De 22

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phÇn 2 - bµI to¸n tÊm ph¼ng Sè hiÖu bµI tËp: 22

§Ò bµi sè 22 Cho kÕt cÊu chÞu lùc nh­ trªn h×nh 01. Trong ®ã: a = 3m, t = 10cm, E = 1.2x106 N/cm2, ν= 0.18, P = 20 kN, q = 5 kN/m. Yªu cÇu: - TÝnh chuyÓn vÞ c¸c nót, - X¸c ®Þnh vÐc t¬ øng suÊt trong c¸c phÇn tö.

H×nh 01 - S¬ ®è kÕt cÊu

phÇn tÝnh to¸n bµI 22 1. C¸c sè liÖu ban ®Çu . ChiÒu dÇy tÊm t = 0.10 m . KÝch th­íc cña kÕt cÊu a = 3.00 m . M« ®un ®µn håi E = 1.2E+07 kN/m2 . HÖ sè Po¸t - x«ng ν = 0.18 2. Chia kÕt cÊu thµnh c¸c phÇn tö vµ c¸c th«ng tin cho tÝnh to¸n

H×nh 02 - S¬ ®å rêi r¹c cÊu KÕt cÊu ®­îc chia thµnh 16 phÇn tö tam gi¸chãa nh­ kÕt h×nh 02. Liªn kÕt biªn d­íi cña tÊm ®­îc m« h×nh hãa bëi c¸c liªn kÕt gèi cè ®Þnh t¹i c¸c nót däc theo biªn nµy.

KÕt cÊu ®­îc chia thµnh 16 phÇn tö tam gi¸c nh­ h×nh 02. Liªn kÕt biªn d­íi cña tÊm ®­îc m« h×nh hãa bëi c¸c liªn kÕt gèi cè ®Þnh t¹i c¸c nót däc theo biªn nµy. C¸c th«ng tin vÒ nót: Sè hiÖu nót 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 To¹ ®é X 0 0 0 1.5 1.5 1.5 3 3 3 4.5 4.5### 6 6 6 To¹ ®é Y 0 1.5 3.0 0.0 1.5 3.0 0.0###3.0 0.0 1.5###0.0 1.5 3.0

TÝnh to¸n dêi t¶i träng ph©n bå vÒ c¸c nót

H×nh 03 - S¬ ®å chia t¶i träng vµ dêi t¶i träng vÒ nót C¸c th«ng tin vÒ t¶i träng: Sè hiÖu nót 1 2 3 4 Px 0 ? ? ? PY

?

0

0

?

5 0

6 0

7 ?

8 0

9 10 11 12 13 14 15 0 ? 0 0 ? ###-3.75

0

0

?

0

0

?

0

0

?

Sau khi xö lý ®iÒu kiÖn biªn ta cã vÐc t¬ chuyÓn vÞ cÇn t×m: ∆ = {'u2 v2 u14 v14

v3 u5 v5 u6 v6 u8 v8 u9 v9 u11 v11 u12 v12 u15 v15 }

0

-20

3. LËp ma trËn ®é cøng 3.1. LËp ma trËn ®é cøng phÇn tö Ma trËn ®é cøng cña phÇn tö ®­îc x¸c ®Þnh bëi c«ng thøc:

[

[ k ii ] [ k ij ] [ k im ] [ k ] = [ k ji ] [ k jj ] [ k jm ] [ k mi ] [ k mj ] [ k mm ]

]

Trong ®ã:

[

1−ν br bs cr c s Et 2 [ k rs ] =  4 1− ν 2  Δ νc b  1−ν b c r s r s 2  r=i , j , m ; s=i , j , m 

1−ν c r bs 2 1− ν cr c s br b s 2 νb r c s 

]

Hay ma trËn [k] cã thÓ viÕt l¹i nh­ sau:

[

1−ν c c 2 i i 1−ν νc i b i  bi ci 2 1−ν b j bi  c j ci Et 2 [ k ]= 2 4  1−ν  Δ νc b  1−ν b c j i j i 2 1−ν bm bi  c c 2 m i 1−ν νc m b i  bm ci 2 bi b i 

