49 V I . BATANB LENTUR 1. MENURUT A I T C 1985 1 . 1 . A n a l i s a P e r h i t u n q a n 1 . 1 . 1 . T e g a n g a n L e n t u r ( B e n d i n g S t r e s s ) . B e s a r n y a t e g a n g a n l e n t u r y a n g t e r j a d i d i h i t u n g d e n g a n p e r u m us a n : ■fb = M/S < = F b ' < 6 - 1 ) Dimana : ■fb : T e g a n g a n l e n t u r y a n g t e r j a d i M : Momen l e n t u r y a n g b e k e r j a , d i h i t u n g d e n g a n a n a l i 5 a s t r u k t u r S : Momen k e t a h a n a n (Momen r e s i s t a n c e ) F b ’ : T e g a n g a n l e n t u r r e n c a n a y a n g b e s a r n y a d i b a h a s p a d a p a s a l 1 . 5 Untuk b a l o k p e r s e g i b e s a r n y a t e g a n g a n l e n t u r y a n g t e r j a d i a d a l a h : f b = 6 M / ( b d'-=) < 6 - 2 ) b : l e b a r penampang d : t i n g g i penampang 1 . 1 . 2 . L e n d u t a n ( D e f l e c t i o n ) .
50 B e s a r n y a l e n d u t a n y a n g t e r j a d i ' <6, ) d i h i t u n g d e n g a n a n a l i s a s t r u k t u r . S e d a n g l e n d u t a n maximum ( < ^ m a x ) y a n g d i i j i n k a n t e r g a n t u n g p e n g g u n a a n k o n s t r u k s i dan j e n i s b e b a n , s e s u a i d e n g a n t a b e i V I . 1 d a n t a b e l V I . 2. l a b e l V I . 1
Recommended
Def
j.oction
Limitations
A p p l i e d A p p l i e d L o a d + U s e C la s s ific a t io n L o a d O n l y D e a d L o a d R o o f b e a m s In d u s t r ia l 1/180 1 / 1 2 0 C o m m e r i c a l a n d in s tit u t io n a l W it h o u t p la s t e r c e ilin g 1/240 1/180 W i t h p la s t e r c e ilin g 1/360 1/240 F lo o r b e a m s O r d i n a r y u s a g e " 1/360 1/240 H i g h w a y b r i d g e s t r in g e r s 1/200 to 1/300 R a ilw a y b r i d g e s t r in g e r s 1/300 t o 1/400
"O rd in a ry usage classification for floors is intended for construction in which w alk ing com fort and m in im ized piaster cra ck in g are the m ain considerations. T h e s e recom m en ded deflection lim its may not elim inate all objections to vib rations such as in lon g spans a p p roa ch in g the m axim u m lim its or for some office and institutional applications w here increased floor stiflfness is desired. ^
Tabel VI.2
b : U ' n ■ ■ I ’ - . l t t i o n .; ' f f . -1} ■; — D c o i j I n c r '0 - K : e d : - G d A p p l i e d A p p l i e d L o a d + U s e C la s s ific a tio n L o a d O n l y K ( D e a d L o a d ) " F lo o r B e a m s C o m m e r c ia l, O f f i c e a n d I n s t it u t io n a l F lo o r jo is t s , sp a n s t o 26 ft* L L ^ 60 p s f 1/480 1/360 60 p s f < L L < 80 p s f 1/480 1/360 L L ^ 8 0 p s f 1/420 1/300 G ir d e r s , sp a n s to 36 ft° L L ^ 60 p s f 1/480' 1/360 60 p s f < L L < 80 p s f 1/420' 1/300 L L ^ 8 0 p s f 1/360' 1/240" K = I except for seasoned m em bers w here K = 0.5. Seasoned m em b ers for this usage are defined as having a m oisture content o f less than 16% at the tim e o f installation.
^For g ird er spans grea te r than 36 ft and joist spans grea te r than 26 ft, special design considerations may be required such as m ore restrictive deflection lim its and vib ration considerations that include the total mass o f the floor.
