I have conducted a simple FEM analysis on this, though without knowing which loads are applied on the beam. If we take a 1500mm 80x40x5 VKR pipe and a force in the middle of the beam of 15000 N, I get a deflection of 1.7mm at worst.
If I calculate with 600kg (5883 N) as justusandersson mentions above, the deflection is 0.6mm.
These calculations do not account for the existing wall/beam and should probably be taken with a grain of salt. Additionally, I have only set "steel" as the material with the properties below:
Material Name Steel
Mass Density 7833,000 kg/m^3
Young's Modulus 199947,953 MegaPa
Poisson's Ratio 0.29
Thermal Expansion Coefficient 0.0000 /K
Thermal Conductivity 32.000 W/m-C
Yield Strength 262.001 MegaPa
Ultimate Strength 358.527 MegaPa
Great images and excellent method! A load greater than about 6kN doesn't need to be considered. 1/300 of a span of 1.4 meters is about 0.5 mm, so 0.6 can be considered OK. Especially if the floor joist representing the point load is rigidly spliced over the wall beam, as it would then have an upward internal bending moment.
Here's how it turned out, there will be another support to the left of the opening but the electrician needs to do some wiring first. Then construction plywood + plasterboard will be added.
