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The reliability is high; the variation of the connection load-carrying capacity
is small, since the failure is connected to the formation of plastic
hinges in the steel dowels.
The performance of the connected wood composite is high. Based on
the net section (for 3 steel plates about 2/3 of the total section) the tensile
strength of Parallam (ft = 45 N/mm 2 ) has been reached. Therefore the performance
of the joint – based on the total section – reaches about 2/3.
The group effect is directly considered, since the test were made with
full size joints and corresponding high number of dowels (about 36 dowels)
or more than 200 shear planes per joint.
32-7-8 M U Pedersen, C O Clorius, L Damkilde, P Hoffmeyer, L
Eskildsen
Dowel type connections with slotted-in steel plates
Introduction
In the Eurocode the strength of dowel type connectors is determined according
to the theory of plasticity. When the loading is in the grain direction
the strength is well predicted by the plasticity theory. However, when
the loading is in the transverse direction splitting may supervene plastic
failure, as is shown in test series on smaller specimens with slotted-in steel
plates. The scope of the present investigation is to trace the effect of eccentric
transverse loading of full scale connections with slotted-in steel
plates primarily loaded in the grain direction.
Conclusion
In order to perform a better modelling of the results laid forward the authors
would like to state and discuss the following points:
1. Plastic failure criteria can successfully be applied for dominating axial
load and a 10% additional frictional load bearing capacity before final
splitting is obtainable.
2. Plastic failure criteria are less successful for dominating transverse load
and utilising 10% additional frictional load bearing capacity seems to
be optimistic.
3. The mechanical part of the plastic model may need refinement to include
eccentricity introduced in the slot in order to model plastic failure
accurately.
4. The material part of the plastic model may need refinement to include
strain hardening for fh,90. This may explain why the severest loaded
dowels in an eccentric loaded joint locally introduces splitting stresses
in excess of what is expected by a perfect plastic model.
5. Dowel holes have to be tight fitting when the failure mode utilises rotational
restraints of the outer part of the dowel.
6. No experimental evidence is found to substantiate the apparently sound
idea of increasing the non-plastic capacity by prescribing slender dowels.
CIB-W18 Timber Structures – A review of meeting 1-43 4 CONNECTIONS page 4.82