is analyzed in ETABS 2013 by the following steps

      1. Material properties such as grade of concrete, grade of steel is defined.

      2. Section Properties are assigned as (beam, column, slab).

      3. The columns are restrained at base level.

      4. The loads are applied onto the structural members.

      5. Different load cases and combinations are carried out.

      6. Function is assigned based on seismic parameters considered for analysis of structure.

      TABLE 1: MODELS CONSIDERED FOR ANALYSIS

      Model number

      Description of Models

      Model 1

      Building with seismic details of Zone-II and Soil type-1

      Model 2

      Building with seismic details of Zone-II and Soil type-2

      Model 3

      Building with seismic details of Zone-II and Soil type-3

      Model 4

      Building with seismic details of Zone-III and Soil type-1

      Model 5

      Building with seismic details of Zone-III and Soil type-2

      Model 6

      Building with seismic details of Zone-III and Soil type-3

      Model 7

      Building with seismic details of Zone-IV and Soil type-1

      Model 8

      Building with seismic details of Zone-IV and Soil type-2

      Model 9

      Building with seismic details of Zone-IV and Soil type-3

      Model 10

      Building with seismic details of Zone-V and Soil type-1

      Model 11

      Building with seismic details of Zone-V and Soil type-2

      Model 12

      Building with seismic details of Zone-V and Soil type-3

    3. Structural Properties

      TABLE 2: PROPERTIES OF STRUCTURE

      Description

      Dimension/Properties

      Building Dimension

      30m × 40m

      Height of each Story

      3m

      Column Size

      450mm × 600mm (1st 5th Story) 300mm × 450mm (6th 10th Story) 200mm × 300mm (All Story)

      Beam Size

      300mm × 450mm (1st 5th Story) 250mm × 300mm (6th 10th Story)

      Wall Thickness

      300mm (Periphery wall) 230mm (Partition wall)

      Slab Thickness

      130mm (1st 5th Story) 120mm (6th 10th Story) 100mm (Parking area)

      TABLE 3: PROPERTIES OF CONCRETE

      Description

      Properties

      Concrete Grade

      M25

      Elastic Modulus

      25000 MPa

      Poissons Ratio

      0.2

      Density of Concrete

      25 kN/m3

      TABLE 4: PROPERTIES OF STEEL

      Description

      Properties

      Grade of Steel

      Fe500

      Elastic Modulus

      200000 MPa

      Poissons Ratio

      0.3

    4. Seismic Details

    TABLE 5: SEISMIC PROPERTIES ACCORDING TO IS 1893 (PART-1)

    : 2016

    Description

    Properties

    Soil Type

    Type-1-Rock or Hard Soil (Model-1, 4, 7 & 10)

    Type-2-Medium Soil (Model-2, 5, 8 & 11)

    Type-3-Soft Soil (Model-3, 6, 9 & 12)

    Importance factor (I)

    1.5

    Reduction factor (R)

    5

    Zone factor (Z)

    Zone-II 0.10 (1st _ 3rd Model) Zone-III 0.16 (4th _ 6th Model) Zone-IV 0.24 (7th _ 9th Model) Zone-V 0.36 (10th _ 12th Model)

  3. PLAN AND ELEVATION

    Fig.1Plan of the Structure

    Fig.2 Elevation of the Structure

  4. RESULTS AND DISCUSSION

The models are analyzed for Equivalent Static Force Method results of the models for different seismic zones and soil types are discussed below

  1. Natural Period for all the Models

    TABLE 6: COMPARTIVE ESULTS FOR NATURAL PERIOD

    Model

    Natural Period (secs)

    1

    2.722

    2

    2.710

    3

    2.623

    4

    2.601

    5

    2.518

    6

    2.515

    7

    3.001

    8

    3.295

    9

    3.593

    10

    3.690

    11

    3.786

    12

    3.795

    3.9

    3.8 Comparison of Natural Period

    3.7

    3.6

    Natural Period in Secs

    Natural Period in Secs

    3.5

    3.4

    3.3

    3.2

    3.1

    3.0

    2.9

    2.8

    2.7

    2.6

    2.5

    2.4

    From the Graph 2, it is observed that Model 3 has the highest displacement which is 1.67 times higher than the Model 1 and 0.81 times higher than Model 2. This is due to the Model 3 is present in Soft Soil.

