High Rise Long Span Steel Structure with Semi-Rigid Connection using Bracing System

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High Rise Long Span Steel Structure with Semi-Rigid Connection using Bracing System

Harsh Rana1, Dr. Darshana R. Bhatt2, Dr. Snehal V. Mevada3 Post Graduate Student1, Associate Professor2, Assistant Professor3 Department of Structural Engineering

Birla Vishvakarma Mahavidyalaya (BVM) Engineering College, Gujarat, India.

Abstract: Generally, in steel structure the connection between beam and column are designed as moment connection and pinned connection, but in actual condition the structure behaves between these two conditions, resulted into semi-rigid condition which is intermediate stage between rigid and pinned joints. Effect of semi-rigid connection on multi-story multi-bay frame is accomplished in this paper. The present study introduces the effect of static and dynamic loading on high rise steel structure of G+15 story with 4m, 6m and 8m three bay span length. Structure is analyzed under two different condition of partial release of semi-rigid connections which is derived by fixity factor of values 0.5 and 0.75 (as per AISC) in this study. The analysis is done commercially available software-STAAD.Pro. From the non-linear analysis, the story displacement and story drift are obtained. The overall performance of the structure from the analysis, semi-rigid joints display more story displacement and story drift compared to rigid joints. To overcome the results, bracing system is introduced at different location of periphery of structure. These brace frame structure consist of X- bracing and diagonal bracing. Again, comparative analysis is to be performed in STAAD.Pro on these three-bay span lengths. It is found that braced semi-rigid frame structure perform quite well as compared to unbraced frame structure.

Keywords: Multi-story Multi-bay frame, Semi-rigid connections, Fixity factor, Brace frame.

  1. INTRODUCTION

    Steel structures are made up of different elements like beams, columns, bracings, flooring and roofing systems. In every structure Beam-to-column connections are important and inherent component of steel frame structure and their behavior influence the global performance of the structure under various loadings. Generally, connections are characterized in two types 1. Moment Connections and 2. Pinned connections. Besides that in actual practice steel connections are not providing ideal rigid or pinned but behavior of connections fall between these two-condition called as semi-rigid connections which basically based on their stiffness criteria. Basically, Connections are classified by their strength as well as their ductility, where ductility is a description of the rotation capacity i.e. rotational stiffness. As per AISC (American institute of Steel construction) fixity factor is derived to evaluate rotational stiffness of member of the structure which is conventional practice but it gives approximate value of partial releases in the structure as well as their behaviour is also influenced on the rotational stiffness of the member

  2. LITERATURE REVIEW

    Nandeesha and Kashinath (2017) Investigated the analysis of multi storey steel space frame by varying fixity factor and found the capacity of strength of joints and to perform linear static of semi-rigid connection steel frame using response spectrum method. Considering 0 fixity f actor for pinned or hinged joints and 1 for rigid joints and the variation of bending moment, shear Force with varying fixity factor was found out. Nihan dogramac aksoylar, Hussam mahmoud (2011) have studied the moment resisting frame with semi- rigid connections and prepared 26 sample model frames were evaluated with pushover and dynamic analysis under

    25 strong ground motion records. Main outcome of investigation was overall top story displacement of structure with semi-rigid structure are smaller than rigid frame structure. Peng deng, yigjuan, Xiaotong shang (2015) had studied comparison of eccentric inclined braced steel frame with semi-rigid connection and simple steel frame with semi-rigid connections. Based on seismic performance the energy dissipation capacity was found out in terms of lateral stability and stiffness of the structure. Mohammad razavi, Ali abolmmali (2014), came up with new concept of hybrid steel frame system, as it contains the mixture of full rigid and semi-rigid steel connections used in 20-storey steel structure. They assigned the semi-rigid connections as replacement of rigid connections at different location of structure. By performing the parametric study of seismic analysis, they corelate the cyclic behaviour of HYBRID frame structure in terms of storey drift and life safety. Anuraj e, Hemalatha g (2018), their effort was made to find out actual behaviour of rigid and semi rigid connection by performing nonlinear static analysis on G+5 storey structure in SAP2000. From analysis, storey drift value and performance points were obtained

