Block shear fialure mode of axially loaded group of screws

Research output: Contribution to conference(Old data) Lecture or PresentationResearch

Abstract

Self-tapping screws are efficient and flexible fasteners, applicable for many types of connections. Investigations on axially loaded groups of screws pointed out, that small spacing between the screws lead to block shear failure mode. So far, block and plug shear failure mode are only analysed for laterally loaded fasteners. Corresponding models cannot be simple transferred to primary axially loaded screws, because of their load insertion continuously along the effective thread featuring a thread-fibre angle perpendicular or with an angle to grain. Results gained by means of two different test configurations, with constant 90° thread-fibre angle but different configurations of group of screws and support conditions are presented. A block shear model is presented, and for mean values for stiffness and strength properties as model parameters are discussed together with values for parameters related to the force distribution over the effective thread length for the first test configuration. Agreement between model and test results was found on a conservative basis. As outlook, considerations of additional bending stresses as well as parameter optimisation are seen as prerequisites and next steps for further model improvement and practicality.
Original languageEnglish
Publication statusPublished - 23 Aug 2016
EventWorld Conference on Timber Engineering - Universität Wien, Wien, Austria
Duration: 22 Aug 201625 Aug 2016
http://wcte2016.conf.tuwien.ac.at/home/

Conference

ConferenceWorld Conference on Timber Engineering
Abbreviated titleWCTE 2016
CountryAustria
CityWien
Period22/08/1625/08/16
Internet address

Fingerprint

Fasteners
Failure modes
Lead screws
Fibers
Stiffness

Keywords

  • block shear
  • screw group

Cite this

Block shear fialure mode of axially loaded group of screws. / Mahlknecht, Ursula; Brandner, Reinhard; Augustin, Manfred.

2016. World Conference on Timber Engineering, Wien, Austria.

Research output: Contribution to conference(Old data) Lecture or PresentationResearch

Mahlknecht, U, Brandner, R & Augustin, M 2016, 'Block shear fialure mode of axially loaded group of screws' World Conference on Timber Engineering, Wien, Austria, 22/08/16 - 25/08/16, .
Mahlknecht U, Brandner R, Augustin M. Block shear fialure mode of axially loaded group of screws. 2016. World Conference on Timber Engineering, Wien, Austria.
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T1 - Block shear fialure mode of axially loaded group of screws

AU - Mahlknecht, Ursula

AU - Brandner, Reinhard

AU - Augustin, Manfred

PY - 2016/8/23

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N2 - Self-tapping screws are efficient and flexible fasteners, applicable for many types of connections. Investigations on axially loaded groups of screws pointed out, that small spacing between the screws lead to block shear failure mode. So far, block and plug shear failure mode are only analysed for laterally loaded fasteners. Corresponding models cannot be simple transferred to primary axially loaded screws, because of their load insertion continuously along the effective thread featuring a thread-fibre angle perpendicular or with an angle to grain. Results gained by means of two different test configurations, with constant 90° thread-fibre angle but different configurations of group of screws and support conditions are presented. A block shear model is presented, and for mean values for stiffness and strength properties as model parameters are discussed together with values for parameters related to the force distribution over the effective thread length for the first test configuration. Agreement between model and test results was found on a conservative basis. As outlook, considerations of additional bending stresses as well as parameter optimisation are seen as prerequisites and next steps for further model improvement and practicality.

AB - Self-tapping screws are efficient and flexible fasteners, applicable for many types of connections. Investigations on axially loaded groups of screws pointed out, that small spacing between the screws lead to block shear failure mode. So far, block and plug shear failure mode are only analysed for laterally loaded fasteners. Corresponding models cannot be simple transferred to primary axially loaded screws, because of their load insertion continuously along the effective thread featuring a thread-fibre angle perpendicular or with an angle to grain. Results gained by means of two different test configurations, with constant 90° thread-fibre angle but different configurations of group of screws and support conditions are presented. A block shear model is presented, and for mean values for stiffness and strength properties as model parameters are discussed together with values for parameters related to the force distribution over the effective thread length for the first test configuration. Agreement between model and test results was found on a conservative basis. As outlook, considerations of additional bending stresses as well as parameter optimisation are seen as prerequisites and next steps for further model improvement and practicality.

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