1−ν ci bi 2 1−ν c i ci  b i bi 2 1−ν νb j c i c j bi 2 1−ν c j ci  b j bi 2 1−ν νb m c i cm bi 2 1−ν c m ci  bm bi 2 νb i c i

1−ν c c 2 i j 1−ν νc i b j  bi c j 2 1−ν b j b j cjcj 2 1−ν νc j b j  bjcj 2 1−ν bm b j  c c 2 m j 1−ν νc m b j  bm c j 2 bi b j 

1− ν cib j 2 1−ν ci c j  bi b j 2 1− ν νb j c j  c jbj 2 1−ν c j c j bjbj 2 1− ν νb m c j  cm b j 2 1−ν cm c j  bm b j 2 νb i c j 

1− ν ci c m 2 1− ν νc i b m bi cm 2 1− ν b j b m c j cm 2 1− ν νc j b m b jcm 2 1− ν b m b m cm cm 2 1− ν νc m b m b m cm 2 b i b m

Ta ph©n c¸c phÇn tö tam gi¸c cña kÕt cÊu thµnh hai lo¹i: Lo¹i 1 gåm c¸c phÇn tö: 1,2,5,6,9,10,13,14 (h×nh 05) Lo¹i 2 gåm c¸c phÇn tö: 3,4,7,8,11,12,15,16 (h×nh 06) LËp ma trËn ®é cøng cña phÇn tö lo¹i 1 y m

i

Tªn nót To¹ ®é X To¹ ®é Y

j

x

H×nh 05 - PhÇn tö lo¹i 1

i 0 0

TÝnh c¸c hÖ sè: ai= xjym-xmyj = 2.3 bi = yj-ym = 0.0 ci = xm-xj = -1.5 aj = xmyi-xiym = 0.0 bj = ym-yi = 1.5 cj = xi-xm =0.0 am = xiyj-xjyi = 0.0 bm = yi-yj = -1.5 cm = xj-xi =1.5

DiÖn tÝch tam gi¸c ijm: 1

xi

yi

j 1.5 1.5

m 0 1.5

1−ν c b 2 i m 1−ν ci c i bi b m 2 1−ν νb j c m  c j bm 2 1− ν c j c m b j bm 2 1−ν νb m c m  c b 2 m m 1− ν c m c m b m bm 2 νb i c m 

]

∆ = 0.5*

∆ = 0.5*

1 1

xj xm

yj ym

1 1 1

0 1.5 0

0 1.5 1.5

=1.1

i 0 0

j 1.5 0

LËp ma trËn ®é cøng cña phÇn tö lo¹i 2 y

Tªn nót To¹ ®é X To¹ ®é Y

m

j i

x

H×nh 06 - PhÇn tö lo¹i 2

TÝnh c¸c hÖ sè: ai = xjym-xmyj = 2.3 bi = yj-ym =-1.5 ci = xm-xj =0.0 aj = xmyi-xiym = 0.0 bj = ym-yi = 1.5 cj = xi-xm = -1.5 am = xiyj-xjyi = 0.0 bm = yi-yj =0.0 cm = xj-xi =1.5

DiÖn tÝch tam gi¸c ijm:

∆ = 0.5*

1 1 1

0 1.5 1.5

0 0 1.5

=1.1

m 1.5 1.5

Ma trËn ®é cøng phÇn tö tam gi¸c lo¹i 1

(14) (13) (10) (9) (6) (5) (2) (1)

[k]1 =

u11

v11

0

u15 u14 u12 u11 u9 u8 u6 u5

v15 v14 v12 v11 v9 v8 v6 v5

u12 u11 u9 u8 u6 u5 u3 u2

v12 v11 v9 v8 v6 v5 v3 v2

0 u8

0 v8

0 u5

0 v5

0 u2

0 v2

0 254237

0

0

-254237

-254237

254237

0

620091

-111616

0

111616

-620091

0

-111616

620091

0

-620091

111616

-254237

0

0

254237

254237

-254237

-254237

111616

-620091

254237

874328

-365854

254237

-620091

111616

-254237

-365854

874328

0 0 u5 v5 u2 v2

u2 v2 u6 v6 u3 v3

0 0 u8 v8 u5 v5

u5 v5 u9 v9 u6 v6

0 0 u11 v11 u8 v8

u8 v8 u12 v12 u9 v9

0 0 u14 v14 u11 v11

u11 v11 u15 v15 u12 v12

(1)