  3. METHOLOGY FOR ANALYSIS

    There are many methods to find out capacity of semi-rigid connections, but in this paper needs to estimate rotational stiffness of member of structure. Main aim to analyse the performance of high rise (G+15 storey) long span steel structure with semi-rigid connections using bracing system. It is proposed to carry out the analysis of multi-story multi- bay frame (contains 4m,6m & 8m bay length) considering the ideal rigid and semi-rigid conditions using STAAD.Pro and evaluate the effect of height, span, fixity factor,

    rotational stiffness. Apart from this analysis, in this research widely investigated the comparative analysis of semi-rigid connection with

    Study of various Parameters in Semi- Rigid connections

    or without bracing system. As per convenience, X- Bracing and Diagonal bracing are used at different location of periphery of structure.

    The primary aim of this study to compare the two types of partial release condition as per fixity factor equation.

    Fixity factor considered 0for ideally pinned conditions and 1 fixity for rigid conditions in the analysis of frame. As per past experiences and researches the most favourable results

    are obtained for the range of 0.5 to 0.7 fixity factor.

    Present study incorporates the analysis of steel frame structure using fixity factors 0.5 and 0.75 (i.e. 50% partial release structure and 25% partial release in structure). In end fixity factor, ri is written as

    With bracing

    Analysis and design of long span high rise steel framed structure with semi rigid connection

    Without bracing

    Under static, seismic non-linear loading

    Under static, seismic non-linear loading

    Ri: Rotational Spring Stiffness of connections

    EI/L: Flexural Stiffness of elements

    Using above equation, there are 63 models prepared as per different conditions of fixity factor (0.5 and 0.75), bay lengths and bracing system. The flow chart of methodology of analysis and classification of models are mentioned below.

    Connections

    Rigid Semi-rigid

    Flow chart 1: Scope of study

  4. ANALYSIS

    All primary data are mentioned in table-1 & 2. Apart from this, section properties and loading conditions are given in table- 3 & 4.

    Structural Data

    Building type

    Symmetrical High-rise G+15 storey

    Numbers of bay

    3 In both direction

    Bay length

    4m, 6m and 8m

    Height of building

    48m

    Building type

    /td>

    Symmetrical High-rise G+15 storey

    Numbers of bay

    3 In both direction

    Bay length

    4m, 6m and 8m

    Height of building

    48m

    Table 1: Primary structural data

    As per Different bay length 4m, 6m & 8m and also Different bracing system Total No.

    Middle

    Without bracings

    Corner

    With bracings

    Fixity Factor

    Rotational Stiffness (kN.m/rad)

    ISWB 250

    ISWB300

    ISMB300

    ISMB400

    0.5

    9360.4

    12375.22

    13550.67

    25777.6

    0.75

    26754.9

    39188.18

    42910.465

    81629.02

    Fixity Factor

    Rotational Stiffness (kN.m/rad)

    ISWB 250

    ISWB300

    ISMB300

    ISMB400

    0.5

    9360.4

    12375.22

    13550.67

    25777.6

    0.75

    26754.9

    39188.18

    42910.465

    81629.02

    Table 2; Rotational stiffness of members

    of Models- 63

    z

    Full perimeter

    Section

    Area (m2)

    Modulus of elasticity (E) (kN/m2)

    Moment of inertia (I) m4

    ISWB 250 X

    40.9

    0.005205

    210000000

    0.000059431

    ISWB 300 X

    48.1

    0.006133

    210000000

    0.000098216

    ISMB 300 X

    44.2

    0.005626

    210000000

    0.000086036

    ISMB 400 X

    61.6

    0.007846

    210000000

    0.000204584

    Section

    Area (m2)

