Hi friends,

In the first #2 episodes of the engineering mechanics series, we talked about the different static systems and which of these are statically determinate/indeterminate. Today, we’ll look at the different types of loads that we apply to these static systems/beams.

Before we get started, we need to clarify the term “load”. In general, we differentiate between characteristic loads calculated according to Codes (like Eurocode) and, as I call them, geometrical loads which are basically the visual representation of the characteristic loads.

The latter is getting introduced in the very beginning of a civil engineering or architecture study, but at that time I personally didn’t know that these loads represent actual loads like the dead load. Also, because the calculation of characteristic loads is often taught in later semesters when you have your first design classes.

In this post, we’ll focus on the different types of geometrical loads.

Uniformly distributed line load (UDL)

Uniformly distributed line loads are probably the loads we use the most in structural engineering. They have the same load value over a certain distance. In the example below 3.0 kN/m are distributed over the length of the beam.

Examples where we use the UDL are:

• A beam supports a concrete slab. Then the dead load of the slab is transferred to the beam and applied as a UDL on the beam
• The wind load on a facade column. The wind loads are resisted by the facade elements, transferred to the column and applied as UDL on the column.

Point load

Point loads are also used a lot in structural engineering. Point loads have the unit Kilonewton [kN].

Examples:

• A point load could be a column supported by a beam (transfer structure)
• A beam supported by another beam.
• A beam supported by a column. Then the reaction force of the beam can be applied as a point load to the column.

Triangular load

Triangular loads have different load values of a certain distance of the structural element and on one side the value is 0. The unit is Kilonewton per meter [kN/m].

An example is:

• Hydrostatic pressure (water) on a retaining wall

Trapezoidal load

Trapezoidal loads have different load values of a certain distance of the structural element. The unit is Kilonewton per meter [kN/m].

An example is:

• Earth pressure on a retaining wall

Moment

Moments can also be added to static systems/beams. The unit is Kilonewton meter [kNm].

Area load

The characteristic loads for snow, wind, live, dead, earthquake, etc. are mostly given as area loads and applied to slabs and walls. These slabs and walls are then supported by other structural members and therefore transferred to line load, point load, etc. So, we usually start with area loads. The unit is Kilonewton per square meter [kN/m2].

As already said, examples are

• Dead, live, wind and snow loads on horizontal slabs and
• Wind loads on facade elements

Conclusion

Now we learned about the different static systems and what loads can be applied to these static systems. Next time, we can start calculating. We’ll be looking at the different support types and how to calculate reaction forces of static systems based on the loads we covered today.

Hope to see you next Wednesday for the episode #5 of the Engineering Mechanics Series.

Have a great rest of the week.

Cheers,

Laurin.

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