桁架内力计算的截面法
DESCRIPTION
ersfrfrTRANSCRIPT
-
1
3
FX = 0 FY = 0M = 0
-
2.
123
VA=VB HA=0
VA VB
-
3--,123
-
411N1N2N3K1
K1
MK1 = 0
N1
N1
K1
VA
-
522N2
MK2 = 0 , Y2
N2
K2
VA
X2
Y2
2
2N2
-
633N3
MK3 = 0 X3
N3
K3
VA
X3
Y3
3N3
-
7
KK
1KKMK=0
2K
-
81. abc
30kN90kN
-
9
-
10Na
Na
C
Mc0Na43080
Na = 60kN30kN
C
Na
-
11Nb
30kN
D
Nb
NbD
Nb E
MD0Yb12404 30120 Yb16.67 kN
EXb
Yb
2 2 16.67 23.57kNb bN Y= = =
-
12Nc
30kN
D Nc
NcE
Nc D
ME0Yc12 408 0 Yc 26.67kN
EXc
Yc
2 2 26.67 37.71kNc cN Y= = =
-
13. a.
m-ma
m m
Na
P P
-
14
Na
Na Xa Ya
FX=0
Xa= P
Na
NaYa
Xa
P
-
15
-
162. ab
3l
2l
-a
-
17a
Xa
FX=0 Xa= P P2Na =
-
18b
-b
-
19b
Xb
FX=0 Xb=2P P22Nb =
-
20
C
MC = 0 S
S
Y = 0
S
S=0
-
213 ab
3l
3l
VA=P VB=P
-
221
VA=P VB=P
1
Fy=0y1 = 0
01 =N
-
23a
0
-b.
O
0
0M0= 0
NaXa
Ya
3PYa =
P231Na =
-
24b-
b.
AMA=0 P32Yb =
P31N 5=b
0
A
0Nb
XbYb
-
25ab
-
26a
ACEFBD
= 0x Na=P
-
27b
= 0AM Xb
-
284
P27
P27
8d
2
-
295
P27 P
27
-5()
5
-
301
C
N5
P27
CMC=0
P42
123427
15 =
== PNN
-
313
P27 P
27
-3
5
-
323
C
CMC= 0
N3
Y3
X3
P21
3 =Y P221
3 =N
-
332
P27 P
27
-2()
5
-
342
P27
P21
Fy= 0
P22 =N
Y2
P=2Y
-
354
D,
D
PN4
D
Fy= 0P=4N
-
36 P78 3-16
I I
ab c
d
0
0
0
-
373-16 bd
I I
ab c
d
Fx0
0
GMG0
0N =dF
NdF
-
383-16 a
I I
ab c
00
0
d MF0
kN302
410210N =
+=aF
aFN
F
-
39 a
D
1 2
DKFy= 0
Y1Y2
D
Y2Y1
Y1Y2
N1=N2 =0
0 0
-
40I-IO
MO=0 6Na-203=0Na=10kN
00
I
I O
0
Na
-
415. 12
.
15kN 15kN
-
42
CMC0154N131020
1
15kN
N1
110 2 15 4
3
0CMN
h
= = N113.3kN
C
10kN
0CM
15kN
-
43
Y 0 15Y2100
2
15kN
Y2
5 kN2 2
23 2 5N 13
3 3+
= =
10kN
CD
2 10 15 5
0CD
Y
Q
= =
=
0CDQ
15kN