51 1 . 1 . 3 . T e g a n g a n G e s e r S e j a j a r S e r a t ( H o r i z o n t a l S h e a r ) . T e g a n g a n g e s e r s e j a j a r s e r a t ( h o r i z o n t a l s t r e s s ) d i h i t u n g d e n g a n p e r u m u s a n : = (V Q) / ( b I ) < = F v ' ( 6 - 3 ) Dimana f v Q b I V Fv ' T e g a n g a n g e s e r s e j a j a r s e r a t y a n g t e r j a d i Momen s t a t i s L e b a r b a l o k Momen i n e r s i a G a y a g e s e r v e r t i c a l T e g a n g a n g e s e r s e j a j a r r e n c a n a F v ' = Fv ( Co Cr^ C t ) ( 6 - 4 ) Untu k penampang p e r s e g i b e s a r n y a g a y a 1 i n t a n g y a n g t e r j a d i a d a l a h : f v = 1 , 5 V/ bd ( 6 - 5 ) B e s a r n y a g a y a g e s e r v e r t i k a l ( V ) d i t e n t u k a n d e n g a n b a t a s a n s e b a g a i b e r i k u t ; li. --- 1 * a -////^ '' A t -Gambar 6 . 1 K o n d i s i Be b a n Untu k G ay a L i n t a n g U ntuk b e b a n t e r b a g i r a t a p a d a j a r a k - d ( t i n g g i b a l o k ) d a r i p e r l e t a k a n b e s a r n y a b e b a n t e r b a g i r a t a d i a b a i k a n . ( l e = 1 - 2d ) U ntuk b e b a n b e r g e r a k p a d a p o s i s i b e b a n y an g m e n g h a s i l k a n V maximum b e s a r n y a g a y a y a n g t e r l e t a k p a d a j a r a k d d i a b a i k a n .
1 - 1 . 4 . T e g a n g a n Te k an T e g a k L u r u s S e r a t P a d a Tumpuan. B e s a r n y a t e g a n g a n t e k a n t e g a k l u r u s s e r a t p a d a tumpuan d i h i t u n g d e n g a n p e r u m u s a n : t c = Rv / ( b . l t , ) < = F c ' < 6 - 6 ) d i m a n a : ■fc : T e g a n g a n t e k a n t e g a k l u r u s s e r a t y a n g t e r j a d i Rv : R e a k s i v e r t i k a l p a d a tumpuan
It. : P a n j a n q penampang b a l o k y a n g menumpu ( l i h a t g b . 6 . 1 ) b : L e b a r penampang b a l o k y a n g menumpu Fci. : T e g a n g a n t e k a n t e g a k l u r u s s e r a t r e n c a n a Fc v_ = Fc (Cm C„ Ct> i 6 - 7 ) Untu k l b < 6 i n c h , b e s a r n y a Fc_i. j u g a d i r e d u k s i d e n g a n p a n j a n g b a l o k y a n g menumpu s e b a g a i b e r i k u t : Cxt, - + 0 , 3 7 5 ) / l b ( 6 - 8 ) Cit,
adalah
i a k t o r r e d u k s i , b e s a r n y a f a k t o r i n i b i s a d i l i h a t p a d a d a f t a r d i b a w a h i n i . 52 '■ 'b 1 L 5 n i r (■■-. r ‘ V. ] , . - 7 1 J - . V- ’1 ■ ■ '7 " 1 1 , ' ! ^ ^ ' 1 j0 9 453 1 . 2 . L a t e r a l S u p p o r t <Penaha n A r a b L a t e r a l ) Untu k m e nc eg ah t e r j a d i n y a l a t e r a l b u c k l i n g <tekuk a r a h l a t e r a l ) p a d a b a t a n g t e r l e n t u r , p a d a i n t e r v a l t e r t e n t u d i p a s a n g l a t e r a l s u p p o r t . Un tu k b a l o k penampang p e r s e g i p e m a s a n g a n l a t e r a l s u p p o r t b i s a d i d e k a t i ( a p p r o x i m a t e ) b e r d a s a r k a n p e r b a n d i n g a n t i n g g i - l e b a r penampang b a l o k < d/ b ) s e s u a i d e n g a n t a b e l V I . 3. l a b e l V I . 