Experimental Investigation on Cold Formed Light Gauge Rectangular Hollow Section with Welded Knee Jo

IJSRD - International Journal for Scientific Research & Development| Vol. 4, Issue 04, 2016 | ISSN (online): 2321-0613

Experimental Investigation on Cold Formed Light Gauge Rectangular Hollow Section with Welded knee Joints Ravindra B. Kulkarni1 Zuarker Rajesh Shripad2 1 Assistant Professor 2P.G. Student 1,2 Department of Civil Engineering 1,2 KLS Gogte Institute of Technology, Belagavi Abstract— The most of the structural steel members used in structures has to span great length and surround a large three-dimensional space. The lengths of the members are required to increase by suitable connection (By Bolted/ Welded). Thus, connections are needed to form an important steel structural member. Very less work is done in welded connections in Cold formed Light sections. The present study is motivated on determining the experimental tests on welded Connections for Light gauge cold formed Rectangular hollow sections. In this project, there are seven experiments conducted on 60mmx40mmx1.6mm Rectangular hollow Sections. The experimental tests included flexural tests on full welded sections with various types beam column joint connections and the results were compared to codal values. It is found that, the knee plate welded connection with full all-round with knee plate leg size of S=1.5d has given high strength. Hence there is increase of load with increase of leg size of knee plate. This type of connection has got higher moment capacity.

Key words: CFLG, Welded knee Joints I. INTRODUCTION Now days, Cold Formed Light Gauge steel (CFLG) elements are widely used in the construction of steel structures. CFLG elements are manufactured in the form of hot rolled sections to coils and strips with galvanised coatings. Light-gauge Steel elements are used for making steel strips or sheets. Light-gauge elements that are manufactured by bending a flat sheet at normal temperature takes more load or gives great support compared to that of flat strips. There are varieties of Light-gauge elements which can be divided into; 1) Framed elements such as joists, studs, beam etc.

2) Floor, Wall-panels and long-span roof-decks.

3) Wall-claddings and Standard roof-decks.

The thickness for cold-formed framing elements generally vary from 1.2mm to 4.0mm. The thickness of floor, wall-panel sections and for long span roof-deck differs from 1.2mm-2.5mm. The thickness of wall claddings and standard roof deck ranges from 0.8 to 1.2mm. Light-gauge elements are widely used in India, for the construction of Bus-bodies, coaches of railways etc. They vary in their thicknesses from 1mm-3mm. [1] There are mainly two practices for manufacturing the Lightgauge sections: 1) Cold-rolling 2) Pressing in press-brakes.

Light-gauge elements are manufactured in factories by the process of Cold-rolling and Press-Braking of flat strips which are not more than 12.5mm thickness. For mass productions, these elements are done very carefully by ColdRoll and for fewer productions; these elements are formed economically by press brakes. These elements are connected

together by spot, fillet, plug or slot welds, by screws, bolts, cold rivets, or by special fasteners.

II. MATERIALS DETAILS A. Properties of Cold-Formed Light-Gauge RHS

Fig. 1: Typical-RHS Where B = Breadth of the segment D = Depth of the segment t = Thickness of the segment Ixx= Moment of inertia around x axis Iyy = Moment of inertia around y axis Zxx= Section Modulus around x axis Zyy = Section Modulus around y axis Rxx= Radius of Gyration around x axis Ryy= Radius of Gyration around y axis B. Mechanical Properties for ‘Cold-Formed’ Light-Gauge RHS ‘Grade-steel’ = YST 235 (As per IS: 4923:1997) ‘Ultimate-Tensile-Strength’ = 410MPa ‘Yield-Strength’ = 240 MPa ‘Elongation’ = 20% ‘Young’s-Modulus-Elasticity’ = 200GPa C. Properties of Electrodes Electrode Confirming to IS code, Electrode code IS: 814, ER 4211 ‘Ultimate-tensile-Strength’ = 460MPa ‘Yield-Strength’ = 430MPa ‘Elongation’ = 20 % ‘Impact’ = 62Jmin at 00C III. DESIGN OF FLEXURAL STRENGTH OF MEMBER A. General Beam-column joints are subjected to shear and moment.

‘Cold-formed’ light gauge steel sections are used as Tubular sections such as I, Z- sections, Channels and Angles etc.

The CFLG Sections subjected to flexural compressive stresses at joints leads to local buckling in addition to

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Experimental Investigation on Cold Formed Light Gauge Rectangular Hollow Section with Welded knee Joints (IJSRD/Vol. 4/Issue 04/2016/276)

longitudinal torsional buckling. The analysis of ‘coldformed’ sections is done using Codal provisions.

1) ‘IS-801-1975’ IS code is meant for ‘Light-gauge’ cold formed for structural elements for general ‘Building-construction’ 2) ‘BS5950-5-1998’ This BS code is used for ‘cold-formed Light gauge thin sections for steel work in ‘Building-construction’ B. Comparative Results for Obtained IS 800:2007 The calculations involved are done for all seven model sections 60x40x1.6mm but with different joint connections.

