Steel angle beam working out the defection

In summary, Homework Equations require the Young's modulus and moment of inertia of the material. The Attempt at a Solution starts with finding the cross-sectional dimension of the angle section and the box section it is welded to. He then draws a dimensioned sketch of the situation. Next, he asks for help in finding the moment of inertia and Young's modulus. If those values are not provided, he suggests finding them from first principles. Finally, he posts back his findings.
  • #1
guuy18
4
0

Homework Statement



I have a steel angle (40 x 40 x 5mm) which is welded to box section either side it is 1000mm in lenght. It will have have load of 45kg on it (point load). I need to find the maximum deflection of this beam, which i think will come under a fixed-fixed type beam.

Homework Equations



i assume i need the young modulus of this material and the moment of inertia to be able to work this problem.

The Attempt at a Solution


I am lost in where i have to start with this, how do i find the moment of inertia(do i need to find the neatral axis?) and what is the bes method of finding the deflection out .

Any starting point would be useful this is a project for college where i am designing a storage device and this part will be holding a slider for the drawers, however for the drawers to function properly there needs to be minimum deflection. if i am wrong please say, this is all a learning curve for me.
 
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  • #2
You need to draw a dimensioned sketch of the cross-section, so that your question can be correctly understood.
 
  • #3
angle.jpg


a = 40mm
b= 40mm
c = 5mm

ignore rads
 
  • #4
How does this angle cross-section relate to the box section to which it is welded? How big is the box-section? As you haven't provided this information, do you consider that it is irrelevant? And how do you know that the ends of the beam are moment-fixed (if that is what you meant), Can you identify the point of application of the load on the section? When you ask about the deflection, do you mean the longitudinal deflection on a span of 1m or do you mean the deflection of the tip of the angle section relative to its vertical leg; or both?
 
  • #5
The angle section is welded to the box section by a slot being machined out of the steel angle so it can be slotted into the box section

Heres a crude drawing of how its attached to the box section :

angle drawing.png


The size of the box section is irrelevant but if this info is needed it will be 50 mm X 50mm x 4mm wall section.

I am not sure how to identify if they are moment fixed, what would suggest they are or not.

im after the longitudinal deflection on a span of 1m on the steel angle

The Slider is going to be bolted on the steel angle which is going to take a load of 45 kg distributed evenly along the slider.
 
  • #6
In post #1 you said the load was a point load. In #5 you say it is distributed evenly. My suggestion is that you mke a lower bound estimate of the deflection, assuming a UDL and a fixed-ended beam; and an upper bound estimate assuming pin-ends and a central point load. Then, if these bounds are too far apart, you can do additional work to bring them closer. To get the deflection the easiest way is to find a formula in a book such as steel designers manual or similar. To get the moment of inertia, tables are published by the steel people who make the angle. If you want to do it from first principles, you will first need to find the centroid of the section, and then its second moment of area.
 
  • #7
ok thxs for the quick reply i will do what you suggested and i will post back my finding cheers .

And many thxs for the help.
 

1. What is the purpose of calculating the defection of a steel angle beam?

The defection of a steel angle beam is an important factor in determining the structural integrity and safety of a building or structure. It helps engineers and architects ensure that the beam can withstand the expected load and will not bend or break under stress.

2. How is the defection of a steel angle beam calculated?

The defection of a steel angle beam can be calculated using a mathematical formula that takes into account the beam's dimensions, material properties, and the applied load. This can be done manually or with the use of specialized software.

3. What factors can affect the defection of a steel angle beam?

The defection of a steel angle beam can be affected by various factors such as the type and quality of the steel used, the size and shape of the beam, the method of installation, and the magnitude and direction of the applied load. Temperature changes, corrosion, and external forces can also impact the defection of a beam.

4. How can the defection of a steel angle beam be reduced?

To reduce the defection of a steel angle beam, engineers can adjust the dimensions and shape of the beam, use higher quality steel, or add additional support such as braces or columns. Proper installation, maintenance, and regular inspections can also help prevent excessive defection.

5. What is considered an acceptable defection for a steel angle beam?

The acceptable defection for a steel angle beam depends on the specific application and building codes. Generally, a defection of less than 1/360th of the beam's span is considered acceptable for most residential and commercial structures. However, for bridges and other structures that require higher strength and durability, a lower defection limit may be necessary.

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