Load carrying ability

An important part of our guide to heavy-duty anchoring are external influences, which in turn have a major impact on the safety of the construction and thus on the choice of fastening element. In this article we deal with external influences in the form of load carrying ability:
 

External influences – Load carrying ability

All forces that act on a component from the outside cause internal stresses in the component, which are called (mechanical) stresses. Depending on how heavy a load is and how rigid a component is, stresses lead to deformation.

A component is usually subject to several types of loading at the same time. If the resulting stresses exceed the limits of a component, such as the minimum yield strength (RP02) or the minimum tensile strength (Rm), permanent deformations or even fractures occur. Therefore, load limits are checked and documented as part of an approval.

The resulting types of stress differ depending on how the external forces act. When working with anchoring, we deal with the following:
 

Tensile/compressive stress

If a body is pulled apart or compressed, the load is distributed evenly over the entire cross-sectional area of the body. The area therefore plays the main role in the calculation of the tensile and compressive stress.
 

Tangential stress (shear)

Shear stress and tangential stress occur, for example, because materials behave differently with temperature fluctuations (thermal expansion). This creates tensions.

Torsion/bending stress

If components are rotated about their own axis (torsion) or loaded transversely to the axis with a force (bending), a multitude of tensions arise around the component centre, the so-called neutral fibre.
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Types of loading

Stresses are also differentiated according to their duration of exposure:
 

Static loads

The force comes consistently from a fixed direction. It is stationary, which means that the tension remains the same. Yield strength and tensile strength are the decisive parameters for static loads in order to limit the maximum load on a component. The impact of wind is also part of the static load, since it is classified as “predominantly static”.
 

Dynamic loads

The size and direction of the force vary and with it the stress. The dynamic load is supplemented in detail according to the duration of its occurrence:

The direction and magnitude of the force change ...

• regular: cyclical change
• irregular: pulsating load
• random: impact load

In order to determine the limits of the dynamic load, complex tests and calculations are necessary, such as to determine the seismic performance classes C1 or C2. Products that have been tested against seismicity are, for example, the BA-V Plus, BA-E Plus, LIEBIG® SUPERPLUS BLS through bolts.

All types of loads at a glance

Conclusion

If the safety of a component is to be determined, it must first be clear which forces act on the component in what form and what tensions arise from this. Subsequently, other influences, such as moisture or heat (fire), must be taken into account, as damage due to corrosion or high temperature fluctuations reduce the strength of the material. We will talk about this in subsequent articles.