Wind Analysis of a Industrial Steel Structure with Varying Connections in the Member

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Wind Analysis of a Industrial Steel Structure with Varying Connections in the Member

Prof. Sagar L.Belgaonkar1

Assistant Professor Department of Civil Engineering

  1. G. Balekundri Institute of Technology Belgaum, India

    Prof. Madhuri N Kesarkar2 Assistant Professor Department of Civil Engineering

    Miss. Manisha Balaram Kakatkar3 Post Graduate Student

    Department of Civil Engineering

    S. G. Balekundri Institute of Technology Belgaum, India

    Abstract In this report, type of structure and most feasible type of connection, different types of connections, compare the node displacements and to suggest a suitable type of connection are studied. Analysis is carried out by using STAAD Pro. to see the range of parameters such as node displacement, beam relative displacement, beam end forces, weight and beam forces such as maximum axial forces, bending moments and shear forces of the structure.

    KeywordsBolted; welded; shear and moment connections; wind load; maximum node displacement; bending moment; shear force; weight and axial force.

    1. INTRODUCTION

      Connections are the glue that holds a steel structure together. Connections facilitate flow of moments and different types of forces in members and also allow transfer of forces up to foundation level. The ultimate moto or goals of connection design is to have a economical, safe and not so complex design, so that without any difficulty it can be produced and assembled at site. Connection depends on type of loading, strength, stiffness, economy and difficulty or ease of erection. Connecting materials such as angles, plates etc. are fixed to one member at workshop and other member in the field.

      1. Objectives

        • To study the range of moments and general connection details.

        • To study the type of structure and most feasible type of connection.

        • To study different types of connections.

        • To compare the node displacements and to suggest a suitable type of connection.

    2. CONNECTIONS

      1. Bolted connections

        • Nuts

          Types of nuts

          1. Standard : height is approx. 0.8 d

          2. High : height is 1.2 to 2 d

          3. Low : height is 0.4 d Where, d = diameter of bolt

        • Washers

          Types of washers

            1. Standard washers

            2. Standard but hardened for slip-resistant connections

            3. Wedge washers for connection to flange of I-sections.

          • Bolts

            Type of bolts

            1. Black bolts

            2. Turned bolts

            3. Ribbed bolts

            4. High-Strength bolts

      2. Welded Connections

        Types of welds

        • Fillet weld

        • Groove weld

        • Slot and plug weld

      3. Shear connections

        A connection is required to transfer a force only and there may not be any moment acting on the group of connectors, even though the connection may be capable of transmitting some amount of moment. Such a connection is referred as a shear, simple, pinned, force connection.

        Types of simple connections

        • Lap and butt joints

        • Truss joint connections

        • Connections at beam column junctions

          1. Web angle connection

          2. Seat angle connection

          3. Stiffened seat angle connection

          4. Header plate connections

        • Tension and flange splices

      4. Moment Resistant Connections

        A connection which is capable of transferring moment, axial force and shear from one member to another is referred as moment resistant connection.

        Types of Moment Resistant connections

        • Eccentrically loaded connections

        • T-stub connections

        • Flange angle connections

      Table 2: Description of the types of models

      Sl. no

      Numbers of models

      Model 1

      Model 2

      Model 3

      Model 4

      Model 5

      1

      Plan size

      12m x 12m

      12m x 12m

      40m x 40m

      40m x 40m

      40m x 40m

      2

      Bay size

      6m

      6m

      20m

      20m

      20m

      3

      Height

      3.2m

      3.2m

      3.2m

      3.5m

      3.7m

      4

      Column size

      ISWB 600

      ISWB 600

      ISWB 600

      ISWB 600

      ISWB 600

      5

      Beam size

      ISHB 450

      ISHB 450

      ISHB 450

      ISHB 450

      ISHB 450

      6

      Central beam size

      UB610

      x229x1 39.9

      UB610

      x 229×13

      9.9

      UB610 x229 x139.9

      UB610

      x 229×13

      9.9

      7

      Rectangular concrete plinth beam size

      250m

      mx 600m

      m

      250mm x 600mm

      250mm x 600mm

      250mm x600m m

      250m

      x600m m

    3. Methodology

  1. General

    The present work is carried to study the difference between structural connections and behavior of structure with different types of structural connections. The software used for the analysis is STAAD Pro V8i. A plan of three storey steel structure building is considered as a model, analysis is done using STAAD Pro V8i. and the design of structural joints is carried manually using excel sheets.