(2)

(5)

(6)

(9)

(10)

(13)

(14)

Ma trËn ®é cøng phÇn tö tam gi¸c lo¹i 2 (16) (15) (12) (11) (8) (7) (4) (3)

[k]2 =

u11

v11

u14

v14

0

u15 u14 u12 u11 u9 u8 u6 u5

v15 v14 v12 v11 v9 v8 v6 v5

0 u8

0 v8

0 u11

0 v11

0 u5

0 v5

0 u8

0 v8

0 u2

0 v2

0 u5

0 v5

0

0

0

620091

0

-620091

111616

0

-111616

0

254237

254237

-254237

-254237

0

-620091

254237

874328

-365854

-254237

111616

111616

-254237

-365854

874328

254237

-620091

0

-254237

-254237

254237

254237

0

0 0 0 0 u5

u2 v2 u5 v5 u6

0 0 0 0 u8

u5 v5 u8 v8 u9

0 0 0 0 u11

u8 v8 u11 v11 u12

0 0 0 0 u14

u11 v11 u14 v14 u15

-111616

0

111616

-620091

0

620091

v5

v6

v8

v9

v11

v12

v14

v15

(3)

(4)

(7)

(8)

(11)

(12)

(15)

(16)

3.2.LËp ma trËn ®é cøng cña kÕt cÊu

u2

v2

u3

v3

u5

v5

u6

v6

u8

v8

u9

v9

u11

v11

u12

1240182

0

620091

-111616

0

0

0

-223233

0

0

0

-223233

0

0

0

0

508475

-254237

254237

0

0

-508475

0

0

0

-508475

0

0

0

-508475

620091

-254237

874328

-365854

0

0

254237

-111616

0

0

254237

-111616

0

0

254237

-111616

254237

-365854

874328

0

0

-254237

620091

0

0

-254237

620091

0

0

-254237

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

-508475

254237

-254237

0

0

508475

0

0

0

508475

0

0

0

508475

-223233

0

-111616

620091

0

0

0

1240182

0

0

0

1240182

0

-254237

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

-254237

0

0

508475

0

0

0

508475

0

0

0

508475

[K]=0

-508475

-223233

0

-111616

620091

0

0

0

1240182

0

0

0

1240182

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

-254237

0

0

0

0

0

0

0

-254237

0

0

508475

0

0

0

508475

0

0

0

508475

-111616

620091

0

0

0

1240182

0

0

0

0

0

0

0

0 -620091

111616

0

0

0

223233

0

0

0

223233

0

0

0

254237

-254237

0

0

508475

0

0

0

508475

0

0

0

508475

-620091

-254237 -620091

111616

0

0

254237

111616

0

0

254237

111616

0

0

254237

-111616

-254237 254237

-254237

0

0

254237

620091

0

0

254237

620091

0

0

254237

0 -223233 -1240182 0

0

0

-508475 254237 0 -508475

v12

u14

-223233 -1240182

v14 0

u15

v15

-620091 -111616

0

0

-508475 -254237 -254237

-111616

-620091

254237

-620091

254237

620091

111616

-254237

111616

-254237

0

0

0

0

0

0

0

0

0

0

0

0

508475

254237

254237

1240182

223233

0

111616

620091

0

0

0

0

0

0

0

0

0

0

0

0

508475

254237

254237

0

223233

0

111616

620091

0

0

0

0

0

u2 v2 u3 v3 u5 v5 u6 v6 u8 v8 u9 v9 u11

0

0

0

0

0

0

0

508475

254237

254237

1240182

223233

0

111616

620091

223233

1240182

0

620091

111616

0

0

508475

254237

254237

111616

620091

254237

874328

0

620091

111616

254237

0

874328

v11 u12 v12 u14 v14 u15 v15

4. LËp ph­¬ng tr×nh c©n b»ng 1240182

0

0

508475

620091 -111616

0

0

0

-223233

0

0

0

-223233

0

0

0

-223233

###

254237

0

0

-508475

0

0

0

-508475

