THE LOAD OF AN ANCHORAGE
The load on an anchorage is characterized by a few factors:
- Size
- Direction
- Point of application
The direction of the force determines whether it is a tensile force, compressive force or shearing force. Tensile and compressive forces operate longitudinally on the anchorage, while shear forces work at right angles to the anchorage. These forces, which result from the construction, must be absorbed by the anchor. A combination of loads often arises, which leads to a similarly combined load on the anchorage. When forces occur at a certain distance from the surface of the building material, which results in a bending moment.
The calculation of the distribution of forces on a construction defines the load on a fastening. In further calculations, safety factors are included. The size of the safety factor is determined by the structural engineer on the basis of safety risks and safety guidelines. When selecting an anchor, these risks should be evaluated. European technical approvals and the American guidelines specify as a qualification for the use of constructional anchoring elements that the load is stationary or quasi-static. In practice, however, non-stationary or dynamic loads also occur, for example in crane construction, lift construction or machine construction. The fastening of elements subject to dynamic loads must be undertaken using specially tested anchors. A particular form of dynamic load, which arises as a result of a collision, earthquake or explosion, is shock load. Fastening elements suitable for use with shock load are fitted with an indication of this such approval.
1. Tension
2. Pressure
3. Shear
4. F = Oblique tension = The combination of axial tension and shear
5. F +bending moment = The combination of tension and shear at a distance "e"
6. V + bending moment = Shear at a distance "e"