Before starting a steel beam calculation, it is necessary to collect the load acting on the steel beam. Depending on action duration, the load is divided into permanent and temporary.

Permanent loads include:

• own weight of the steel beam;
• own weight of the overlay, etc.;

Temporary loads include:

• long-term load (payload, taken depending on the building purpose);
• short-term load (snow load, taken depending on building geographical location);
• special load (seismic, explosive, etc. Not included in this calculator)

Loads on the beam are divided into two types: design and standard. Design loads are used to calculate the beam for strength and stability (limit state 1). Normative loads are established by the norms and are used to calculate the beam for deflection (limit state 2). Design loads are determined by multiplying the standard load by the reliability load factor. Within the framework of this calculator, the design load is applied when determining the beam deflection to the margin.

After we have collected the surface load on the overlay, measured in kg / m2, it is necessary to calculate how much of this surface load the beam takes on. To do this, it is necessary to multiply the surface load by beams step (the so-called cargo lane).

For example: We calculated that the total load was Qsurface = 500kg/m2, and the beams step was 2.5m. Then the distributed load on the steel beam will be: Qdistribution = 500kg/m2 * 2.5m = 1250kg/m. This load is entered into calculator

Next, the diagram of moments, transverse force is plotted. The plot depends on the beam loading scheme, the type of beam support. The plot is built according to the rules of structural mechanics. For the most commonly used loading and support schemes, there are ready-made tables with derived formulas for diagrams and deflections.

After plotting the diagrams, the strength (limit state 1) and deflection (limit state 2) are calculated. In order to select a beam for strength, it is necessary to find the required moment of inertia Wtr and select a suitable steel profile from the assortment table. For example, the maximum deflection fult=L/200 with a span L=6m means that the calculator will select the rolled profile section (I-beam, channel or two channels in a box) with maximum deflection not exceeding fult=6m/200=0.03m=30mm. To select a steel profile according to the deflection, the required moment of inertia Itr is found, which is obtained from the formula for finding the ultimate deflection. And also a suitable steel profile is selected from the assortment table.

From the two selection results (limit state 1 and 2), a steel profile with a large section number is selected.