Welding shear and normal stress calculations

[Polar Bear]

Hello,

Does anybody know how to compute shear and normal stresses which take place due to applied load?

My case is a simply supported beam (120x120x6.5 length: 4.2m) reinforced by a plate (20x120 length: 2m). Plate is welded on a top of a beam and external force (F=15 kN) is applied to the beam. Welding size is a=10mm. How to compute weld's shear and normal stresses?

Beam and plate material is S355.

Please, take a look at attached files.
Regards,

Sergey

 

[Achy47]

Hello Sergey,

To compute the shear and normal stresses in your case, you will need to use the equations for shear and normal stress in a beam.

First, you will need to calculate the bending moment at the location of the weld using the applied load and the beam's properties (length, width, and thickness). This can be done using the formula M = FL/4, where M is the bending moment, F is the applied load, and L is the length of the beam.

Next, you will need to calculate the shear force at the location of the weld. This can be done using the formula V = F/2, where V is the shear force and F is the applied load.

Once you have calculated the bending moment and shear force, you can use the equations for shear and normal stress in a beam to determine the stresses in the weld. The equation for shear stress is τ = VQ/Ib, where τ is the shear stress, V is the shear force, Q is the first moment of area, I is the second moment of area, and b is the width of the beam. The equation for normal stress is σ = My/I, where σ is the normal stress, M is the bending moment, y is the distance from the neutral axis, and I is the second moment of area.

To calculate the first moment of area, you will need to determine the centroid of the weld. This can be done by dividing the weld into smaller sections and calculating the centroid for each section, then taking the weighted average of the centroids to determine the overall centroid. Once you have the centroid, you can calculate the first moment of area using the formula Q = A(y-y_c), where A is the area of the weld, y is the distance from the neutral axis, and y_c is the distance from the centroid to the neutral axis.

Finally, plug in all the values into the equations for shear and normal stress to calculate the stresses in the weld. Make sure to use consistent units throughout the calculations.

I hope this helps! Please let me know if you have any further questions.