• Support PF! Buy your school textbooks, materials and every day products Here!

Beam Design

  • Thread starter mm391
  • Start date
  • #1
66
0
Hi,

Calculate the dimensions of a solid rectangular beam using the information below:

Max Bending Moment= 8280Nm

Ze = 36cm^3

Allowable Stress = 230MPa

d = 2b

Stress = moment/section modulus
 

Answers and Replies

  • #2
92
0
Where are your workings? Where is it you're having problems?
 
  • #3
66
0
Where are your workings? Where is it you're having problems?
Sorry I did this on my phone and I didn't have time to finish it.

I have the following:

230 = 8280/36cm^3 The problem I have is am not sure where or how to go about finding the dimensions from here.
 
Last edited:
  • #4
PhanthomJay
Science Advisor
Homework Helper
Gold Member
7,157
502
what's the section modulus formula for a rectangular beam?
 
  • #5
66
0
Z= I/y with y being depth/2.

But I can't see how this will help. Sorry.
 
  • #6
PhanthomJay
Science Advisor
Homework Helper
Gold Member
7,157
502
Z= I/y with y being depth/2.

But I can't see how this will help. Sorry.
Yes, Z= I/(d/2), so what is I in terms of the base (b) and height (d), for a rectangular cross section?
 
  • #7
66
0
Firstly thank you for your help and patience.

Yes, Z= I/(d/2), so what is I in terms of the base (b) and height (d), for a rectangular cross section?
((b*d^3)/(d/2) = b*d^2/6

Z = b*d^2/6

Z * 6 = b*d^2

But I still have two unknowns and one equation.
 
  • #8
PhanthomJay
Science Advisor
Homework Helper
Gold Member
7,157
502
Firstly thank you for your help and patience.



((b*d^3)/(d/2)
you mean (bd^3/12)/(d/2) = b*d^2/6
Z = b*d^2/6

Z * 6 = b*d^2

But I still have two unknowns and one equation.
No, you have 2 unknowns and 2 equations....the one that was given you....in your original post..

d = 2b
 

Related Threads on Beam Design

  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
9
Views
5K
  • Last Post
Replies
1
Views
537
Replies
3
Views
4K
Replies
3
Views
2K
Replies
0
Views
2K
Replies
1
Views
2K
Replies
2
Views
1K
Replies
10
Views
1K
Top