k ... Ek, , Ik ...
rkk=EkIk.rkk=EkIk. (28)
k
gkk=1rkk.gkk=1rkk. (29)
( ) k l ... Ek, k, Il, l ...
rkl=EkIl.rkl=EkIl. (30)
k l
gkl=1rkl.gkl=1rkl. (31)
. . 8 1, 2 3
r11=Dr2+r3, r22=Dr1+r3, r33=Dr1+r2,r11=Dr2+r3, r22=Dr1+r3, r33=Dr1+r2,
1 2, 2 3, 3 1
r12=r21=Dr3, r23=r32=Dr1, r13=r31=Dr2,r12=r21=Dr3, r23=r32=Dr1, r13=r31=Dr2,
D = r 1 r 2 + r 1 r 3 + r 2 r 3.
, , ,
Σ P = Σ P, Σ EI = Σ I 2 r (32)
Σ EI ; , ... E I , ( ... ...); Σ I 2 r ; , .
1. (. 9) a b, c d, d f, r 1 = 6 , r 2 = 5 . r 3 = 15 , r 4 = 30 , r 5 = 6 .
rab.
r 4 r 5 (14)
r45=r4⋅r5r4+r5=30⋅630+6=5 ;r45=r4⋅r5r4+r5=30⋅630+6=5 ;
r 2;
r' = r 2 + r 45 = 5 + 5 = 10 .
r 1, r' r 3
rab=r1+r′⋅r3r′+r3=6+10⋅1510+15=12 . rab=r1+r′⋅r3r′+r3=6+10⋅1510+15=12 .
rcd.
r 4 r 5 ; r 3
|
|
r′′=r3+r4⋅r5r4+r5=15+30⋅630+6=20 . r″=r3+r4⋅r5r4+r5=15+30⋅630+6=20 .
rcd r 2 r
rcd=r2⋅r′′r2+r′′=5⋅205+20=4 . rcd=r2⋅r″r2+r″=5⋅205+20=4 .
rdf.
d f : r 5, r 4 r 2 + r 3 (13)
1rdf=1r5+1r4+1r2+r3=16+130+120=14,1rdf=1r5+1r4+1r2+r3=16+130+120=14,
rdf. = 4 .
2. (. 10) a b k (0 ≤ k ≤ 10).
: k = 0 k = 1 rab = 0; k = 0,5 rab = 250 .
3. , . 11, , r 1 = r 2 = r 3 = r 4 = r 5 = 10 .
a b ?
.
r 3, r 4 r 5 ; r 1; , r 3, r 4, r 5 r 1,
r′=r1⋅(r3+r4+r5)r1+(r3+r4+r5)=10⋅3040=7,5 . r′=r1⋅(r3+r4+r5)r1+(r3+r4+r5)=10⋅3040=7,5 .
rab = r' + r 2 = 7,5 + 10 = 17,5 .
.
r 1 r 3 , r 4 r 5 (. 11, ).
rab=r1⋅r3r1+r3+r2=10⋅1020+10=15 . rab=r1⋅r3r1+r3+r2=10⋅1020+10=15 .
4. (. 12) a b, :
. mn np.
: 10 .
5. a b (. 13, ): r 1 = r 2 = r 3 = r 4 = r 5 = r 6 = r 7 = 10 .
. 13, .
rab=r1⋅r3r1+r3=(r5+r6+r4⋅r7r4+r7)⋅r2r5+r6+r4⋅r7r4+r7+r2=5+25⋅1035=12,1 . rab=r1⋅r3r1+r3=(r5+r6+r4⋅r7r4+r7)⋅r2r5+r6+r4⋅r7r4+r7+r2=5+25⋅1035=12,1 .
, . 13, .
r′=r1⋅r3r1+r310⋅1020=5 ,r′=r1⋅r3r1+r310⋅1020=5 ,
r'',
1r′′=1r4+1r7+1r2,1r″=1r4+1r7+1r2,
r' = 3,33 . ,
rab=r′+r′′=5+3,33=8,33 . rab=r′+r″=5+3,33=8,33 .