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An Investigation on the Behavior of Bolted Connections using Friction Drilling in Shear and Tension

Ashrafi, Abolfazl | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47443 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Ahmadizadeh, Mehdi
  7. Abstract:
  8. Friction drilling or flow drilling is a method of making holes in metal sheets, in which the material is pushed with the aid of heat from friction. This procedure allows making holes in sheet metal, with a sleeve formed as the hole is created. This sleeve is then threaded and used as the nut, thus eliminating the need for access to the interior faces of hollow steel sections. On the other hand, with the development of advanced manufacturing techniques, larger and thicker hollow structural sections are becoming more popular in mid-rise and multistory structures. onsequently, flow drilling can be considered as a viable alternative for traditional drilling techniques, where the material is basically wasted and access to the interior of these sections is required for bolted connections.Unlike the traditional bolt-nut connections, the sleeve used as nut in flow drilling has properties similar to theplate. As a result, a different behavior is expected compared to traditional connections, where nuts are usually made of high-strength steel.In this study, the structural behavior of this type of connections is investigated through previously-established experimental results and their extensions by numerical modeling. The bearing and tension behavior of bolted flow drill connections have been studied in comparison with traditional connections using advanced finite element modeling and analysis. For this purpose, shear and tension bolted connections have been modeled, each in both cases of traditional and friction drilling methods. The numerical models are first validated against the existing experimental data, and then extended and used to derive their structural properties. The results show that flowdrill connections have a higher bearing strength originating from the sleeve formed around the holes. These overstrengths have been observed to reach up to 1.7 times those of the equivalentordinary connections, depending on bolt diameter and plate thickness. In contrast, the tension strength of flowdrill connectionshave been observed to be less than those of their traditional equivalents, mainly due to stripping of threads created in sleeves. The corresponding strength reduction factors may be as low as 0.55 in thinner plates. Finally, relations for simple calculation of correction coefficients have been established that can be used in conjunction with code relations for design of flow drill connections
  9. Keywords:
  10. Finite Element Modeling ; Tensile Strength ; Bolted Connection ; Friction Drilling ; Bearing Type Connections ; Bearing Strength

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