( ) . .
, . . .
ebt es ( ) ,
ebt = es = . (5.1)
, (5.1)
(5.2)
a = Es / Eb , , a - , .. ;
.
= Rbtu, nt = 0,5. (5.2),
, (5.3)
, , 500 25 20,7 ; Eb 3040 . 10% 400, 500. 1525% .
. , ( 5 ) Ired, , .
, 0,4 .
, 0,4 250300 , 500590 ( ), 500, 600. ( ) 590 , .. 600, . , , , .
, . , , 0,3 0,4 ( 240-600).
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2. . , . .
(. 32, ) (. 32, ) , .
. 32. :
;
, :
- - ~ 2025 % ;
- - 7080 % ; 2-3 , .
(. 32, , 33). N t, lan (. 33, ).
tmax l an, t l an.
tm = N / (pdl an) (5.4)
2,54 ~7 . tm ..
(5.4) () , N (.. N = ssAs = sspd 2/4):
lan = N / (tmpd) = sspd 2 / (4 tmpd) = ssd / (4 tm). (5.5)
, ( ) (ss, d) (tm). lan ( ) , , .
2. . . ( ), (. 34).
. 34. :
; ( );
; ; ;
; ,
, , lan (. 34, .
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() , Rs ,
(5.6)
As us - , ;
Rbond - ,
Rbond = η 1 η 2 Rbt (5.7)
η 1- , , :
1,5 - ( 240);
2,0 - ( 500)
2,5 - ( A300, 400 500);
η 2 - , , :
1,0 - ds ≤ 32;
0,9 - 36 40 .
, (5.8)
lo,an - , (5.1);
As,cal, As,ef - , ;
- , .
( ) , = 1,0, - = 0,75.
lan , , ..
(5.8), ( , , , ..).
3. . , ( , ). .
esh esh , s ebt (. 35)
ebt = esh - esh , s (5.9)
sbt = ebt = ebtnEb. (5.10)
, ..
sbtAb - ssAs = 0 sbtAb = ssAs ., (5.11)
sbt = ss = ssms ss = sbt / ms. (5.12)
ebt = sbt /nEb es = ss / Es = sbt / msEs; (5.13)
(5.9)
sbt = (5.14)
a = Es /Eb.
, / , . ms Rbt . ms, , (5.14).
. , ( , ). , , , . : , , 400 . , ; 400 .
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, , .
, . . , . e sh , s 15×10-5, at = 1×10-5 -1 15 .
, . () . , , .
, , . , , . , . . .
, .
:
-
Sy = 0 Þ N = sbcAbc + sscAs;(5.15)
-
esc = ebc = (5.16)
- (5.16)
= , (5.17)
(5.17) (5.15) m = As / Ab,
. (5.18)
= , .. , N = const n (.. ). , sb , ssc (5.15) .
, , , , . . , () () ( ) .
. () . , , , (.. l = const), ,
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. (5.19)
, ( ).
+50 .
60200 ~ 30%.
500600 . , 300 : ~ 300 , ~ 500. , , . , , . .
, .