# Calculate bending moment on cantilevered I beam

I am not an engineer, and the maths that I have seen on other forum posts is beyond me.

I am trying to calculate the load that can be supported by a cantilevered Ibeam.

The data is as follows:

Width: 120mm Height: 240mm Web: 6mm Flange: 9mm

The beam is cantilevered 4 meters with a static load of 100kg per meter.

• Which way is the load being applied? In the plane of the web/direction of the measuring tape/up and down in the photo? Or is is being applied in perpendicular to the web/measuring tape or left/right in the photo? The beam has different capacity depending on which way it is being loaded. Also note that bending capacity will also be depending on the characteristics of the steel (Fy=350 MPa)? Nov 22, 2022 at 20:41
• What is this exercise for OP ? Do you intend to use the beam as a corbel ? Or is this for something else entirely ? Also, what exactly do you mean when you say "What additional load would be required to bend the beam?" Is there a maximum deflection that you don't want to cross ? Or are you more concerned with preventing the beam from buckling/collapsing ? Nov 23, 2022 at 4:58

Pointing out the obvious but sometimes it's missed. If you have beams that cantilever 4m, move the cantilever as far along the beam as possible. It will make attachment way easier and if you counter the load it's even better.

• This doesn't answer the question.
– Fred
Dec 23, 2022 at 7:45
• No it does not but it points out what may likely be his next question . He wants to know if it will work for the form he has imagined and I've answered the function question he may not think to ask before he cuts it. Also I forget I'm talking to a group with varied level of experience so I presume everyone sees my comment is based on the question, mounting will effect how the beam deflection is expressed upon install. Dec 23, 2022 at 8:05

Let us express a load of 100 kg in kN, because we usually give bending moments in kNm

$$100 \text{kg} = \dfrac{100\times 9.81}{1000} \text{kN}=0.981 \text{kN}$$

Bending moment does not depend on the width, height, flange thickness or web thickness. It depends only on the applied load and the cantilevered length of the I-beam.

We do not understand your second question. But, we would like to state that a point load applied at the free end of the cantilever is capable of bending the beam.

• OP needs to know how to calculate the maximum bending moment, and the most important criteria to determine the load capacity of a beam with given sizes.
– r13
Nov 22, 2022 at 17:36
• @r13 You seem to have understood OP’s requirements better than I do. Therefore, you are in a better position to answer this question. I kindly request you to post an appropriate answer. That would help not only OP, but also me. If you want, I am ready to take down my answer.
– YNK
Nov 22, 2022 at 18:06
• Just to remind you what the OP really needs is - a professional engineer.
– r13
Nov 22, 2022 at 19:30
• The beam seems to be embedded in an unreinforced, not cast-in formwork plain concrete. And on the top side, the beam is too close to the edge of the concrete. An undue large moment could break the concrete and cause failure. -This beam seems to be an IPE240 which ideally could support approximately a P load of 700kg in addition to the 100kg distributed load. but that would require a correctly reinforced foundation calculated for the moment, shear, and torsion. As it is no load is safe! Nov 22, 2022 at 19:30
• @kamran was that weak axis bending or strong axis bending. OP did not state which way they wanted to bend the beam did they? Nov 22, 2022 at 20:37