Following are the results for laterally supported beams using IS 800:2007 with experimental values; SR . no.

1 2 3 4 5 6 7

Failure Buckling Load(kN ) 8.8 12.9 19.3 11.8 13.2 17.5 21.5

Ultimat e failure Load (kN) 5.2 7.8 19.3 16 21.7 40.1 45.5

Working load(kN ) for 0.6fy 2.94 2.94 2.94 2.94 2.94 2.94 2.94

Maximum @ Yield load(kN) for fy 4.88 4.88 4.88 4.88 4.88 4.88 4.88

Plastic load(kN ) for Zpxfy 5.0 5.0 5.0 5.0 5.0 5.0 5.0

Fig. 2: All-round Butt/fillet weld

Fig. 3: All-round Butt/fillet Diagonal weld

Table 1: Comparative Results for Obtained IS 800:2007 C. Comparative Results for Obtained BS:5950-1:2000 The calculations involved are done for all seven model sections 60x40x1.6mm but with different joint connections.

Following are the results for laterally supported beams using BS 5950-1:2000 with experimental values SR.no.

Model1 Model2 Model3 Model4 Model5 Model6 Model7

Failure Buckling Load(kN) 8.8 12.9 19.3 11.8 13.2 17.5 21.5

Ultimate failure Load (kN) 5.2 7.8 19.3 16 21.7 40.1 45.5

Buckling load(kN) 4.52 452 4.52 4.52 4.52 4.52 4.52

Fig. 4: All round weld with Diagonal Stiffener plate

Table 2: Comparative Results for Obtained BS: 5950-1:2000 IV. EXPERIMENTAL PROCEDURE AND RESULTS FOR FLEXURAL-ELEMENTS A. General A member subjected opening moments (tension) undergoes Buckling & tearing. Using the formulae from IS 801:1975 &BS 5950-5:1998 we get Moment & Safe load. The maximum vertical load is applied by UTM consists of loading point located at two equally symmetric point loads.

The bending moments at the joints are calculated & also the Maximum loads.

Fig. 5: All round weld with 30mm Knee Stiffener plate

B. Test setup and Procedure All the experimental tests were carried out on Universal Testing Machine of 1000kN capacity. The RHS specimen size was (60mm x 40mm x 1.6mm), and applied load through clamps & bolts inserted in the webs of RHS, which produces opening bending moments (tension) about the joint centre line. Deflection & load applied on the specimen were recorded on UTM, interval of deflection was 0.5mm.

Fig. 6: All round weld with 45mm Knee Stiffener plate

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Experimental Investigation on Cold Formed Light Gauge Rectangular Hollow Section with Welded knee Joints (IJSRD/Vol. 4/Issue 04/2016/276)

Fig. 7: All round weld with 60mm Knee Stiffener plate

Fig. 11: Buckling & tearing of model no.5 & model no.6

Fig. 8: All round weld with 60mm Knee Stiffener plate C. Failure Patterns of all Models

Fig. 12: Buckling & tearing of model no.7 V. RESULTS & DISCUSSION

Fig. 9: Buckling & tearing of model no.1 & model no.2

Fig. 10: Buckling & tearing of model no.3 & model no.4

Fig. 13: Graph 1: Four Model with Knee plate connections of Deformation Vs. load Four models Load Vs. Deformation is plotted as shown above; The pattern of the curves are nearly same for all leg sizes, but the maximum load increase with the increase in the leg size.

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Experimental Investigation on Cold Formed Light Gauge Rectangular Hollow Section with Welded knee Joints (IJSRD/Vol. 4/Issue 04/2016/276)

Fig. 13: Graph 2: All models Deformation vs. load Deformation v/s Load of all models is plotted as shown above; 1) Model-1- Full weld connection- In this Model, The curve increases linearly till the maximum buckling load i.e8.8kNand the connection fails due to failure of weld at 5.2kNafter large deformation.

2) Model-2- Full weld with diagonal connection- In this Model, The curve increases linearly till the maximum buckling load of the material i.e12.9kNand the connection fails at 7.8kNdue to failure of the weld.

3) Model-3- Full weld with diagonal stiffener plate- In this Model, there is a sharp increase in the curve till buckling of the member at 19.3kN. At this 19.3kNmaximum load, the failure of the weld due to tearing takes place.

4) Model-4 – Full Weld with 30mm Knee Stiffener PlateIn this Model, The curve increases linearly till the buckling load of 11.8kN.The peak load16kNat which the connection fails due to tearing of weld and knee plate after large deformation.

5) Model-5-Full Weld with 45mm Knee Stiffener Plate- In this Model, The curve increases linearly till the buckling load of 13.2kN.The peak load 21.7kN at which the connection fails due to tearing of weld and knee plate after large deformation..

