Experimental Study on Welded Connections for Rectangular Hollow Cold Formed Light Gauge Tension Members Ravindra B. Kulkarni 1 Akhilesh Goje 2

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1 IJSRD International Journal for Scientific Research & Development Vol. 3, Issue 6, 215 ISSN (online): Experimental Study on ed Connections for Rectangular Hollow Cold Formed Light Gauge Tension Members Ravindra B. Kulkarni 1 Akhilesh Goje 2 1 Assistant Professor 2 P.G. Student 1,2 Department of Civil Engineering 1,2 KLS Gogte Institute of Technology, Belagavi Abstract Structural Steel sections are manufactured and transported to some standard specific lengths, as governed by manufacturing, transportation and handling restrictions. However, most of the structural steel members used in structures has to span great lengths and enclose a large threedimensional space. The lengths of the members are required to increase by suitable connection (By Bolted/ed). Thus, connections are essential to create an integral steel structural member.the present study is focused on determining the experimental tests on welded connections for rectangular hollow cold formed light gauge sections. This experimental work presents six experimental tests that have been carried out on 6mmX4mm Rectangular Hollow s (RHS). The experimental tests included Tension tests on Normal s and Butt ed s by varying thickness and also the results are compared to Codal values. It is found that the welded joints have performed well and the Ultimate Capacity of the welded sections is slightly reduced in compare with normal sections. Polynomial equations have been developed using MAT LAB (Polynomial regression). The purpose of this investigation was to study behavior of full Butt welded Connection in Tension for cold formed light gauge RHS. Key words: Cold formed Light Gauge Steel, Butt ed Connection, Tension Member, Pattern I. INTRODUCTION Steel is the most widely used material due to its versatility. 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 budding in its usage. Light gauge steel structural members are cold formed from steel sheet or strips. Various cold formed members are grouped as follows: Framing members, such as beams, studs, joists etc. Floor, wall panels and long span roof deck. Standard roof deck and wall claddings. The thickness for the cold formed framing members generally range from 1.2mm to 4.mm and that of claddings, flooring vary from 1.2mm to 2.5mm. In India Light gauge members are widely used in fabrication of hangers, railway coaches etc., and these members vary in thickness from 1.mm to 3.mm. [1] There are predominantly two practices for manufacturing cold formed light gauge sections: Coldrolling. Pressing in pressbrakes. 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 DETAILS A. Properties of Cold Formed Light Gauge RHS Fig 1: Typical RHS Where, h = Height of the section b = Width of the section t = Thickness of the section r = Radius section Ixx and Iyy = Moment of inertia about x and y axis 1) Mechanical Properties of Cold Formed Light Gauge Steel RHS Grade of Steel = YST 24 Ultimate Tensile Strength = 41MPa Yield Strength = 24MPa = 15% Young s Modulus of Elasticity = 2GPa B. Properties of Electrode 1) Electrode Classification Electrode Confirming to IS code, Electrode code IS: 814, ER ) Mechanical Properties of Electrode Ultimate Tensile Strength = 46MPa Yield Strength = 43MPa = 26% Impact = 62Jmin at C III. DESIGN OF TENSION MEMBERS A. General Tension members are the linear members wherein the axial forces act to cause elongation. These members can sustain loads up to the ultimate load, at which stage they may fail by rupture or yielding at a critical section. These members can elongate nearly about 15% of the original length. Hence, the yield load is usually taken as the limiting load in the design of tension members. [1] The designs of cold formed light gauge steel sections are carried out here using different codes. The codes used for the design study are All rights reserved by 481

