Slope and Deflection of a Simply Supported Beam

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SUMMARY

The discussion focuses on determining Young's Modulus [E] and the second moment of inertia [I] for a custom-designed simply supported beam. The beam is 10m long with various loads, including a 90kN point load and a uniformly distributed load of 12kN/m. The user previously calculated E as 200x109N/m2 and I as 2.9x10-3cm4, but lost the notes detailing the calculations. The correct formula for I for a solid rectangular section is Ixx = bd3/12, and E values can be found in material property tables.

PREREQUISITES
  • Understanding of beam mechanics and loading conditions
  • Familiarity with Young's Modulus and the second moment of inertia
  • Knowledge of the bending equation: E/R = sigma/y = M/I
  • Ability to interpret material property tables for E values
NEXT STEPS
  • Research methods to experimentally determine Young's Modulus for various materials
  • Study the derivation and application of the bending equation in beam analysis
  • Explore tables of second moment of inertia for different beam cross-sections
  • Learn about the impact of load distribution on beam deflection and slope
USEFUL FOR

Engineering students, structural engineers, and anyone involved in beam design and analysis will benefit from this discussion.

MathsRetard09
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The title is fairly misleading but is within the subject.

I have drawn up a beam of my own as part of my classwork because what bothers me is how you would find Young's Modulus [E] and the second moment of inertia without being given them.

Every question I have looked at has given me the two values combined hence, EI.

The beam I have drawn is 10m long. From the LHE going right, 2m in is a 90kN point load, 3.5m in from LHE is a 8kN point load, from 2m in from LHE across by 3m is a UDL 12kN/m, and 7.5m in from LHE is a final point load of 10kN.

RL = 103,1kN and RR = 40.9kN

In order for me to find ymax at the mid-point of the beam I require an EI value which because it's a beam I made myself, I do not have.

What I have available that I think was relevant:

a sheet that shows me data for different types of beams, with D x B, Ixx and Zxx values.
The bending equation: E/R=sigma/y=M/I
Ixx=bd^3/12

I had a go at this over 6 weeks ago and I got my E and I values, however I've lost the notes that have the calculations on them.

The values I got were, E = 200x10^9N/m and I = 2.9...x10^-3cm^4


All I am asking here for is the route / method taken to find the E and I - not EI, but the two individual values for the beam described above.

I would use symbols to draw the beam here but it would look a mess, but then again:



RL = 103.1kN |_2m_| 90kN_1.5m_| 8kN_3m_| 12kN/m[UDL] _2.5m_| 10kN_2.5m_| RR = 40.9kN

|____|[][][]|[][][]______|______| (Looks similar to this)


So if you know how to do all this just imagine your given this beam mainly to find the slope and deflection - which I know how to do.

Unfortunately you need an EI value, to find that you need both E and I.

If you know the method please share it here because my mind is blank haha.
 
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MathsRetard09 said:
I have drawn up a beam of my own as part of my classwork because what bothers me is how you would find Young's Modulus [E] and the second moment of inertia without being given them.
...
Ixx=bd^3/12
...
The values I got were, E = 200x10^9N/m and I = 2.9...x10^-3cm^4


This is posted is in the wrong section, but anyway...

I depends on the geometry of the beam's cross section. Ixx=bd^3/12 is correct for a solid rectangular section.

E depends on the material. Basically you have to measure it, but the values for many materials have already been measured and tabulated. 200x10^9N/m^2 (note, m^2 not m) is a reasonable value for steel.

Google will find you tables of formulas for I for different shaped beams, and values of E for different materials.
 

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