Construction Materials Coursework: Stiffness Calculation Help

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SUMMARY

The discussion centers on calculating stiffness in beam bending problems for construction materials, specifically for simply supported beams with a central load. Stiffness is defined as force divided by deflection, but obtaining necessary data can be challenging in hypothetical scenarios. Key factors include the Young's modulus for steel and timber, which is essential for accurate calculations. Additionally, the mechanical properties of wood vary significantly by species and moisture content, necessitating careful selection of representative values for calculations.

PREREQUISITES
  • Understanding of beam bending mechanics
  • Knowledge of Young's modulus for steel and timber
  • Familiarity with orthotropic materials and their properties
  • Ability to interpret mechanical properties from engineering texts
NEXT STEPS
  • Research the calculation methods for simply supported beams under central loads
  • Study the mechanical properties of various wood species and their impact on stiffness
  • Explore the significance of moisture content in timber strength calculations
  • Review resources on beam stiffness calculations, including relevant engineering textbooks
USEFUL FOR

Students in construction materials courses, civil engineers, and professionals involved in structural analysis and design who require a deeper understanding of beam stiffness calculations.

Kieran Mclean
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Stuck on a question in my Construction Materials coursework. Not asking for anyone to solve it for me but would be grateful if someone could point me in the right direction:

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As far as i was aware, stiffness = force/deflection, data which is not obtainable in a hypothetical circumstance.
 
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Kieran Mclean said:
Stuck on a question in my Construction Materials coursework. Not asking for anyone to solve it for me but would be grateful if someone could point me in the right direction:

View attachment 94170

As far as i was aware, stiffness = force/deflection, data which is not obtainable in a hypothetical circumstance.
Do you know how to solve a beam bending problem for a beam that is simply supported with a load applied at the middle of the beam?
 
Chestermiller said:
Do you know how to solve a beam bending problem for a beam that is simply supported with a load applied at the middle of the beam?
Regarding stiffness,yes, I have already calculated the stiffness of the existing steel and timber beams for previous questions, using further data acquired from testing (max load, max deflection)
 
Kieran Mclean said:
Regarding stiffness,yes, I have already calculated the stiffness of the existing steel and timber beams for previous questions, using further data acquired from testing (max load, max deflection)
Are you saying that you need to know the Young's modulus for steel and timber to solve this problem, or is there something else that is missing? Of course Young's modulus for these materials is readily available on line or in your textbook.

Chet
 
Chestermiller said:
Are you saying that you need to know the Young's modulus for steel and timber to solve this problem, or is there something else that is missing? Of course Young's modulus for these materials is readily available on line or in your textbook.

Chet
To be sure, the mechanical properties of wood vary by species, moisture content, etc. Simply specifying that one of the beams is made of "timber" doesn't really help.
Wood is also an orthotropic material, unlike steel, and the manner in which the load is applied affects which strength properties should be used.

This article describes the mechanical properties of wood:

http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch04.pdf
 
SteamKing said:
To be sure, the mechanical properties of wood vary by species, moisture content, etc. Simply specifying that one of the beams is made of "timber" doesn't really help.
Wood is also an orthotropic material, unlike steel, and the manner in which the load is applied affects which strength properties should be used.

This article describes the mechanical properties of wood:

http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch04.pdf
Thanks SteamKing. I knew these things. But, if I were in the OP's situation, I would choose some very rough representative values of the properties to make the calculations (maybe as high a value as I could find for wood, and as low a value as I could fine for steel). I'm guessing that the stiffnesses are going to have to come out vastly different between the steel beam and the wooden beams.
 

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