3 A p p r o x i m a t e L a t e r a l S u p p o r t R u l e s f o r Sawn Beams D e p t h - B r e a d t h R a t i o " R u l e 2:1 o r less N o la t e r a l s u p p o r t is r e q u ir e d 3:1 to 4 ;1 T h e e n d s s h a ll b e h e ld in p o s it io n , as b y fu ll- d e p t h s o lid b lo c k in g , b r i d g i n g , h a n g e r s , n a ilin g o r b o lt in g to o t h e r f r a m i n g m e m b e r s , o r o t h e r a c c e p t a b le m e a n s 5 ' I O n e e d g e s h a ll b e h e ld in lin e fo r its e n t ir e le n g th 6:1 B r i d g i n g , fu ll- d e p t h s o lid b lo c k in g , o r cro s s b r a c in g s h a ll b e in s ta lle d a t in t e r v a ls n o t e x c e e d in g 8 ft u n less b o t h e d g e s a r e h e ld in l in e o r u n le s s th e c o m p r e s s io n e d g e o f th e m e m b e r is s u p p o r t e d t h r o u g h o u t its le n g t h t o p r e v e n t la t e r a l d is p la c e m e n t , as b y a d e q u a t e s h e a t h in g o r s u b f lo o r in g , a n d th e e n d s a t p o in ts o f b e a r i n g h a v e la t e r a l s u p p o r t to p r e v e n t r o t a t io n 7:1 B o t h e d g e s sh a ll b e h e ld in l in e fo r t h e ir e n t ir e le n g t h “ Based on nom inal dim ensions. I f a b en d in g m em b e r is subject to both flexure and compression parallel to gra in , the d e p th -b re a ih ratio m ay be as much as 5:1 i f one ed ge is held firm ly in line. I f u nder all com bination s o f load the u nbraced ed ge o f the m em b e r is in tension, the ratio for the beam m ay be 6:1.
54 1 . 3 . F a k t o r K e l a n q s i n q a n ( S l e n d e r n e s s F a c t o r ) : C s B e s a r n y a - f a k t o r k e l a n g s i n g a n a d a l a h : C s = l e . d / b = < 6 - 9 ) Dimana d ; T i n g g i penampang b a l o k p e r s e g i b : L e b a r penampang b a l o k l e : P a n j a n g e f f e k t i - f b a l o k y a n g b e s a r n y a b i s a d i l i h a t p a d a t a b e l V I . 4 a t a u g am b a r 6 . 4 . T a b e l V I , 4 T y p e o f B e a m F ig u r e 5.14- N a t u r e o f L o a d K i n d o f L a t e r a l S u p p o r t a n d U n s u p p o r t e d L e n g t h s * V a lu e o f E f fe c t iv e L e n g t h { l , y S im p le b e a m U n i f o r m l y d is t r ib u t e d lo a d L o a d c o n c e n t r a t e d at c e n t e r E q u a l- e n d m o m e n t s A n y c o n c e n t r a t e d lo a d s a n d s p a c in g L o a d c o n c e n t r a t e d at c e n t e r T w o e q u a l c o n c e n t r a t e d lo a d s at \ p o in ts T h r e e e q u a l c o n c e n t r a t e d lo a d s at ^ p o in ts F o u r e q u a l c o n c e n t r a t e d lo a d s at 5 p o in ts F iv e e q u a l c o n c e n t r a t e d lo a d s at I p o in ts S ix e q u a l c o n c e n t r a t e d lo a d s at 7 p o in ts I I I I I I I I I I I I I 1.92 1.61. /„ 1.84/,,
1.92
1.11 1.68/„ 1 .5 4 /, 1.68 1.73 1.78L
k S e v e n o r m o r e e q u a l c o n c e n t r a t e d lo a d s e q u a lly s p a c e d I A n y lo a d in g C a n lile v e r b e a m m U n i f o r m l y d is t r ib u t e d lo a d n L o a d c o n c e n t r d t e d at u n s u p p o r t e d e n d 0 U n i f o r m l y d is t r ib u t e d lo a d w it h c o n c e n t r a t e d lo a d at u n s u p p o r t e d e n d p A n y lo a d in g I I I I I I I I 1.84 /„ 1 .9 2 /, 1.23 1.69 /„ 1.69 /„ 1.92 /„oambar
6,4
Uniform load
Ends held to prevent sideways movement or rotation. No . lateral support along top. / . = 1.92/„ No lateral support provided at concentrated load / . = 1.61/ \ No lateral support
J
along topL =
1.84/ Lateral support at load (typical)L= 1.921.
Ends held to prevent sideways movement or rotation. Lateral
support at load.
Ends held to prevent sideways movement or rotation. Lateral
support at load.
