Load carrying ability
Heavy-duty anchor Guidebook – Part 4
External influences – Load carrying abilityAll 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 stressIf 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 stressIf 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.
Types of loading
Static loadsThe 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 loadsThe 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