    TABLE 8: COMPARTIVE RESULTS FOR DISPLACEMENT FOR THE MODELS IN SEISMIC ZONE III

    Results for Displacements (mm) Zone-III

    Story

    Model 4

    Model 5

    Model 6

    10

    31.5

    42.9

    42.9

    9

    29.3

    39.8

    39.8

    8

    25.8

    35.1

    35.1

    7

    21.8

    28.9

    28.9

    6

    16.1

    22

    22

    5

    11.6

    15.7

    15.7

    4

    8.7

    11.8

    11.8

    3

    5.9

    8

    7.4

    2

    3.2

    4.3

    4.3

    1

    1.1

    1.4

    1.4

    Results for Displacements (mm) Zone-III

    Story

    Model 4

    Model 5

    Model 6

    10

    31.5

    42.9

    42.9

    9

    29.3

    39.8

    39.8

    8

    25.8

    35.1

    35.1

    7

    21.8

    28.9

    28.9

    6

    16.1

    22

    22

    5

    11.6

    15.7

    15.7

    4

    8.7

    11.8

    11.8

    3

    5.9

    8

    7.4

    2

    3.2

    4.3

    4.3

    1

    1.1

    1.4

    1.4

    0 1 2 3 4 5 6 7 8 9 10 11 12 13

    Model

    GRAPH 1: COMPARISON OF NATURAL PERIOD (SECS)

    1. The natural period for Model 6 is the least with comparing to other models.

    2. The natural period for Models 11 & 12 are the highest with comparing to other models, as they are under seismic zone V. They are almost 1.5 times greater than the least model value.

    3. From the Graph 1, it is observed that Model 4, 5 & 6 shows the least affected by the seismic forces. (which lies in seismic zone III)

  2. Displacements for all the Models

    The displacement comparison is done on the basis of different seismic zones

    TABLE 7: COMPARTIVE RESULTS FOR DISPLACEMENT FOR THE MODELS IN SEISMIC ZONE II

    Model4

    Model4

    Model5

    Model5

    Model6

    Model6

    45

    40

    35

    Displacement(mm)

    Displacement(mm)

    30

    25

    20

    15

    10

    5

    0

    0 1 2 3 4 5 6 7 8 9 10 11

    Story

    Model1 Model2 Model3

    Model1 Model2 Model3

    Resu

    lts for Displace

    ments (mm) Z

    one-II

    Story

    Model 1

    Model 2

    Model 3

    10

    19.7

    26.8

    32.9

    9

    18.3

    24.9

    30.6

    8

    16.1

    21.9

    26.9

    7

    13.3

    18.1

    22.2

    6

    10.1

    13.7

    16.8

    5

    7.2

    9.8

    12.1

    4

    5.4

    7.4

    9

    3

    3.4

    4.6

    6.1

    2

    2

    2.7

    3.3

    1

    0.5

    0.9

    1.1

    Resu

    lts for Displace

    ments (mm) Z

    one-II

    Story

    Model 1

    Model 2

    Model 3

    10

    19.7

    26.8

    32.9

    9

    18.3

    24.9

    30.6

    8

    16.1

    21.9

    26.9

    7

    13.3

    18.1

    22.2

    6

    10.1

    13.7

    16.8

    5

    7.2

    9.8

    12.1

    4

    5.4

    7.4

    9

    3

    3.4

    4.6

    6.1

    2

    2

    2.7

    3.3

    1

    0.5

    0.9

    1.1

    35

    30

    Displacement (mm)

    Displacement (mm)

    25

    20

    15

    10

    5

    0

    0 1 2 3 4 5 6 7 8 9 10 11

    Storey

    GRAPH 3: COMPARISON OF DISPLACEMENTS FOR MODELS IN SEISMIC ZONE III

    From the Graph 3, it is observed that Model 5 & 6 has the highest displacement and almost same and both are 1.36 times higher than the Model 4. The displacement is less in Model 4 as it lies in Hard Soil.