/, = 1.68/„
Ends held to prevent sideways movement or rotation. Lateral
support at load. /, = 1.54/„
Ends held to prevent sideways movement or rotation. Lateral
support at load. 4 Equal loads
i.= 1.68/„
Ends held to prevent sideways movement or rotation. Lateral
support at load. 5 Equal loads
Ends held to prevent sideways movement or rotation. Lateral support at load. 6 Equal loads 4=1-78/,
Ends held to prevent sideways movement or rotation. Lateral
support at load. 7 or more equal loads
4 = 1.84/, Any load— no lateral support except at ends L = 1.92/,, 54c L a te ra l s u p p o rt o n ly a t s u p p o rts
1 . 4 . U n s u p p o r t e d L e n g t h < P a n j a n q B e b a s B a l o k ) : l u B i l a m a n a b a g i a n t e r t e k a n b a l o k d i t a h a n s e l u r u h n y a s e p a n j a n g b a l o k , y a n g b e r t u j u a n u n t u k me nc ega h t e r j a d i n y a l a t e r a l d i s p l a c e m e n t dan p a d a u j u n g p e r l e t a k a n d i c e g a h t e r j a d i n y a l a t e r a l r o t a t i o n , maka b e s a r n y a u n s u p p o r t e d l e n g t h ( l u ) d a p a t d i a m b i l = 0 ^ D i s i n i b e s a r n y a p a n j a n g e - f - f e k t i f b a l o k < l e ) sama d e n g a n 0 j a d i ^ a k t o r k e l a n g s i n g a n ( s l e n d e r n e s s f a c t o r : C s ) sama d e n g a n 0 maka f a k t o r k s t a b i l a n a r a h l a t e r a l u n t u k b a l o k <Ci_) d e n g a n k o n d i s i t e r s e b u t a d a l a h sama d e n g a n 1. B i l a m a n a l a t e r a l s u p p o r t d i a d a k a n u n t u k mencegah t e r j a d i n y a l a t e r a l r o t a t i o n p a d a t i t i k - t i t i k u j u n g p e r l e t a k k a n t e t a p i t i d a k menc eg ah t e r j a d i n y a l a t e r a l d i s p l a c e m e n t a t a u l a t e r a l r o t a t i o n s e p a n j a n g b a l o k , maka b e s a r n y a u n s u p p o r t e d l e n g t h ( l u ) a d a l a h j a r a k a n t a r a t i t i k - t i t i k b e k e r j a n y a b e b a n t e r s e b u t . Untu k k o n d i s i s e p e r t i i n i b e s a r n y a p a n j a n g e f f e k t i - f b a l o k ( l e ) l i h a t g am b a r 6 . 4 , 1 . 5 . K o n t r o l L a t e r a l S t a b i 1 i t y P a d a b a l o k y a n g menahan momen l e n t u r h a r u s d i k o n t r o l k s t a b i l a n a r a h l a t e r a l s e s u a i d e n g a n k a t e g o r i b a l o k n y a , y a n g p e n e n t u a n n y a t e r g a n t u n g d a r i b e s a r n y a ^^aktor k e l a n g s i n g a n y a .
56 1 . 5 . 1 . B a l o k P e n d e k ( S h o r t Beam ) --- C s < = 10 P a d a b a l o k p e n d ek b e s a r n y a - f a k t o r k e s t a b i l a n a r a h l a t e r a l <Ci_) = 1, b e s a r n y a t e g a n g a n i e n t u r r e n c a n a a d a l a h : F b ' = Fb <Co Cm Cr Cf= Ci_ Cf C t ) < 6 - 1 0 ) Dimana : Fb : T e g a n g a n l e n t u r y a n g d i i j i n k a n Cd : F a k t o r 1amanya p embebanan Cm : F a k t o r k a d a r a i r Cf= : F a k t o r u k u r a n ( S i z e f a c t o r ) Cl. : F a k t o r k s t a b i l a n a r a h l a t e r a l b a l o k = 1 Cf, : F a k t o r k e t a h a n a n t e r h a d a p k e b a k a r a n Cf : F a k t o r b e n t u k ( Form f a c t o r ) Ct : F a k t o r t e ' m p e r a t u r P a d a k ond i s i no rma l (Cr>=CM=CF,=Ct=l) : F b - = Fb (C^^ C t ) ■; 6 - 1 1 ) 1 . 