Experimental Investigation on Cold formed Light Gauge channel Section with Welded Knee Joints

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

Experimental Investigation on Cold Formed Light Gauge Channel Section with Welded Knee Joints Ravindra B. Kulkarni1 Shamantha Krishna K2 1 Assistant Professor2P.G. Student 1,2 Department of Civil Engineering 1,2 KLS Gogte Institute of Technology, Belagavi Abstract— The present study is focused on determining the experimental tests on welded knee connections for Light gauge cold formed channel sections. In this paper, there are seven experiments conducted on 100x60x15x2mm Channel sections. The experimental tests included flexural tests on Full welded sections with various Beam Column Knee joint connections and the results were compared to codal values. It is found that the Knee plate welded connection has given high strength for the connection with full all-round welded knee leg size of S=d, beyond that the increase is small. Hence Knee Plate size of S=d is ideal. This type of connection gives the maximum Moment capacity before buckling failure.

Key words: Cold-Formed Light Gauge Channel Sections, Welded Connection, Flexural members I. INTRODUCTION Steel is the most widely used material due to its flexibility.

Structural steel built up members may be grouped into two categories; hot rolled steel and cold formed light gauge steel.

Hot rolled steel has gained its familiarity but cold formed steel is growing in its usage. Light gauge steel structural members are cold formed from steel sheet or strips. Various cold formed members are grouped as follows: 1) Framing members, such as beams, studs, joists etc.

2) Floor, wall panels and long span roof deck.

3) Standard roof-deck and wall-claddings.

The thickness for the cold formed framing members generally ranges from 1.2mm to 4.0mm and that of claddings and floorings vary from 1.2mm to 2.5mm. In India, Light gauge members are broadly used in fabrication of hangers, railway coaches etc., and these members vary in thickness from 1.0mm to 3.0mm. [1] There are predominantly two practices for manufacturing cold formed light gauge sections: 1) Cold-rolling.

2) Pressing in press-brakes.

Cold formed members can be processed by two ways of rolling and press braking with higher limitation of 12.5mm from strips and flats. Cold rolling is most economically for mass requirement of the members while for minimal requirement one can shift to press braking. A connection of members is carried out by cold rivets, bolts and other connecting facility. [1]

II. MATERIAL PROPERTIES A. Properties of Cold-Formed Light Gauge Channel Sections:

Fig. 1: Typical Cold-Formed channel Section Where, B = Breadth of the section D = Depth of the section t = Thickness of the section Ixx and Iyy = Moment of Inertia about x and y axis Zxx and Zyy = Section Modulus about x and y axis Rxx and Ryy = Radius of Gyration about x and y axis 1) Mechanical Properties of Cold-Formed Light Gauge Channel Sections:  Grade of Steel = YST 240  Ultimate Tensile Strength (UTS) = 410Mpa  Yield Strength = 240Mpa  Elongation = 44%  Young’s Modulus of Elasticity = 200Gpa B. Properties of Electrode: 1) Electrode Classification: Electrode Confirming to IS code, Electrode code IS: 814, ER 4211 2) Mechanical Properties of Electrode:  Ultimate tensile strength =460Mpa  Yield Strength=430Mpa  Elongation=25%  Impact=62Jmin at 0oC III. CALCULATION OF FLEXURAL MEMBER STRENGTH A. General: Beams are used to transfer the loads and moments to the columns. There are many sections in ‘cold-formed’ light gauge sections used as flexural members such as Tubular sections, Z-elements, I-elements, Channel elements, Angle sections, Hat sections, T-sections, Deck sections, panel elements etc. The beam will show lateral torsional-buckling, if the compression flange is free to buckle in sideways direction and hence the beam acts as a laterally-Unsupported beam. If the transverse loads in the beam increases, then its plastic moment capacity increases. Laterally supported beam exhibits this type of behavior.

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Experimental Investigation on Cold Formed Light Gauge Channel Section with Welded Knee Joints (IJSRD/Vol. 4/Issue 04/2016/293)

The analysis of Cold-formed light gauge sections is worked out using different codes for the Design of Flexural members. The codes used for the study are; 1) IS: 801-1975 Indian Standard Code of Practice for the use of ‘Cold-formed’ light gauge steel member’s in general building construction.

2) BS: 5950-5:1998 Structural use of steelwork in buildingpart 5. Code of practice for the design of Cold-formed’ thin light gauge sections.