    TABLE 9: COMPARTIVE RESULTS FOR DISPLACEMENT FOR THE MODELS IN SEISMIC ZONE IV

    td>

    2.3

    Results for Displacements (mm) Zone-IV

    Story

    Model 7

    Model 8

    Model 9

    10

    68

    92.7

    113.6

    9

    62.3

    84.1

    104

    8

    54.9

    74.7

    91.7

    7

    46

    62.6

    76.8

    6

    36.3

    49.4

    60.7

    5

    27.4

    37.3

    45.8

    4

    20.2

    27.5

    33.7

    3

    13.5

    18.3

    22.5

    2

    7.2

    9.8

    12.1

    1

    3.1

    3.9

    GRAPH 2: COMPARISON OF DISPLACEMENTS FOR MODELS IN SEISMIC ZONE II

    120

    110

    100

    90

    Displacement(mm)

    Displacement(mm)

    80

    70

    60

    50

    40

    30

    20

    10

    0

    Model7 Model8 Model9

    0 1 2 3 4 5 6 7 8 9 10 11

    story

    From the Graph 5, it is observed that Model 12 has the highest displacement which is 1.67 times higher than the Model 10 and 1.23 times higher than Model 11. This is due to the Model 12 is present in Soft Soil.

    Referring to the Graph 2, 4 and 5, the behavior of structure is similar in soil types I, II and III. The soil type III shows the higher displacement of the structure.

    Referring to Graph 3, the behavior of the structure is similar in soil types II and III. The soil type I shows the least displacement of the structure.

  3. Stiffness of all the Models

    The Stiffness comparison is done on the basis of different seismic zones

    Results for Stiffness (kN/m) Zone-II

    Story

    Model 1

    Model 2

    Model 3

    10

    28584

    27743.05

    28157.253

    9

    38689.75

    38040.265

    38363.263

    8

    42382.83

    41863.195

    48121.41

    7

    45986.967

    45571.64

    45778.361

    6

    56932.417

    56296.551

    56612.699

    5

    85667.99

    83258.342

    84444.438

    4

    94325.538

    91903.338

    93098.686

    3

    103994.431

    101519.964

    1O2742.301

    2

    132794.71

    129703.08

    131230.69

    1

    275937.313

    269338.355

    272597.903

    Results for Stiffness (kN/m) Zone-II

    Story

    Model 1

    Model 2

    Model 3

    10

    28584

    27743.05

    28157.253

    9

    38689.75

    38040.265

    38363.263

    8

    42382.83

    41863.195

    48121.41

    7

    45986.967

    45571.64

    45778.361

    6

    56932.417

    56296.551

    56612.699

    5

    85667.99

    83258.342

    84444.438

    4

    94325.538

    91903.338

    93098.686

    3

    103994.431

    101519.964

    1O2742.301

    2

    132794.71

    129703.08

    131230.69

    1

    275937.313

    269338.355

    272597.903

    TABLE 11: COMPARTIVE RESULTS FOR STIFFNESS FOR THE MODELS IN SEISMIC ZONE II

    GRAPH 4: COMPARISON OF DISPLACEMENTS FOR MODELS IN SEISMIC ZONE IV

    From the Graph 4, it is observed that Model 9 has the highest displacement which is 1.67 times higher than the Model 7 and 1.22 times higher than Model 8. This is due to the Model 9 is present in Soft Soil.

