Stresses Due to Point Load 3 P P z = z 2 R 2 R - - PDF document

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Stresses Due to Point Load 3 P P z = z 2 R 2 R - - PDF document

Stresses Due to Point Load 3 P P z = z 2 R 2 R 3 2 P 3r z ( ) R = 1 2 + r 2 3 2 R R R z z R P ( ) R z =


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SLIDE 1

1

Wednesday, Sept. 5 CIVL 7166 1

Stresses Due to Point Load

z r R P

( ) ( )

⎡ ⎤ σ = ⎢ ⎥ π ⎣ ⎦ ⎡ ⎤ σ = − − υ ⎢ ⎥ π + ⎣ ⎦ ⎡ ⎤ σ = − υ − ⎢ ⎥ π + ⎣ ⎦

3 z 2 3 2 r 2 3 t 2

P z 2 R R P 3r z R 1 2 2 R R R z P R z 1 2 2 R R z R

Wednesday, Sept. 5 CIVL 7166 2

Stresses Due to Circular Load

q 2a z

( ) ( )

⎡ ⎤ ⎛ ⎞ ⎢ ⎥ σ = − ⎜ ⎟ ⎢ ⎥ + ⎝ ⎠ ⎣ ⎦ ⎡ ⎤ ⎛ ⎞ + υ ⎢ ⎥ σ = + υ − + ⎜ ⎟ ⎢ ⎥ + + ⎝ ⎠ ⎣ ⎦ ⎡ ⎤ ⎛ ⎞ + υ ⎢ ⎥ σ = + υ − + ⎜ ⎟ ⎢ ⎥ + + ⎝ ⎠ ⎣ ⎦

3 z 2 2 3 r 2 2 2 2 3 t 2 2 2 2

z q 1 a z 2 1 z q z 1 2 2 a z a z 2 1 z q z 1 2 2 a z a z

Wednesday, Sept. 5 CIVL 7166 3

Hooke’s Law

( ) ( ) ( )

⎡ ⎤ ε = σ − ν σ + σ ⎣ ⎦ ⎡ ⎤ ε = σ − ν σ + σ ⎣ ⎦ ⎡ ⎤ ε = σ − ν σ + σ ⎣ ⎦

z z r t r r z t t t r z

1 E 1 E 1 E

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SLIDE 2

2

Wednesday, Sept. 5 CIVL 7166 4

Strains Due to Circular Load

( ) ( ) ( ) ( ) ( )

⎡ ⎤ ⎛ ⎞ + υ υ ⎢ ⎥ ε = − υ + − ⎜ ⎟ ⎢ ⎥ + + ⎝ ⎠ ⎣ ⎦ ⎡ ⎤ ⎛ ⎞ + υ − υ ⎢ ⎥ ε = − υ − + ⎜ ⎟ ⎢ ⎥ + + ⎝ ⎠ ⎣ ⎦ ⎡ ⎤ ⎛ ⎞ + υ − υ ⎢ ⎥ ε = − υ − + ⎜ ⎟ ⎢ ⎥ + + ⎝ ⎠ ⎣ ⎦

3 z 2 2 2 2 3 r 2 2 2 2 3 t 2 2 2 2

q 1 2 z z 1 2 E a z a z q 1 2 1 z z 1 2 2E a z a z q 1 2 1 z z 1 2 2E a z a z

Wednesday, Sept. 5 CIVL 7166 5

Deflections Due to Circular Load

( )

( )

⎡ ⎤ + υ − υ = ε = + + − ⎢ ⎥ + ⎣ ⎦

2 2 z 2 2 z

qa 1 a 1 2 w dz a z z E a a z

( )

− υ =

2

  • 2qa 1

w E

Wednesday, Sept. 5 CIVL 7166 6

Rigid Loading

σ = −

z 2 2

qa 2 a r q 2a

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SLIDE 3

3

Wednesday, Sept. 5 CIVL 7166 7

Rigid vs. Flexible Loading

( )

− υ =

2

  • 2qa 1

w E Flexible Pl Flexible Plate ate

( )

π − υ =

2

  • qa 1

w 2E Rigid Plate Rigid Plate ( )

− υ =

2 flexible

  • rigid
  • qa 1

2 w E w

( )

− υ π

2

qa 1 2 E π = = ⇒ = = π

rigid

  • flexible
  • w

4 1.27 0.79 w 4

Wednesday, Sept. 5 CIVL 7166 8

Multiple Wheel Loads

( ) ( )

σ = σ + σ

L R A A L A R

r ,z r ,z

A

z rL rR

L R

Wednesday, Sept. 5 CIVL 7166 9

Ahlvin and Ulery (1962)

[ ] ( ) ( ) ( ) ( )

σ = + ⎡ ⎤ σ = υ + + − υ ⎣ ⎦ ⎡ ⎤ σ = υ − + − υ ⎣ ⎦ + υ ⎡ ⎤ = + − υ ⎢ ⎥ ⎣ ⎦

z r t

  • p

p 2 1 2 = function p 2 1 2 E = modulus pa 1 z w 1 E a A B A C F E A D E A H