    Modulus of elasticity (E) (kN/m2)

    Moment of inertia (I) m4

    ISWB 250 X

    40.9

    0.005205

    210000000

    0.000059431

    ISWB 300 X

    48.1

    0.006133

    210000000

    0.000098216

    ISMB 300 X

    44.2

    0.005626

    210000000

    0.000086036

    ISMB 400 X

    61.6

    0.007846

    210000000

    0.000204584

    Table 3 : Section properties of beams

    Dead load + Live load

    4 kN/m2

    Beam section (UDL) (For all structures)

    ISWB250 ISWB300 ISMB300 ISMB400

    0.409 kN/m

    0.481 kN/m

    0.442 kN/m 0.615 kN/m

    Column Section

    IW500400X012 IW500400X2040 I160016A50040

    Bracings

    (For all structures)

    ISA 150X150X16

    Dead load + Live load

    4 kN/m2

    Beam section (UDL) (For all structures)

    ISWB250 ISWB300 ISMB300 ISMB400

    0.409 kN/m

    0.481 kN/m

    0.442 kN/m 0.615 kN/m

    Column Section

    IW500400X012 IW500400X2040 I160016A50040

    Bracings

    (For all structures)

    ISA 150X150X16

    Table 4 : Loadings and primary data of columns and bracing

    In STAAD.Pro, the partial releases are providing at start and end of the beam members which is mentioned below fig-1.

    Figure 1: Using Partial Release in Beam Section for semi rigidity

    Mainly two type of bracing system (X and diagonal) are provided on different location of periphery of structure. The detailed rendering view of structures are presented in fig-2 & 3.

    Figure 2: Different locations of provision of X – Bracings

    Figure 3: Different locations of provision of diagonal Bracings

  5. PARAMETERS FOR EARTHQUAKE AND

    WIND ANALYSIS

    Table 4: Seismic analysis data

    AS PER IS 1893 2016 PART I

    USING RESPONSE SPECRTRUM ANALYSIS

    City

    Ahmedabad

    Zone

    III 0.16

    Response Reduction Factor(R)

    5 (Steel Structure with SMRF frame)

    Importance Factor(I)

    1

    Combination Method

    CQC method

    Soil Type

    Medium Soil

    Damping Ratio

    0.05

    (Sa/g)*(Z/R)

    0.016 (X and Z direction)

    Time

    5.94 s

    Acceleration

    3.33426 m/s2

    Table 5: Wind analysis data

    AS PER IS 875 PART- III 2015

    Design Wind speed

    Vz = Vb*K1*K2*K3 Where Vb = 39 m/s

    Height (m)

    Wind pressure(kN/m2) pz = 0.6*Vz2

    10

    0.732

    15

    0.796

    20

    0.859

    30

    0.930

    48

    1.133

    After providing bracing (X and diagonal), reduction in lateral displacement as per bay lengths are shown in fig-6 to fig-11.

  6. RESULTS

    From the parametric analysis results (in mm) are in terms of lateral displacement and lateral drift (Both permissible

    <=L/300) as characterized in three different (4m, 6m & 8m) bay length nd fixity factors are mentioned below.

    1. For 50% release i.e fixity factor is 0.5

    2. For 25% release i.e fixity factor is 0.75

    Also, measure the effect of bracing system (X and Diagonal Bracing) on lateral stability of structure.

    200

    150

    200

    150

    The results comparison of lateral displacement between rigid connection and semi-rigid connection for three bay lengths are shown in fig- 4 and 5.