    TABLE 10: COMPARTIVE RESULTS FOR DISPLACEMENT FOR THE MODELS IN SEISMIC ZONE V

    Result

    s for Displace

    ments (mm) Zo

    ne-V

    Story

    Model 10

    Model 11

    Model 12

    10

    102

    138.2

    170.4

    9

    93.4

    127

    155.9

    8

    82.4

    112

    137.6

    7

    69

    93.9

    115.3

    6

    54.5

    74.1

    91.1

    5

    41.1

    55.9

    68.7

    4

    30.3

    41.2

    50.6

    3

    20.2

    27.4

    33.7

    2

    10.8

    14.8

    18.1

    1

    3.5

    4.7

    5.8

    Model10 Model11 Model12

    Model10 Model11 Model12

    180

    300000

    250000

    Stiffness(KN/m)

    Stiffness(KN/m)

    200000

    150000

    100000

    50000

    0

    Model1

    Model2

    Model3

    Model1

    Model2

    Model3

    0 1 2 3 4 5 6 7 8 9 10 11

    Story

    160

    140

    GRAPH 6: COMPARISON OF STIFFNESS FOR MODELS IN SEISMIC ZONE II

    Displacement(mm)

    Displacement(mm)

    120

    100

    80

    60

    40

    20

    0

    0 1 2 3 4 5 6 7 8 9 10 11

    Story

    From the Graph 6, it is observed that all Models behaves similar.

    Results for Stiffness (kN/m) Zone-III

    Story

    Model 4

    Model 5

    Model 6

    10

    28584.008

    27743.054

    28584.008

    9

    38689.758

    38040.265

    38689.758

    8

    42382.83

    41863.195

    42382.83

    7

    45986.967

    45571.64

    45986.967

    6

    56432.417

    56296.551

    56932.417

    5

    85667.993

    83255.342

    85667.993

    4

    94325.538

    91903.338

    94325.538

    3

    103994.431

    101519.964

    103994.431

    2

    132794.071

    129701.083

    132794.71

    1

    275937.313

    269338.355

    175937.313

    Results for Stiffness (kN/m) Zone-III

    Story

    Model 4

    Model 5

    Model 6

    10

    28584.008

    27743.054

    28584.008

    9

    38689.758

    38040.265

    38689.758

    8

    42382.83

    41863.195

    42382.83

    7

    45986.967

    45571.64

    45986.967

    6

    56432.417

    56296.551

    56932.417

    5

    85667.993

    83255.342

    85667.993

    4

    94325.538

    91903.338

    94325.538

    3

    103994.431

    101519.964

    103994.431

    2

    132794.071

    129701.083

    132794.71

    1

    275937.313

    269338.355

    175937.313

    TABLE 12: COMPARTIVE RSULTS FOR STIFFNESS FOR THE MODELS IN SEISMIC ZONE III

    GRAPH 5: COMPARISON OF DISPLACEMENTS FOR MODELS IN SEISMIC ZONE V

    Model4

    Model5

    Model6

    Model4

    Model5

    Model6

    300000

    250000

    Stiffness(KN/m)

    Stiffness(KN/m)