3 . 2 . B a l o k Menengah ( I n t e r m e d i a t e Beam) : 10 < Cs <= Ck P a d a b a l o k menengah b e s a r n y a f a k t o r k s t a b i l a n a r a h l a t e r a l ( Cl) a d a l a h : C l = C 1 - 1/3 ( C s / C k ) - " 1 ( 6 - 1 2 ) Ck a d a l a h f a k t o r un t u k b a l o k menengah ( f a c t o r f o r i n t e r m e d i a t e beam) y a n g b e s a r n y a u nt uk b a l o k p e r s e g i b e r p e n a m p a n g u t u h ( s o l i d s e c t i o n ) a d a l a h i Ck = 0 , 8 1 1 -i E ■ /Fb ' ' ■ ( 6 - 1 3 ) Dimana : E ' : M o d u l u s e l a s t i s i t a s y a n g d i m o d i f i k a s i E ' = E •; C„ Cf, Ct ) ( 6 - 1 4 ) F b ' ' = Fb ( C „ Cn Cf, C t ) ( 6 - 1 5 )
J a d i u n t u k k o n d i s i n o rm a l < E ' = E d a n F b ' ' = F b ) : Ck = 0 , 8 1 1 -J E/Fb { 6 - 1 6 ) B e s a r n y a t e g a n g a n l e n t u r re ncan ai u n t u k b a l o k menengah a d a l a h : Fb ’ = F b ' ' (Cf- C-f) u n t u k k o n d i s i n o r m a l F b ' = Fb (Ci= C f ) i 6 - 1 7 F b ' = F b ' ' . C i _ u n t u k k o n d i s i n o rm a l F b ' = Fb.Ci_ < 6 - 1 8 D a r i k e d u a p e r s a m a a n t e r s e b u t d i a m b i l y a n g t e r k e c i l . 1 . 5 . 3 . Ba l o k P a n j a n q ( L o n g Beam) : Ck < Cb < = 50 P a d a b a l o k p a n j a n g b e s a r n y a t e g a n g a n l e n t u r r e n c a n a t i d a k t e r g a n t u n g - f a k t o r Ci_, t e t a p i t e r g a n t u n g kemampuan b a h a n ( E ) dan f a k t o r k e l a n g s i n g a n < C s ) . Untu k penampang u t u h ( s o l i d s e c t i o n ) b e s a r n y a a d a l a h : F b ’ = 0 , 4 3 8 E ' / ( C s ) ' " < 6 - 1 9 ) P a d a k o n d i s i n o rm a l F b ' = 0 , 4 3 8 E/ ( C s ) ^ ( 6 - 2 0 ) 2. MENURUT PKKI 1961 2 . 1 . J a r a k B e n t a n g : 1 a . J a r a k b e n t a n g h a r u s d i a m b i l j a r a k a n t a r a k e du a t i t i k t e n g a h p e r l e t a k a n dan s e t i n q g i - t i n q i n y a a d a l a h : 1 , 0 5 >: j a r a k a n t a r a k e d u a uji.uig p e r l e t a k k a n , s e p e t i g am b a r 6 . 5 . 57 r’l /
id
58 P a n j a n g p e r l e t a k k a n d a r i s e b u a h b a l o k d i a t a s d u a p e r l e t a k k a n d i a m b i l s e t i n g g i - t i n g g i n y a 1/20 j a r a k a n t a r a k e d u a u j u n g p e r l e t a k a n <2bx < - 1/20 I d ) l i h a t g a m b a r 6 . 5 . b . Untu k p e r l e t a k k a n s e n d i s e b a g a i j a r a k b e n t a n g h a r u s d i a m b i l j a r a k a n t a r a k e d u a t i t i k s e n d i . c. J i k a s e b u a h b a l o k m e r u p a k a n b a l o k t e r u s a n < C D n t i n o u 5 b e a m ) , j a r a k b e n t a n g m a s i n g - m a s i n g l a p a n g a n d i a m b i l a n t a r a t i t i k - t i t i k t e n g a h m a s i n g -m a s i n g p e r l e t a k k a n (ga-mbar 6.6).