    250

    250

    238

    238

    Displacement for Bay length 4m

    Displacement for Bay length 4m

    80

    70

    60

    50

    40

    30

    20

    10

    0

    71

    61

    80

    70

    60

    50

    40

    30

    20

    10

    0

    71

    61

    0.5 0.75

    Full perimeter Middle Corner

    0.5 0.75

    Full perimeter Middle Corner

    28

    28

    31

    31

    22

    22

    21

    21

    Figure 6: X-bracing

    170

    170

    400

    350

    300

    250

    200

    150

    100

    50

    0

    100

    100

    97

    97

    50

    0

    50

    0

    Displacement

    4m 6m 8m

    Displacement

    4m 6m 8m

    Figure 4: Rigid Connections

    Displacement

    335

    288

    335

    288

    308

    220

    160

    122

    4m 6m 8m

    140

    120

    100

    80

    60

    40

    20

    0

    Displacement for bay length 4m

    117

    100

    72

    75

    63

    65

    0.5 0.75

    Full perimeter Corner Middle

    Figure 7: Diagonal bracing

    0.5 0.75

    Figure 5: Semi-Rigid Connections

    Displacement for bay length 6m

    Displacement for bay length 6m

    Displacement for bay length 6m

    Displacement for bay length 6m

    32

    32

    120

    100

    120

    100

    99

    99

    80

    80

    91

    91

    60

    60

    59

    59

    40

    40

    56

    56

    20

    20

    31

    31

    0

    0

    0.5

    0.5

    0.75

    0.75

    Full perimeter Corner Middle

    Full perimeter Corner Middle

    91

    91

    160

    140

    120

    100

    80

    60

    40

    20

    0

    160

    140

    120

    100

    80

    60

    40

    20

    0

    137

    137

    118

    118

    97

    97

    103

    103

    94

    94

    0.5 0.75

    Full perimeter Corner Middle

    0.5 0.75

    Full perimeter Corner Middle

    Figure 8: X-bracing

    Displacement for bay lengh 8m

    Displacement for bay lengh 8m

    140

    120

    100

    80

    117

    110

    140

    120

    100

    80

    117

    110

    60

    40

    20

    0

    68

    64

    60

    40

    20

    0

    68

    64

    0.5 0.75

    Full perimeter Corner Middle

    0.5 0.75

    Full perimeter Corner Middle

    44

    44

    43.9

    43.9

    Figure 10: X-bracing

    Figure 9: Diagonal bracing

    Displacement for bay length 8m

    Displacement for bay length 8m

    180

    160

    140

    120

    100

    80

    60

    40

    20

    0

    162

    180

    160

    140

    120

    100

    80

    60

    40

    20

    0

    162

    0.5 0.75

    Full perimeter Corner Middle

    0.5 0.75

    Full perimeter Corner Middle

    135

    135

    150

    150

    110

    110

    98

    98

    93

    93

    Figure 11: Diagonal bracing

    25

    20

    15

    10

    25

    20

    15

    10

    80

    70

    60

    80

    70

    60

    75

    75

    50

    40

    30

    20

    50

    40

    30

    20

    55

    55

    Same as the comparison of results of lateral drift between rigid connection and semi-rigid connection for three bay lengths are shown in fig-12 and 13.

    Drift

    Drift

    Drift

    Drift

    35

    30

    33.3

    35

    30

    33.3

    0

    4m

    6m

    8m

    0

    4m

    6m

    8m

    4m 6m 8m

    0.5 0.75

    4m 6m 8m

    0.5 0.75

    10.8

    10.8

    5

    5

    6.4

    6.4

    28

    28

    10

    0

    10

    0

    21

    21

    16

    16

    11

    11

    Figure 12: Rigid Connections Figure 13: Semi-Rigid Connections

    As per different bay lengths and bracing system comparison of lateral drift are as shown in fig- 14 to 19.