    200000

    150000

    100000

    TABLE 14: COMPARTIVE RESULTS FOR STIFFNESS FOR THE MODELS IN

    SEISMIC ZONE V

    Results for Stiffness (kN/m) Zone-V

    Story

    Model 10

    Model 11

    Model 12

    10

    27520.538

    25310.835

    27215.675

    9

    36633.837

    33126.378

    36215.632

    8

    41336.805

    40129.058

    41013.313

    7

    40950.586

    39320.193

    40150.130

    6

    54877.788

    52143.189

    53312.635

    5

    83453.006

    81231.216

    82152.165

    4

    92109.921

    90126.319

    91102.219

    3

    101775.054

    100563.132

    101435.013

    2

    12353.308

    10132.231

    12053.156

    1

    265360.425

    232180.025

    252130.269

    Results for Stiffness (kN/m) Zone-V

    Story

    Model 10

    Model 11

    Model 12

    10

    27520.538

    25310.835

    27215.675

    9

    36633.837

    33126.378

    36215.632

    8

    41336.805

    40129.058

    41013.313

    7

    40950.586

    39320.193

    40150.130

    6

    54877.788

    52143.189

    53312.635

    5

    83453.006

    81231.216

    82152.165

    4

    92109.921

    90126.319

    91102.219

    3

    101775.054

    100563.132

    101435.013

    2

    12353.308

    10132.231

    12053.156

    1

    265360.425

    232180.025

    252130.269

    50000

    0

    0 1 2 3 4 5 6 7 8 9 10 11

    Story

    GRAPH 7: COMPARISON OF STIFFNESS FOR MODELS IN SEISMIC ZONE III

    From the Graph 7, it is observed that all Models behaves similar for Story 2 to 10. The variation is observed for the story 1 in the Model 6 having least stiffness.

    Results for Stiffness (kN/m) Zone-IV

    Story

    Model 7

    Model 8

    Model 9

    10

    28520.538

    26310.567

    28121.563

    9

    38633.837

    37030.637

    38334.853

    8

    42336.805

    41736.613

    42136.952

    7

    45950.586

    43570.706

    45751.934

    6

    56877.788

    55405.052

    56572.520

    5

    85453.006

    84423.136

    84451.152

    4

    94109.291

    93167.543

    93091.354

    3

    103775.054

    102775.652

    102631.168

    2

    132523.308

    130523.115

    131030.254

    1

    275360.425

    265330.932

    272350.183

    Results for Stiffness (kN/m) Zone-IV

    Story

    Model 7

    Model 8

    Model 9

    10

    28520.538

    26310.567

    28121.563

    9

    38633.837

    37030.637

    38334.853

    8

    42336.805

    41736.613

    42136.952

    7

    45950.586

    43570.706

    45751.934

    6

    56877.788

    55405.052

    56572.520

    5

    85453.006

    84423.136

    84451.152

    4

    94109.291

    93167.543

    93091.354

    3

    103775.054

    102775.652

    102631.168

    2

    132523.308

    130523.115

    131030.254

    1

    275360.425

    265330.932

    272350.183

    TABLE 13: COMPARTIVE RESULTS FOR STIFFNESS FOR THE MODELS IN SEISMIC ZONE IV

    300000

    250000

    Stiffness(KN/m)

    Stiffness(KN/m)

    200000

    150000

    100000

    50000

    0

    Model7

    Model8 Model9

    0 1 2 3 4 5 6 7 8 9 10 11

    Story

    GRAPH 9: COMPARISON OF STIFFNESS FOR MODELS IN SEISMIC ZONE V

    From the Graph 9, it is observed that all Models behaves similar. In story 2 has least stiffness which could affect the structure

    CONCLUSIONS

    1. From Table 1, it is seen that the natural period is the least for model 6 being in Seismic zone III.

    2. Natural Period is higher for the model 8,9,10,11 & 12 having seismic zone IV and V. They are having almost

      1.5 times more than the models under seismic zone II & III.

    3. From Graph 1 and Table 1, it is observed that the Natural Period is more in case of Models under Soft Soils.

    4. From Graph 2,3,4,5, it is observed that the displacement is having similar behavior in all stories in all models.

    5. From Displacements comparison it is observed that the

      GRAPH 8: COMPARISON OF STIFFNESS FOR MODELS IN SEISMIC ZONE IV

      From the Graph 8, it is observed that all Models behaves similar.

      displacements are higher for models under soft soils.

    6. Displacements are higher on the upper stories, due to the effects of different seismic zones and Soil types.

    7. Displacements for models with soil type III are almost

      1.67 times higher than that of Models with Soil Type I.

    8. From Graph 6,7,8,9 it is observed that the stiffness is higher in lower stories and for the models under soil type I.

    9. From Story stiffness comparison tables, it is observed to have least story stiffness in 2nd story for the models with seismic zone IV & V and Soil Type II.

    10. From the study it is observed that for models with seismic zone II are the least affected with the seismic forces as compared to the other models.

REFERENCES

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  2. Dr. Vinod Hosur, Earthquake Resistant Design of Building Structure, Wiley Publication, March 2017, Pp 126.

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