Shear hole embedment screw connection

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Sectional drawing of a typical screw connection.
It is unfavorable for a shear hole soffit screw connection that part of the thread comes into contact with the hole soffit of the sheet metal below when there is a load, whereby the tips of the thread turns are flattened. Either a screw with a longer shaft or a slide-proof, prestressed connection with a heavy-duty screw should preferably be used.

Shear hole soffit screw connection is a term used in steel construction that describes a connection by bolts , screws or rivets that are primarily loaded transversely to the axis of the shaft. As a result, the shaft is subjected to pressure and shearing and pressure is exerted on the reveal of the bore (hole reveal pressure ) of the interconnected components.

All simple screw and bolt connections are shear hole reveal connections, as far as

  1. the shank of the lanyard is loaded by transverse forces perpendicular to its axis and
  2. No special precautions are taken to provide screws or bolts with a defined preload in the longitudinal direction and at the same time to make the contact surfaces of the interconnected components non-slip so that occurring transverse forces do not load the connecting means, but are transmitted directly from component to component.

Shear hole reveal connections in steel construction

Rivets and bolts are the classic fasteners in steel construction. In the 1960s they were replaced by welded and screwed connections.

Simple screw connections with power transmission transversely to the direction of the screw axis are known today as shear hole soffit screw connection ( SV ) to express the difference to the pretensioned connection ( GV ), which can also be referred to as a friction connection.

In order to be able to insert the fasteners, the bores must be made slightly larger in diameter than the shaft of the associated screw or rivet. When the rivet is tightened, the shaft is compressed. It expands in diameter and completely fills the hole. In the case of screw connections, however, there is a certain amount of movement in the connection. As a result of this match play, a normal shear hole reveal screw connection exhibits slippage . It can therefore only be used to a limited extent for deformation-sensitive component connections such as dynamically stressed components in which the flexibility of the connections leads to a change in the load-bearing behavior.

In the case of fitting screws , the hole diameter should only be a maximum of 0.3 mm larger than the screw shaft . Shear hole embedment screw connections with fitting screws are abbreviated to SVP . Slidably preloaded connections with fitting screws are abbreviated as GVP .

Pre-tensioned screw connections with sliding resistance can be carried out with high-strength screws ( strength classes 8.8 and 10.9). The screws are tightened with a defined torque and the contact surfaces of the components to be connected are designed in such a way that sufficient friction or sliding resistance is achieved. The static friction achieved between the contact surfaces must be large enough that the components are not displaced against one another by the expected transverse forces. As a result, the compressive and shear stresses exerted on the shaft and hole reveal remain minimal and the shaft is essentially only subjected to tension.

Pre-tensioned screw connections, in which the contact surfaces (friction surfaces) between the components are not sufficiently resistant to sliding , are referred to as systematically pre-tensioned shear hole embedment screw connections and are abbreviated as SLV or with fitting screws as SLVP .

Shear hole embedment screw connections can fail due to:

  • Shearing of the screws,
  • Tearing open the hole,
  • Squeezing the edges of the holes to such an extent that the function and shape of the construction are damaged by the yielding of the connection .

Calculation of SL connections

According to Eurocode 3 , verifications of the base material, both gross and net cross-sections, and verification of the connection with regard to shearing and embedding must be carried out for shear hole embedment connections.

See also

Footnotes

  1. ↑ a b c d e Ulrich Krüger: Steel construction, part 1 , p. 56f, Verlag John Wiley & Sons, February 19, 2008