2 Experimental Study on ed Connections for Rectangular Hollow Cold Formed Light Gauge Tension Members (IJSRD/Vol. 3/Issue 6/215/111) 1) IS 8:27 Indian standard Code of practice for use of general construction in steel. (As much details are not available in IS 8:1975 on Tension) 2) BS 5951:2 Structural use of steelwork in building Part 1. Code of practice for design of rolled and welded sections. B. Comparative Results for Obtained IS 8:27&BS 5951:2 The calculations involved are done for same sections 6mmX4mm of different thicknesses. Following are the results for laterally unsupported beams using IS 8:27 and BS 5951:2 Thickness IS 8:27 BS 5951:2 t Max w Max w Table 1: Comparative results for IS 8:27 and BS 595 1: 2 6x4x x4x x4x x4x Table 2: Experimental Results Butt ed Light Gauge B Area of section (mm 2 ) Ultimate at peak load 6x4x x4x Table 3: Experimental Results for Normal (Without Butt ) D. Setup of Channel Mould for Tensile Test Channel section moulds are used to transfer the load from a 1kN UTM to rectangular hollow section (RHS). Moulds are fabricated from 2mm thick mild steel plates with 2mm mild steel bar. They made such that it can be inserted inside RHS specimen. The set of moulds, had holes of 18mm diameter at appropriate pitch on a 1mm plate attached to 2mm thick plate having 2mm diameter bar connected to it. E. Graph Showing Behavior of Cold Formed Light Gauge for Butt on Tension test Fig. 1: Graph 1: Comparative results for IS 8:27 and BS 5951:2 IV. EXPERIMENTAL PROCEDURES AND RESULTS FOR TENSION MEMBERS A. General A member subjected to tension undergoes elongation and results in tensile stresses. Several mechanical properties of the materials that are important in the design are determined by tension test. The specimens are tested up to ultimate capacities and elongations are recorded at frequent intervals. [9] B. Test setup and Procedure All the experimental tests have been carried out on Universal Testing Machine. The RHS specimen of length 5mm were fastened to Channel section moulds, the setup was placed in Universal Testing Machine and then secured fast grips in Universal Testing Machine grippers. Using 1kN capacity hydraulic jack and a load cell tensile force were applied onto the test specimens. and elongations of the specimens were then recorded at an elongation interval of 1mm, which was recorded directly on UTM. C. Experimental Results for Tension members A Area of section (mm 2 ) Ultimate at peak load Fig. 2: Graph 2: v/s for same cross section with different thickness for Butt ed section Fig. 3: Graph 3: Stress v/s Strain for same cross section with different thickness for Butt ed section All rights reserved by 482

3 F. Graph Showing Behavior of Cold Formed Light Gauge for Normal (Without Butt ) on Tension Test Experimental Study on ed Connections for Rectangular Hollow Cold Formed Light Gauge Tension Members (IJSRD/Vol. 3/Issue 6/215/111) Fig. 4: Graph 4: v/s for same cross section with different thickness for Normal (Without Butt ) Fig. 6: Graph 6: Comparison in carrying capacity H. Graph Showing Behavior of Cold Formed Light Gauge for Different Thicknesses Fig. 5: Graph 5: Stress v/s strain for same cross section with different thickness for Normal (Without Butt ) G. Comparative Experimental Results and Modes of Butt ed Normal (Without Butt ) Thick ness Max at Max Mode of Observed Yielding + Rupture Yielding + Rupture Table 4: Comparison in load carrying capacity and observed modes of failure Fig. 7: Graph 7: v/s for Tension test on cross section 6x4x1.6 for Normal (Without Butt ) and Butt ed Fig. 8: Graph 8: v/s for Tension test on cross section 6x4x2. for Normal (Without Butt ) and Butt ed I. Developing polynomial equation using MAT LAB (Polynomial regression) for Tension members 1) General By using MAT LAB (Polynomial regression) we can work on polynomial regressions, which are also known as polynomial least squares fittings. It develops the polynomial function for a given set of data points, for the relation between several variables. The Residual sum of squares for any obtained polynomial equation should be minimum. [11] All rights reserved by 483

