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Unformatted text preview: WELDS-STATIC AND FATIGUE STRENGTH-II 31 WELDS- STATIC AND FATIGUE STRENGTH – II 1.0 INTRODUCTION In the previous chapter, a detailed account of various welding processes, types of welds, advantages of welded connections etc. were presented. It was seen that welded connections are continuous and more rigid when compared to bolted connections. It was also pointed out that fillet welds and butt welds constitute respectively 80% and 15% of all welds in the construction industry; the balance 5% is made up by plug, slot and spot resistance welds. In this chapter, the behaviour and design of welded connections under various static loading conditions is considered. A typical connection design process is initiated with the design, which is followed by the welding operation and, concludes with inspection. 2.0 CONNECTION DESIGN In the design of connections, due attention must be paid to the flow of the force through the connection. The transfer of forces should occur smoothly, without causing any stress concentration or cracks. The connections can be either concentric or eccentric. In concentric connections, the forces acting on the connections will essentially be axial in nature, whereas in eccentric connections, the axial forces will be coupled with bending or torsion. These types of connections are described in the following. 2.1 Concentric connections Static strength of a welded joint depends upon the following factors • Type and size of the weld • Manner of welding, and • Type of electrode used. A primary responsibility of a designer is to select the type and size of the weld. A number of varieties of welds are available. When it is properly chosen with the correct electrode, it develops full strength of the parent material. The chosen type of weld should develop minimal residual stresses and distortions. As stated in the introduction, butt and fillet welds are the usual forms of welds in practical building construction. Butt welds are used at an edge-to-edge junction or a tee junction. A butt weld connection is made by bringing the plates to be joined face to face edgewise and then filling the cavity formed by edge preparation or by just penetrating the unprepared junction. Butt welds can be either full penetration or partial penetration. © Copyright reserved Version II 31-1 WELDS-STATIC AND FATIGUE STRENGTH-II Partial penetration butt welds may be used for static loading, if reduced strength is acceptable. On the other hand, a fillet weld is made away from the edges of the abutting plates. The joint is formed by welding the members in an overlapped position or by using a secondary joining material. The main advantage of a fillet weld is that the requirements of alignment and tolerance are less rigorous when compared to butt welds. Fillet welding could be applied for lap joints, tee joints and corner joints. A detailed description of these two types of welds and their design requirements are presented in the following....
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This note was uploaded on 03/14/2012 for the course CIVIL 101 taught by Professor Reddy during the Spring '12 term at Andhra University.
- Spring '12