B. Comparative Results For Obtained Is 800:2007: The calculations involved are done for all seven model sections 100x60x15mm of same thicknesses (2mm), but with different joint connections. Following are the results for laterally supported beams using IS 800:2007 with experimental values; Failure Ultimate Buckling Sl No. Buckling Failure load (kN) Load(kN) Load (kN) Model24.3 22.8 19.95 1 Model32.8 31.6 19.95 2 Model46.7 46.7 19.95 3 Model35.8 40 19.95 4 Model43.6 61.9 19.95 5 Model54.7 64.5 19.95 6 Model58.1 71.7 19.95 7 Table 1: Comparative results for BS 5950-1:2000 with Experimental results of all models C. Comparative Results For Obtained BS 5950-1:2000: The calculations involved are done for all seven model sections 100x60x15mm of same thicknesses (2mm), but with different joint connections. Following are the results for laterally supported beams using BS 5950-1:2000 with experimental values; Failure Ultima Workin Maximum Plastic Sl Bucklin te g @ Yield load(K N g Failure load(K load(KN) N) for o Load(k Load N) for for fy Zpxfy N) (kN) 0.6fy 1 24.3 22.8 11.3 18.9 40 2 32.8 31.6 11.3 18.9 40 3 46.7 46.7 11.3 18.9 40 4 35.8 40 11.3 18.9 40 5 43.6 61.9 11.3 18.9 40 6 54.7 64.5 11.3 18.9 40 7 58.1 71.7 11.3 18.9 40 Table 2: Comparative results for IS 800:2007 with Experimental results of all models

can be determined. In this flexural test, tensile load is applied to the specimen thereby calculating the buckling and ultimate load.

B. Test Setup and Procedures: All the experimental tests have been carried out on Universal Testing Machine. The Channel Section specimen of length 250mm were connected to U- shaped moulds, the setup was placed in Universal Testing Machine and then held with flat grips in Universal Testing Machine grippers. Using 1000kN capacity hydraulic jack and a load cell tensile force were applied onto the test specimens. Load and elongations of the specimens were then recorded at an elongation interval of 1mm, which was recorded directly on UTM.

Fig. 2: All Round Weld

Fig. 3: All Round Diagonal Weld

Fig. 4: All Round Diagonal Weld with stiffener plate

Fig. 5: All Round Weld with 50mm Stiffener Knee Plate

IV. EXPERIMENTAL PROCEDURES AND RESULTS A. General: An element subjected to bending undergoes buckling and deformation. The bending stress of the element at any load

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Experimental Investigation on Cold Formed Light Gauge Channel Section with Welded Knee Joints (IJSRD/Vol. 4/Issue 04/2016/293)

Fig. 6: All Round Weld with 75mm Stiffener Knee plate

Fig. 7: All Round Weld with 100mm Knee plate Fig. 11: Buckling and Tearing of Model-5, 6, 7 V. RESULTS AND DISCUSSIONS

Fig. 8: All Round Weld with 110mm Knee plate C. Failure Pattern of All Models:

Fig. 12: Graph. 1: Load Vs Deformations of models with stiffener knee plate

Fig. 9: Buckling and Tearing of Model-1 and Model-2

Fig. 13: Graph. 2: Load Vs Deformations of all models Fig. 10: Tearing of Model-3 and Model-4

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Experimental Investigation on Cold Formed Light Gauge Channel Section with Welded Knee Joints (IJSRD/Vol. 4/Issue 04/2016/293)

1) The full weld provided in the section has not at all failed and always failed at leg sections only.

2) The sections with Knee stiffener plate connections showed a maximum load carrying capacity compared to others.

3) The diagonal stiffener plate connection with all round weld showed a maximum load of 47.6kN before failing.

4) The knee plate of full leg size welded connection with all round weld has taken a maximum buckling load of 54.7kN.

[9] IS: 801-1975 Indian Standard Code of Practice for the use of Cold-formed light gauge steel member’s in general building construction.

[10] BS: 5950-5:1998 Structural use of steelwork in buildingpart 5. Code of practice for the design of Cold-formed thin light gauge sections.

VI. CONCLUSIONS 1) The failure took place only at leg of the sections.

2) The section with Diagonal stiffener plate with all round weld is a ideal connection.

3) The knee plate welded connection has taken a maximum load when the size of leg is equal to the depth of web and beyond that increase is small 4) Hence this type of connection takes maximum load before buckling failure.

ACKNOWLEDGEMENT 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.

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