59 P a d a k o n d i s i s e p e r t i i n i m a s i n g - m a s i n g l a p a n g a n d a p a t d i a n g g a p s e p e r t i t e r l e t a k d i a t a s dua p e r l e t a k k a n , s e d a n g k a n t e g a n g a n l e n t u r y a n g d i p e r k e n a n k a n u n t u k b a l o k t e r s e b u t b o l e h d i n a i k k a n s e b e s a r 107.. d . P a d a b a l o k d e n g a n t u n j a n g ( g a m b a r 6 . 7 ) , s e b a g a i j a r a k b e n t a n g a d a l a h : 1 = + 1-^) / 2 ( 6 - 2 1 )
60 2 . 2 . L e n d u t a n Y a ng D i p e r k e n a n k a n Dengan m e n g a b a i k a n p e r g e s e r a n p a d a t e m p a t - t e m p a t s a m b u n g a n , l e n d u t a n p a d a s u a t u k o n s t r u k s i a k i b a t b e r a t s e n d i r i dan muatan t e t a p d i b a t a s i s e s u a i d e n g t a n t a b e l V I . 5. T a b e l V I . 5 . L e n d u t a n Maximum J e n i s K o n s t r u k s i L e n d u t a n maximum - B a l o k d e n g a n k o n s t r u k s i t e r l i n d u n g 1 /300 - B a l o k d e n g a n k o n t r u k s i t a k t e r l i n d u n g - B a l o k k o n s t r u k s i k u d a - k u d a s e p e r t i 1 /400 g o r d i n g , k a s a u d s b . 1/200 - K o n s t r u k s i r a n g k a b a t a n g t e r l i n d u n g 1/500 - K o n s t r u k s i r a n g k a b a t a n g t a k t e r l i n d u n g 1 /700 2 , 3 A n a l i s a P e r hi t u n q a n a . T e g a n g a n l e n t u r y a n g t e r j a d i a d a l a h : = M/Wn < = ■?,, u i 6 - 2 2 )
Dimana :
V i , -
: Teqap.gan lentur yang terjadi
M
; iiomen yang bekerja
Wn
: tiomen penahan netto
;
Tegangan
lentur
ijin
yang
di modi + i kasi
dengan
faktor beban <?) dan -faktor lingkungan
iB )
61
b . B e s a r n y a l e n d u t a n y a n g t e r j a d i ( f ) d i h i t u n g d e n g a n a n a l i 5a s t r u k t u r dan b e s a r n y a hal rus < = fma>: { T a b . V I . 5)
c . B e s a r n y a t e g a n g a n g e s e r a r a h h o r i z o n t a l ( s e j a j a r s e r a t ) a d a l a h : D
S
b
h
l „ = D S/ b l <=^// ( 6 - 2 4 ) Dimana : I/, : T e g a n g a n g e s e r s e j a j a r s e r a t y a n g t e r j a d iGaya 1 intang yang bekerja
Momen statis
Lebar balok
Tinggi balok
Tegangan geser ijin sejajar serat yang di modi-f i kasi
dengan
faktor beban ( O dan
taktor lingkungan <B)
Lintuk balok persegi
= 1,5 D/bd
(6-25)
d.
Besarnya tegangan tekan tegak li.irus serat yang
terjadi
pada t-Lunpuan adaiah ;
■Q-,
- Rv / b bl
(6-26)
Dimana :
<r..:- : Tegangan tekan tegak lurus serat yarig terjadi
; Tegangari geser ijin tegak lurus yang di modi-f i kasi
dengan faktor beban
k' ^ )dan -faktor lingkungan
(B)
b
: Lebar persampang ti.srnpuan
62
3 . PERBAIMDINGAN DAN DI SKUSI 1 - P e r b a n d i n q a n D a r i p e m b a h a s a n b a t a n g l e n t u r d a p a t d i a m b i l p e r b a n d i n g a n s e b a g a i b e r i k u t ; No, K r i t e r i a A I T C 19B5 PKKI 1961 B e b an - T e r p u s a t - M e r a t a D l l . P r a k i r a a n penampang p e r s e g i b j . s a n g k a r 1i n g k a r a n B e s a r n y a Ga y a L i n t a n g V P a n j a n g b e n t a n g e - f e k t i f u n t u k g a y a l i n t a n g : l e = l - 2 d P a n j a n g b e n t a n g e f e k t i f un t