TRIANGULATED
COMPRESSION
ARTIFICIAL
TRACTION
NATURAL
FLEXURE
TORSION
FRAME
SHEAR
SHELL
A
O
A
D
I
Z
E
Q
S
H
E
A
R
C
U
C
O
M
P
R
E
S
S
I
O
N
I
V
Y
C
U
G
N
V
I
P
A
U
C
D
N
N
N
T
Y
M
U
Q
A
P
M
N
L
G
E
J
A
E
I
R
Z
S
T
X
L
V
E
E
H
T
L
T
U
H
B
I
N
A
D
E
C
M
W
M
A
X
U
W
O
Q
Y
O
O
O
R
A
U
E
I
L
Q
R
S
A
T
Q
I
C
S
R
O
O
C
X
U
I
A
J
R
Z
U
S
Y
F
Y
E
I
J
O
G
F
L
A
M
N
O
R
A
Y
L
F
O
D
S
N
B
C
U
A
I
P
O
B
X
I
E
J
F
Z
A
T
R
I
U
A
Q
T
U
T
W
A
X
W
G
I
Q
S
N
R
U
I
A
R
Y
N
Z
O
U
O
R
S
I
M
P
A
A
A
N
U
Q
E
D
N
R
T
K
K
I
I
F
R
C
J
A
T
V
A
A
K
E
A
T
M
F
T