    Drift for bay length 4m

    Drift for bay length 4m

    Drift for bay length 4m

    9

    8

    7

    6

    5

    4

    3

    2

    1

    0

    9

    8

    7

    6

    5

    4

    3

    2

    1

    0

    6

    7.63

    7.63

    5.12

    4.93

    3.97

    2.9

    1.58

    1.27

    5.12

    4.93

    3.97

    2.9

    1.58

    1.27

    5

    5.32

    5.32

    4

    6

    5.98

    6

    5.98

    4.86

    4.86

    3

    3.96

    3.96

    2

    1

    0

    0.5 0.75

    Full perimeter Corner Middle

    0.5 0.75

    Full perimeter Corner Middle

    0.5 0.75

    Full perimeter Corner Middle

    Figure 14: X-bracing Figure 15: Diagonal bracing

    Drift for bay length 6m Drift for bay length 6m

    9

    8

    7

    6

    5

    4

    3

    2

    1 1.9

    0

    4.15

    3.8

    10

    9

    8

    7

    6.31

    6.31

    6 7.15

    5

    4

    3

    2

    1

    0

    4.67

    4.67

    5.98

    1.36

    1.36

    7.63

    7.63

    6.5

    6.5

    8.58

    8.58

    7.32

    7.32

    0.5 0.75 0.5 0.75

    Full perimeter Corner Middle Full perimeter Corner Middle

    Figure 16: X-bracing Figure 17: Diagonal bracing

    Drift for bay length 8m

    Drift for bay length 8m

    Drift for bay length 8m

    14

    12

    10

    8

    6

    4

    2

    0

    14

    12

    10

    8

    6

    4

    2

    0

    9

    7.9

    6.88

    5.91

    4.83

    2.56

    2.03

    7.9

    6.88

    5.91

    4.83

    2.56

    2.03

    8

    12.19

    12.19

    7

    6

    9.15

    9.15

    8.25

    8.25

    5

    7.19

    7.19

    7.02

    7.02

    4

    5.55

    5.55

    3

    2

    1

    0

    0.5 0.75

    Full perimeter Corner Middle

    0.5 0.75

    Full perimeter Corner Middle

    0.5 0.75

    Full perimeter Corner Middle

    Figure 18: X-bracing Figure 19: Diagonal bracing

  7. CONCLUSION

    • From the overall analysis, it has been observed that lateral displacement in semi-rigid connection is more than rigid connections as well as increasing in bay length.

    • Reduction in results with increasing the flexibility of connection about fixity factor 0.75 as compare to fixity factor 0.5.

    • As span increase the more lateral displacement observed. To overcome this effect the bracing system is used to improve the lateral stability of structure. The analysis results of X-braced frame have indicated more lateral stability than diagonal braced frame.

    • In the overall seismic analysis of high-rise structure, corner and full perimeter braced frame enhance to give least lateral displacement and drift comparing with middle braced frame from above figures.

  8. REFERENCES

  1. Nandee-sha G. , Kashinath B. Rugi, Nov-2017, Influence of semi-rigid connection on behavior of steel frame under static loads, International Research journal of engineering and technology (IRJET), vol. 4, pp. 1441-1445.

  2. Arunraj e and hemalatha G, Nctober 2018, Performance analysis of semi rigid connection over rigid and hinged connections, International journal of civil engineering and technology (IJCIET) vol-9, pp.1749-1755.

  3. Mohammad Razavi, Ali Abolmaali, 22 February 2014, Earthquake resistance frames with combination of rigid and semi-rigid connections, Journal of Constructional Steel Research, vol-98, pp. 1-11.

  4. Nihan Dogramac Aksoylar , Amr S. Elnashai , Hussam Mahmoud , 9 July 2010, The design and seismic performance of low-rise long-span frames with semi-rigid connections, Journal of Constructional Steel Research, vol-67, pp. 114- 126.

  5. Peng Deng, Yingjuan Ma ,Xiaotong Shang, Research on Seismic Behavior of Semi-rigid Steel Frame Structures With Eccentric Brace, 5th International Conference on Advanced Engineering Materials and Technology (AEMT 2015).

  6. Sanjaykumar N. Sonune, Dr. Nagesh L. Shelke, 2017, Response of structural steel frame by using semi-rigid connections, International journal of advance research and innovative ideas in education, vol-3, pp. 1675-1686.

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