uk k o n t r o l 1 a t e r a l b u c k l i n g 1u= 0 1e = 0 1u >0 1e = . , 1 u L e = L t a k d i t i n j a u S I e n d e r n Cb 4 e d/b^- - S h o r t - I n t e r m e d i a t e -Long t a k d i t i n j a u F a k t o r - k e s t a b i 1 an a r a h l a t e r a l C, - S h o r t - I n t e r m e d i a t e -Long T e g . R e n c a n a T e g . i j i n di g a n d a k a n d q n . -f a k t o r - f a k t o r Fb ' = ----Fv ' = ___ F" C . ' m m m 8 _ e n d u t a n ia>: i mum t a k d i t i n j a u T e r g a n t u n g j e - nis. k o n s t r u k s i dan b e b a n n y a T e r g a n t u n g j e - n i s k o n s t r u k s i dan 1i n g k u n g a n n y a b e s a r a n y a n g d i
-t
i n j au F b < = F b ' F v < = F v ' Fc-i-<= Fc.!- Ama>: <r 11 < = , t w/ ^ - 5// <r I- ji-<. —<r t w; A ■f<= f max63 DI S KU S I H A SI L PERBANDINGAN - B e b a n d a n b e n t u k penampang p a d a k e d u a p e r a t u r a n t e r s e b u t b e b a s m e n g a m b i I n y a . - P e n e n t u a n g a y a 1 i n t a n g m e nu r ut A I T C d i t e n t u k a n o l e h p a n j a n g ef - f e k t i f n y a < l e ) l i h a t g a m b a r 6 . 1 s e d a n g menurut PKKI d i t e n t u k a n o l e h b e n t a n g i t u s e n d i r i . - A I T C m e n i n j a u l a t e r a l b u c k l i n g b e r d a s a r k a n s l e n d e r n e s s f a c t o r s e d a n g PKKI t i d a k m e n i n j a u l a t e r a l b u c k l i n g - - D a r i s l e n d e r n e s s f a k t o r A IT C membagi b a l o k m e n j a d i t i g a k a t e g o r i y a i t u s h o r t , i n t e r m e d i a t e dan l o n g y a n g d a r i k a t e g o r i b a l o k t e r s e b u t d i t e n t u k a n b e s a r n y a t e q a n g a n r e n c a n a , s e d a n g PKKI t i d a k membedakannya. S e l a n j u t n y a d a r i k o n s e p d a s a r p e r e n c a n a a n d a r i ke du a p e r a t u r a n t e r s e b u t d i b u a t p e r e n c a n a a n d a l am b e n t u k g r a f i k d e n q a n b e r p e d o m a n p a d a kayu mutu A dan d a l am k o n d i s i n o r m a l .
a. Moment Kriteria
Menurut AIJC
1985Hubungan Cs dan Fb :
-Short beam <Cs <=
1 0 ) :Fb' = Fb ‘Cv. C-f)
-Intermediate Beam
( 10< Cs <= Ck)
Fb' =Fb (C,_)
D i a m b i l y a n g t e r k e c i l Fb' = Fb (C,. C-f) Ck = 0,ail -J E/ Fb64 B e s a r n y a - f a k t o r Ck n o r m a l a d a l a h : t e r s e b u t b e r d a s a r k a n u n t u k k o nd i s i K l a s J a t i I I I I I I I V F a k t o r Ck 2 2 , 5 0 2 3 , 4 1 2 5 , 6 5 2 6 , 5 0 2 8 , 1 0 -L on g Beam (Ck < C s < = 5 0 ) F b ' = 0 , 4 3 8 E / ( C s = ) D a r i b a t a s a n t e r s e b u t d i g a m b a r k a n h u b u n g a n a n t a r a Cb dan Fb s e p e r t i g am ba r 6 . 9 . ' M e n u r u t PKKI 1961 PKKI t a k f n e n i n j a u l a t e r a l b u c k l i n g s e h i n g g a b e s a r n y a t e g a n g a n l e n t u r i j i n t i d a k d i p e n g a r u h i o l e h d i m e n s i penampang dan d ir nen s i p e n a mp a ng . A t a u b i s a d i k a t a k a n h u b u n g a n a n t a r a t e g a n g a n l e n t u r i j i n < ) d e n g a n f a k t o r k e l a n g s i n g a n b e r u p a g a r i s l u r u s s e p e r t i g am b a r 6 . 9 .
'oaftbai' 6,8, huhitnyart Cs rfencian ffe'
i£g.
