The document discusses the process of determining the design moment for a square slab using yield line analysis. It outlines the relationship between internal energy, external energy, and various parameters such as moment, rotation, and average moved distance. The goal is to equate internal and external energies to derive the design moment.

1. L

L
W
Design moment ?
How to determine Design moment for
aSquare slab using Yield lineAnalysis?

2. L

L
/ 2
L / 2
L
/ 2


Internal Energy = External Energy
Internal Energy = Moment * rotation * length of projected yield line
External Energy =Area * Load * Average moved distance for each right half slab
W
/ 2


/ 2
L
/ 2
L

3. L

L
/ 2
L / 2
L
/ 2


W
/ 2


Internal Energy = Moment * rotation * length of projected yield line
?
?
/ 2


/ 2
L

2 / 2
tan
L
 

2 2 / 2
small angle, tan
L
For  



2 / 2
L
 

4
L
 

4
Internal Energy * )
(M * *2
L
L



Internal Energy 8M
 

4. L

L
/ 2
L / 2
L
/ 2


W
/ 2



External Energy =Area * Load * Average moved distance for each right half slab
2
External E [(0.5* * ) * ( ) * ( )]*4
3
nergy L
L W
 

Average moved distance for each triangle=
3

2
3
External Energy WL


5. L

L
/ 2
L / 2
L
/ 2


W
/ 2



Internal Energy = External Energy
2
8M
3
WL
 
 
2
24
M WL