    Following studies are carried:

    • Difference between bolted and welded connections

    • Behavior of structure with different structural connections at different location of structure.

    • Different types of structural connections will be checked for wind speed

    • The range of moments and general connection details are studied.

    • The most feasible type of connection for the type of structure is studied

  2. STAAD Pro V8i

    STAAD Pro V8i is a full featured program that can be used for the simplest programs or the most complex projects. This software gives better result of steel structures.

  3. Modeling And Analysis

    • Procedure followed to generate the models

      Fifteen different types of framed steel structure of three story industrial building are modeled. Following parameters are considered

      Table 1: Physical Properties

      Figure 1: Modeling in Staad ProV8i

      Sl.no

      Material

      Steel

      Concrete

      1

      Yield strength

      250 N/mm2.

      2

      Modulus of elasticity

      2×105 N/mm2

      25×103 N/mm2

      3

      Density

      7850 kg/m3

      25 kN/m2

      4

      Grade

      250 N/mm2

      M25

      5

      Poissons ratio

      0.3

      0.2

      Figure 4: Model 3 with bay size 40 m X40 m

      Figure 2: Model 1 with bay size 12 m X12 m

      Fgure 3: Model 2 with bay size 12 m X12 m

      Figure 5: Model 4 with bay size 40 m X40 m

      Figure 6: Model 5 with bay size 40 m X40 m

      Table 3: Calculated Wind Forces

      Sl. No

      Story no.

      Height in m

      F

      kN/m2

      Amount of wind force acting per

      meter on member in kN/m

      1

      1st and 2nd floor

      3.7

      1.5

      5.55

      2

      3rd floor

      1.85

      1.5

      2.775

      3

      1st and 2nd Floor

      3.5

      1.5

      5.25

      4

      3rd floor

      1.75

      1.5

      2.625

  4. CALCULATION OF FORCES

    1. Calculation of wind load

      According to IS 875 (Part III) 1987.

      • Design wind speed, Vz = Vb x k1 x k2 x k3

        Vb = 33 m/s k1 = 1.0

        k2 = 1.10

        k3 = 1.0

        Vz = 33 x 1.0 x 1.10 x 1.0

        Vz = 36.3 m/s

      • Wind pressure, pz = 0.6 x Vz2

        pz = 0..6 x 36.32

        pz = 790.614 N/m2

      • Design wind pressure, pd = kd x ka x kc x pz

        pd = 0.9 x 0.9 x 1 x 790.614 pd = 640.397 N

      • Wind load on individual members, F = (Cpe Cpi) A x pd

    F = (0.7 (-0.2)) A x 640.397

    F = 576.35 A N F = 0.576 kN/m2

    As calculated wind loads are nominal a minimum wind load of

    1.5 kN/m2 is considered for analysis.