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140. lae 128.k
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c s c (S H 80. 15 60. SO 40 20, j Katjit Ja t i 0 Kayu Kias I1 KaL4u Klas II
I Kayti Klas III
0 Kayu Kias IM
6 4 a
24
28
32
36
48
44
48 56
Faktor KelAngsirtQan_< Cs )
_______
GaRoaif' 6,9. Hwbungan ftnjka Keiarigsingan ■-
it
KftVU KELflS I
-mm
Jfill---KflVU KELfiS
II-KftVU KELA5 III
KfiVLI KEWS ly j 1 18 201 30 1 49 5( ftngka Kelansrsingan
65 b . D e f l e c t i o n C r i t e r i a M e n u r u t A ITC 1985 P a d a k e a d a a n b a t a s b e s a r n y a d e f l e c t i o n a d a l a h : ^ = (M K 1 = ) / E I = 1/N M = E l / a K N) { 6 - 2 7 ) S e d a n g b e s a r n y a t e g a n g a n l e n t u r maximum a d a l a h : F b ' = M d / 21 . M = 2 F b ' I / d ( 6 - 2 8 ) D a r i k e du a p e r s a m a a n < 6 - 27 d an 6 - 2 8 ) d i d a p a t : F b ’ = <E / 2NK) >: d/1 F b ' = d/1 < 6 - 2 9 ) mi = E/ 2NK D a r i p e r s a m a a n 6 - 2 9 t e r s e b u t d i d a p a t g r a - f i k h u b u n g a n Fb ' d e n g a n d/1 s e p e r t i g am ba r 6 . 1 0 . Dimana : li = liomen k e r j a E = M o d u l u s e l a s t i s i t a s I = Momen i n e r s i a 1 = P a n j a n g b e n t a n g K = Coef-f i c i ertt t h a t d e p e n s d e g r e e o f s u p p o r t f i x i t y Mi s a l u n t u k b e b a n t e r b a g i r a t a K= 5/ 48 dan u n tu k b e b a n t e r p u s a t d i t e n g a h b e n t a n g K= 1/12 ( k o n d i s i u j u n u g s e n d i —s e n d i ) N = C o e f f i c i e n t r e c o m e n d e d b y t h e d e s i g n c o d e M i s a l u n t u k b a l o k l a n t a i N =240 ( L i h a t t a b e l V I . 1 - V I . 2 ) MenyriAt PKKI 1961 P e r u m u s an d a s a r u n tu k d e f l e c t i o n c r i t e r i a m e nu r u t PKKI 1961
66 sama d e n g a n A I T C 1985 h a n y a b e r b e d a p a d a k o e t f i s i e n N j a d i g r a f i k p a d a g am ba r 6 . 1 0 d a p a t d i g u n a k a n u n t u k p e r e n c a n a a n b e r d a s a r k a n PKKI 1961, c . S h e a r K r i t e r i a H e n u r u t A I T C 1985 U nt u k b a l o k p e r s e g i p a d a k e a d a a n b a t a s b e s a r n y a t e g a n g a n l e n t u r r e n c a n a dan t e g a n g a n g e s e r r e n c a n a a d a l a h : F b - = 6M/bd= bd = 6 m / F b ' d ( 6 - 3 0 ) F v ' = l , 5 V / b d bd = l , 5 V / F v ' ( 6 - 3 1 ) D a r i k e d u a p e r s a m a a n ( 6 - 3 0 dan 6 - 3 1 ) t e r s e b u t d i d a p a t : 6 M / F b ' d = l , 5 V / F v ' F b ' = (6M F v ' / 1 , 5 V 1) >: ( 1 / d ) = ( 4 F v ' M / V I ) >: ( 1 / d ) Fb ' = >: 1 /d ( 6 - 3 1 ) m,. = 4 Fv ' M / ( V I ) D a r i p e r s a m a a n 6 - 3 1 t e r s e b u t d i g a m b a r k a n g r a f i k h u b u n g a n a n t a r a F b ' d e n g a n 1/d s e s u a i g a m b a r 6 . 1 1 . M e n u r u t P h ' ^ I 19^61 Perumusari d a s a r u n t u k s h e a r k r i t e r i a i n i a d a l a h sama d e n g a n A IT C 1985 h a n y a b e r b e d a p a d a p e n e n t u a n g a y a g e s e r j a d i g r a f i k p a d a gamba r 6 . 1 1 d a p a t d i g u n a k a n u n t u k p e r e n c a n a a n b e r d a s a r k a n PKKI 1961.
66.
6 6 b
taanbrtf Hubusigftii j'fc' ligriaan d'i
0 , 7 2 0 , 6 7