4 Experimental Study on ed Connections for Rectangular Hollow Cold Formed Light Gauge Tension Members (IJSRD/Vol. 3/Issue 6/215/111) Polynomial equations obtained from MAT LAB for Normal (without butt weld) and Butt ed for Tension members are given below. Th k mm Momen t of Inertia (mm 4 ) Elongatio n Loa d Calculate d load Erro r X1 X2 X3 Y Y Table 5: Maximum loads for various thicknesses obtained by polynomial equation for butt weldedsection 2) RESULT: Y = X X X3 Residual Sum of Squares (RSS): Thk mm Mome nt of Inertia (mm 4 ) Calculat ed load Err or X1 X2 X3 Y Y Table 6: Maximum loads for various thicknesses obtained by polynomial equation for normal section (without butt weld) 3) RESULT: Y = X1 Residual Sumof Squares (RSS): J. Reduction in Deflection and Carrying Capacity for Tension Members 6x4x1. 6 6x4x2. Loa d kn Normal Elonm m Butt ed Loa d kn Elo n m m % % Reducti Reductio on n in in Elong 7.17 % 9.55% % 24. % 6x4x % 6x4x % Table 7: Reduction in Deflection and carrying capacity for Tension test V. FAILURE PATTERNS Fig. 9: failure without significant yielding of the specimen C1 Fig. 1: failure without significant yielding of the C2 Fig. 11: failure without significant yieldingof the specimen C3 All rights reserved by 484

5 Experimental Study on ed Connections for Rectangular Hollow Cold Formed Light Gauge Tension Members (IJSRD/Vol. 3/Issue 6/215/111) VI. RESULTS AND DISCUSSIONS 1) There is reduction in the load capacity of the section due to full butt welded joint i.e. by 7% to 1% less when compared to the normal section. 2) The normal sections have failed due to yielding and rupture. 3) The failure has taken place in full butt welded joint due to weld failure irrespective of thickness of the section. 4) There is reduction in the elongation for welded section compared to the normal section Fig. 12: failure without significant yieldingof the specimen C4 Fig. 13: Yielding and Rupture failure of the specimenof the specimen D1 Fig. 14: Yielding and Rupture failure of the specimen of the specimen D2 VII. CONCLUSION 1) The failure takes place only at welded joint and the tension capacity reduced to about 7% to 1% compared to normal section. 2) There is reduction in the elongation due to weld. 3) The full butt weld provided to the section is sufficient to take the full strength of the section, no additional strengthening required ACKNOWLEDGMENT 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 [2] Indian standard IS 81:1975, Code practice for use of coldformed light gauge steel structural member s in general building construction. [3] Indian standard IS 8:27, Code practice for general construction in steel. [4] British Standard BS5955:1998, Structural use of steel work in buildingpart 5. Code practice for design of coldformed thin gauge sections. [5] British Standard BS5951:2, Structural use of steel work in buildingpart1. Code practice fordesign ofrolled and welded sections. [6] Zhao, X. L. and Hancock, G. J. (1994a),"Butt s and Fillet s in Thin ColdFormed RHS Members", Tubular Struct. VI, Balkema, Rotterdam, [7] Zhao, X. L. and Hancock, G. J., (1993b),"Longitudinal Fillet s in Thin ColdFormed RHS Members", Research Report, R682, School of Civil and Mining Engineering, The University of Sydney, Sydney, Australia. [8] Zhao, X. L., and Hancock, G. J. (1996), ed connections in thin coldformed rectangular hollow sections. Connections in Steel Structures III, R. All rights reserved by 485

6 Bjorhovde, A. Colson, and R.Zandonini, Pergamon, Oxford, [9] WeiWen Yu, Ph.D., P.E. Cold Form Steel Design Curators Professor Emeritus of Civil Engineering Director, Center for ColdFormed Steel Structures University of MissouriRolla (2). [1] Lip H Teh and Gregory J Hancock. (21), Strength of Fillet ed Connections in G45 Sheet Steels, Research Report No. R82, Centre for Advanced Structural Engineering, The University of Sydney, Sydney, Australia. [11] R. B. Kulkarni, Sahebgoda Biradar, Experimental Study of Cold Formed Light Gauge Rectangular Steel Tubes with Infilled Concrete Beams July 213. Experimental Study on ed Connections for Rectangular Hollow Cold Formed Light Gauge Tension Members (IJSRD/Vol. 3/Issue 6/215/111) All rights reserved by 486