    Table 4: Results for Displacements ant relative Displacement

    Plan size in m

    Height in m

    Self-weight in kN

    Displacement in mm

    Relative Displacement in

    mm

    12 x 12

    3.2

    4146.83

    3.368

    1.025

    12 x 12

    3.2

    4082.39

    40.76

    1.84

    40 x 40

    3.2

    41521.33

    37.884

    126.567

    40 x 40

    3.5

    41531.93

    41.426

    551.469

    40 x 40

    3.7

    41538.99

    43.786

    551.469

    12 x 12

    3.2

    4142.45

    63.128

    4.275

    12 x 12

    3.2

    4146.83

    3.423

    1.025

    40 x 40

    3.2

    41521.33

    37.945

    126.567

    40 x 40

    3.5

    41531.93

    41.499

    551.47

    40 x 40

    3.7

    41538.99

    43.868

    551.47

    12 x 12

    3.2

    4142.45

    26.842

    3.711

    12 x 12

    3.2

    4146.83

    3.328

    1.025

    40 x 40

    3.2

    41521.33

    37.917

    126.567

    40 x 40

    3.5

    41531.93

    41.462

    551.14

    40 x 40

    3.7

    41538.99

    43.824

    551.14

    Table 5: Results for Bending Moment and Shear Forces

    Plan size in m

    Height in m

    Beam Force in kN

    Bending moment in kNm

    Shear force in kN

    12 x 12

    3.2

    1888.31

    16.54

    15.90

    12 x 12

    3.2

    1492.79

    387.91

    198.68

    40 x 40

    3.2

    21126.15

    176.71

    53.01

    40 x 40

    3.5

    21122.07

    176.71

    53.01

    40 x 40

    3.7

    21119.4

    176.71

    53.01

    12 x 12

    3.2

    1540.83

    221.90

    69.34

    12 x 12

    3.2

    1914.55

    15.90

    15.90

    40 x 40

    3.2

    21155.24

    176.71

    53.01

    40 x 40

    3.5

    21153.42

    176.71

    53.01

    40 x 40

    3.7

    21152.23

    176.71

    53.01

    12 x 12

    3.2

    1587.43

    455.02

    284.04

    12 x 12

    3.2

    1868.04

    30.65

    17.88

    40 x 40

    3.2

    21142.17

    176.71

    `68.92

    40 x 40

    3.5

    21137.71

    176.71

    66.43

    40 x 40

    3.7

    21134.79

    176.71

    64.92

  5. RESULT AND DISCUSSIONS

    After the analysis significant change in parameters such as node displacement, beam relative displacement, beam end forces, weight and beam forces such as maximum axial forces, bending moments and shear forces of the structure are noticed.

  6. DISCUSSION AND CONCLUSION.

  1. In the first model the connections are fixed. Hence the node displacements observed in this model are minimum.

  2. In the sixth model, the joints are hinged (releases are provided). Here maximum displacements are observed.

  3. In the eleventh model, only the joints where the columns overlap or have a joint are hinged. It is observed that the values of node displacement range between the first and sixth model. All the three models have the same geometry and member sizes.

  4. These trials were taken for different models, different member sizes, different length and span sizes. However the results are similar to first trial.

  5. From the above results, we can conclude that the fixed connections are best suited as the node displacements are minimum and are less than H/250 mm. which is the minimum requirement for a structure to be safe under displacements.

REFERENCES

  1. Tsioupanis Kyriakos, January 2012, Moment Capacity of Simple Steel Connections, Department of Civil Engineering, Frederick University.

  2. Charleys W. Dolan et al., March April 1987, Moment Resistant Connections and Simple Connections, Specially Founded R & D Program, PCI Journal.

  3. Erik Anders Nelson, 2011, Simple Shear Connections-Not So Simple, Structures Congress, ASCE.

  4. Jaswant N. Arlekar and C. V. R. Murty, August 2004, Shear Moment Interaction for Design of Steel Beam to Column Connections, 13th World Conference on Earthquake Engineering Vancouver, B. C., Canada, Paper No. 635.

  5. IS: 875 (Part 1) 1987, Indian Standard, Code of Practice for Design Loads (Other than Earthquake) for Buildings and Structures, For Dead Loads.

  6. IS: 875 (Part 2) 1987, Indian Standard, Code of Practice for Design Loads (Other than Earthquake) for Buildings and Structures, For Imposed Loads.

  7. IS: 875 (Part 3) 1987, Indian Standard, Code of Practice for Design Loads (Other than Earthquake) for Buildings and Structures, For Wind Loads.

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