6) Model-6- Full Weld with 60mm Knee Stiffener PlateIn this Model, The curve increases linearly till the buckling load of 17.5kN.The knee plate and weld fails at peak load of 40.1kN after large deformations and buckling.

7) Model-7 Full Weld with 60mm Knee Stiffener Plate- In this Model, there is a sharp increase in the curve till buckling of the member at 21.5. The knee plate fails at peak load of 45.5kNafter large deformations and buckling.

VI. CONCLUSION The welded framed cold formed light gauge connection between the same RHS sections with alternate method have been experimentally tested with the existing facility. The connection in applied load as shown in figure induces flexural stress and shear stress and also tensile stress. The graphs have been plotted for the deformation in radians to

the vertical loads in kN. From the above results and discussions, we conclude that: 1) The full strength fillet/butt weld provided has not failed in all the models and always failure took place in the leg sections only.

2) The Model No.3 with diagonal stiffener plate with full welded all-round connection is very ideal. The Curves shows the maximum buckling load of 19.3kN before failure. The buckling/tearing of weld which occurs simultaneously at that load compared to Model-1 and Model-2.

3) The Knee plate welded connection with full all-round weld Model no’s 4, 5,6and 7 Knee plate leg size (S=0.5d, 0.75d, 1.0d, 1.5 d) maximum Buckling load is 21.5kN in Model No.7 where Knee leg size is S=1.5d. .

Hence there is increase of load with increase of leg size of Knee Plate. This type of connection has got higher Ultimate load failure.

ACKNOWLEDGMENTS I would like to add a few heartfelt words for the people who have been part of this dissertation by supporting and encouraging me. At the onset, I would like to thank ALMIGHTY. I would also like to express my Deepest Gratitude to my guide Prof.R.B.Kulkarni, Civil Department, KLS Gogte Institute of Technology, Belagavi, Karnataka, India for supporting me during dissertation work and guiding me with his valuable suggestions. Last, but not the least, I would like to thank my friends who provided me with valuable suggestions to improve my dissertation.

Finally I attribute all my success in life to My Parents for their moral and intellectual support. It is my greatest pleasure to dedicate this achievement to My Parents.

REFERENCES [1] Dr.B.C.Punmia, Ashok Kumar Jain, Arun Kumar.Jain, “Design of Steel Structures”, Jan 1998, page 561-600.

[2] Indian Standard IS 801:1975, “Code practice for use of cold-formed light gauge steel structural members in general building construction”.

[3] American Iron & Steel Institute, Specification for the design of Light Gauge Steel Structural members, New York, N.Y., Published 1946.

[4] Journal of the Structural Division, ASCE, Volume 85, No.ST9, Cold formed, Light Gauge Steel construction, Published 1959.

[5] American Iron & Steel Institute, Load & Resistance Factor Design Specification for Cold-Formed Steel Structural Members, Washington, D.C. Published 1991.

[6] American Iron & Steel Institute, specification for the Design of Cold-Formed Steel Structural Members, Washington, D.C. Published 1996.

[7] American Iron & steel Institute, North American Specification for the Design of Cold-Formed Steel Structural Members, Washington, D.C. Published 2001.

[8] American Iron & steel Institute (2007). North American Specification for the Design of Cold Formed Steel Structural Members, Washington, D.C. [9] Wei-Wen Yu, John Wiley & Sons Inc. (2000). Cold Formed Steel Design, John Wiley & Sons, New-york, NY.

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Experimental Investigation on Cold Formed Light Gauge Rectangular Hollow Section with Welded knee Joints (IJSRD/Vol. 4/Issue 04/2016/276)

[10] J. Rhodes and R.M.Lawson, “Design of structures using Cold Formed Steel sections”. SCI publication 089, the steel construction Institute, U.K.1992 Indian Standard IS 801:1975 “Code of practice for use of Cold Formed Light GaugeSteelStructural members in general building construction”. Bureau of Indian Standards, New Delhi (1976).

[11] Tim Wilkinson, Gregory J. Hancock, “Tests of Knee joints in Cold Formed Rectangular Hollow sections”.

Research Report No. R779, December 1998, The University of Sydney, Department of Civil Engineering, Centre for Advanced Structural Engineering, Sydney, Australia.

[12] Lip H. Teh, Gregory J. Hancock, “Improving Rotation Capacities of Stiffened Welded Knee Joints between DuraGal C450 RHS”, Research Report No. R832, September 2003, the Department of Civil Engineering, Centre for Advanced Structural Engineering, Sydney, Australia.

[13] Xiao Ling Zhao, Gregory J. Hancock, (1995a). “Butt welds & Transverse Fillet welds in thin Cold-Formed RHS members”. J. Struct. Engrg., ASCE, 121(11), 1674-1682.

[14] Xiao Ling Zhao, Gregory J. Hancock, (1995b).

“Longitudinal Fillets welds in thin Cold-Formed RHS members”. J. Struct. Engrg., ASCE, 121(11), 16831690.

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