Beam Design (max allowable force) - Help

[its.me.lah]

Homework Statement

Case:

-Simply supported beam with central load. L = 570cm
- I-Beam. Height = 15cm. Base = 15cm. Thickness = 1cm.
- Material = mild steel. Assuming E = 210GPa.
- Safety Factor = 1.5.
- F = 2000N.

With those information i had obtained the I = 16.56x10^6 mm^4.

Now i don't know how to calculate:
- the max allowable force before it fails.
- If F = 2000N, is it safe to use this beam.

Please help.

 

[PhanthomJay]

You will need to find the maximum bending moment in the beam as a function of F, then find the maximum bending stress under that maximum moment, using the maximum bending stress formula, which you should be familiar with. Now you must know the yield stress for the given material, which must be given to you, since such yield stresses depend on the type of mild steel you are using. Apply safety factor appropriately, watch units, and solve for the allowable load F.

 

[its.me.lah]

Dear PhantomJay...i am totally lost with your solution...would you please explain further..

Actually this is not my homework..my company wants to design a gantry and they want me to calculate the maximum allowable force for the beam.

Thanx again..

 

[nvn]

You could assume tensile yield strength, Sty = 235 MPa. Then you could say the maximum allowable midspan point load is F = 21.0 kN.

By the way, its.me.lah, always leave a space between a numeric value and its following unit symbol. E.g., 2000 N, not 2000N. See the international standard for writing units (ISO 31-0).

 

[DeeNos]

I would first like to commend you for providing detailed information about the beam design. This level of detail is crucial in accurately determining the maximum allowable force and safety of the beam.

To calculate the maximum allowable force before failure, we need to consider the strength and stiffness of the beam. Mild steel has a yield strength of approximately 250 MPa, meaning it can withstand a maximum stress of 250 MPa before it starts to deform permanently. With a safety factor of 1.5, we can calculate the maximum allowable force as follows:

Max allowable force = (250 MPa / 1.5) x (16.56x10^6 mm^4 / 570 cm) = 253.8 kN

Therefore, the maximum allowable force before failure for this beam design is 253.8 kN.

To determine if the beam is safe to use with a central load of 2000N, we need to compare the applied load to the maximum allowable force. In this case, the applied load of 2000N is well below the maximum allowable force of 253.8 kN, indicating that the beam is safe to use.

In conclusion, with the given information and calculations, we can determine the maximum allowable force and confirm that the beam is safe to use for the given load. However, it is always important to double-check all calculations and consider any potential external factors that could affect the beam's performance in real-world conditions.