The first step is to model the structure’s mechanical skeleton, including its foundations, columns, beams, frames, trusses, and other elements. The start point is the architectural model. An architectural model shows what the structure will look like in reality, but it is not suitable for calculations due to the high level of detailing. The architectural model needs to be stripped until only the load-bearing structure remains. The load-bearing structure will transfer the applied loads to the ground.

Translating the load-bearing structure to a model ready for calculations is called schematization or creating the wireframe model, the mechanical model, or the plan of the model.

Schematization is a very important step: it is essential that that the mechanical model can anticipate loads since it would be the basis for the whole process.

The most used structural elements which can be included in the structural model are:

● Beams;

● Columns;

● Struts and ties;

● Slabs;

● Shear walls;

● Membranes.

Furthermore, modelling involves determining the structure’s material, whether it would be “structural steel”, “reinforced or prestressed concrete”, “timber”, or any material. The choice depends mostly upon the economy and safety of a structure. A lot of structure consists of both steel, concrete, and timber elements.

Modelling also involves assuming dimensions for each element which is the basis for self-weight computation for the load analysis. Estimating the member size includes what should be the element width, the depth or the thickness. Rules of thumb can be used for the choice of the initial dimensions.

Another relevant aspect in the modelling consists of defining the internal and external boundary conditions of the members that make up the structure.

Next, the structural engineer must identify all possible loads that the structure may experience during its lifetime. Examples of loads on structures are:

● Dead loads, meaning the self-weight of the structure

● Live loads: occupancy of people in buildings, moving equipment, and the movement of cars on bridges;

● Wind loads: any horizontal, uplift or shear pressures or forces that the wind exerts on a building;

● Snow loads: only applicable for structures expected to receive snowfall;

● Earthquake loads: when the structure is in a seismic region;

● Earth pressure: to be applied for tunnels, retaining walls, cellars;

● Water and ice: for some structures such as bridges, offshore platforms, and coastal structures;

● Thermal loads: Unequal heating or cooling of parts of the structure create high stresses;

● Dynamic loads: for example, induced by machinery.

So, depending on where your structure is, you must consider the various kinds of loads. The values of these loads can be identified using appropriate structural design codes and references.

In real life, different loads act simultaneously with the structure. The combination of the various loads should be evaluated. For instance, a simultaneous action between dead load (weight of the structure) and live load (use of the building by people) can be a load combination. But also, dead loads and wind loads can be a combination. Finding which is the worst load combination for your structure is a part of the loads analysis process. Usually, structural engineering software will automatically create a set with all possible loads combinations.

In this step, we perform the analysis on the structural members. The goal is to investigate how the structural model behaves with the different load combinations made. The analysis of a whole structure is also known as the global analysis.

The results of the analysis include the internal forces diagrams (shear, bending moment, normal, torsion and stresses), reactions, deformations/ deflections produced by the different load combinations.