Entwicklung einer optimierten Schraubengeometrie für hochbeanspruchte Stahl‐Holz‐Verbindungen

Abstract

Development of an optimized screw geometry for highstressed steel-to-timber joints This paper deals with the geometrical optimization of mainly axially loaded self-tapping screws applied in steel-to-timber joints under tension parallel to grain. Focusing on steel failure, the head geometry and the zone before the thread were adapted. Consequently, differences to standard products were verified by laboratory tests on full-scale steel-to-timber joints and also by numerical modeling. A 2 to 8 % increase of load bearing resistance, a displacement of the location of screw failure deeper into the timber member as well as the development of a plastic hinge close to the head are the essential results of this study. Especially the yield deformation leads to a more homogenous load sharing between a group of screws, caused by an increased potential of ductility, and to an enhanced bearing behavior under long term as well as pulsating tensile loadings. In addition to that a proposal for the verification of the net crosssection of tensile joints with self-tapping screws is given.

Novel composite connection for timber–glass composite structures

“…To overcome this failure mode, a screw with an unthreaded zone near the screw head could be used to achieve higher loads. Through experiments using steel-to-timber connections with near-head modified screws, Ringhofer et al [31] showed that a 2-8% increase in the load-bearing resistance and a displacement of the location of the screw failure deeper into the timber member can be achieved. Meanwhile, the inclined shear screw showed only a small curvedness and could be simply unscrewed from the timber block.…”

System Connector “Double Dovetail Tenon”—A Wood–Wood Based Alternative for Connecting CLT-Elements

“…Schickhofer et.al. [7] also investigated experimental geometries of dovetail connections in tests and FE-simulations of bar combinations. Blaß and Enders-Comberg [8] experimented with measures to increase friction within the tenon contact by special shaping of the flanks of RDJ and they also showed the possibilities of multi-step load transfer paths within a stepped connection for truss nodes of timber constructions.…”