0

0

0

###

0

0

620091 -254237 874328 -365854

0

0

254237

-111616

0

0

254237 -111616

0

0

-111616 254237

-254237 620091

0

0

###

620091

111616

###

###

874328

0

0

-254237

620091

0

0

254237 -111616 -620091

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

508475

0

0

0

508475

0

0

0

508475

0

0

0

-508475 254237 -254237

-223233

0

###

620091

0

0

0

1240182

0

0

0

###

0

-254237

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

-508475

0

-254237

0

0

508475

0

0

0

508475

0

0

0

508475

0

0

-223233

0

###

620091

0

0

0

1240182

0

0

0

###

0

0

0

0

223233

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

-254237

0

0

0

0

0

0

0

0

0

0

0

508475

0

0

0

508475

0

0

0

508475

0

0

0

-508475 254237 -254237

-223233

0

###

620091

0

0

0

1240182

0

0

0

0

0

0

0

###

0

###

111616

0

0

0

223233

0

0

0

223233

0

0

0

-508475 254237 -254237

0

0

508475

0

0

0

508475

0

0

0

508475

0

1240182 223233

1240182 223233 223233 1240182 0

0

-620091 -254237

###

111616

0

0

254237

111616

0

0

254237 111616

0

0

254237 111616

620091

-111616 -254237 254237 -254237

0

0

254237

620091

0

0

254237 620091

0

0

254237 620091

111616

5

6

7

8

9

10

11

12

13

14

15

5. C¸c chuyÓn vÞ nót tªn nót

1

2

3

4

u

0

###

###

0

### #VALUE!

0

###

###

0

###

###

0

###

###

v

0

###

###

0

### #VALUE!

0

###

###

0

###

###

0

###

###

###

###

u2

0

u2

#VALUE!

###

###

###

v2

0

v2

#VALUE!

254237

###

254237

u3

0

u3

#VALUE!

###

111616

###

v3

0

v3

#VALUE!

0

0

0

u5

0

u5

#VALUE!

0

0

0

v5

0

v5

#VALUE!

u6

0

u6

#VALUE!

v6

0

v6

#VALUE!

u8

0

u8

#VALUE!

0

v8

508475 254237 254237 0

111616 620091

0

0

0

0

0

0

508475 254237 254237 0

111616 620091

x

v8

=



0

=

#VALUE!

u9

0

u9

#VALUE!

v9

0

v9

#VALUE!

0

0

0

u11

0

u11

#VALUE!

0

0

0

v11

0

v11

#VALUE!

u12

0

u12

#VALUE!

508475 254237 254237 0

111616 620091

v12

0

v12

#VALUE!

0

620091 111616

u14

-7.5

u14

#VALUE!

508475 254237 254237

v14

0

v14

#VALUE!

254237 874328 254237

0

0

u15

-3.75

u15

#VALUE!

874328

v15

-20

v15

#VALUE!

6. X¸c ®Þnh c¸c vÐc t¬ øng suÊt trong c¸c phÇn tö VÐc t¬ øng suÊt trong c¸c phÇn tö ®­îc x¸c ®Þnh th«ng qua vÐc t¬ chuyÓn vÞ nót cña theo c«ng thøc sau:

{}

σx { σ } = σ y = [ D ][ B ] { δ }e τ xy e

[

1 0 [ D ] [ B ]= E 2 ν 0 1−ν 0 1− ν 2

0 0 1− ν 2

ν −1 1 −ν 1− ν 0 − 2

−ν −1 1−ν − 2

]

{}

ui vi u { δ }e = j vj um vm

[D][B]

=

### 2232327 0

0 0 ###

0 0 5084746

0 1 0

-1.00 -0.18 -0.41

-0.18 -1 -0.41

TÝnh cho phÇn tö thø nhÊt: 0.00E+00 0.00E+00 #VALUE!

σx {σ}

e

1

=

σy

=

τxy 1

[D][B] x

#VALUE! #VALUE! #VALUE!

#VALUE! =

#VALUE! (kN/m2) #VALUE!

TÝnh cho phÇn tö thø hai: #VALUE! #VALUE! #VALUE!

σx {σ}

e

2

=

σy

=

[D][B] x

τxy

#VALUE!

#VALUE! =

#VALUE! #VALUE!

2

#VALUE! (kN/m2) #VALUE!

TÝnh cho phÇn tö thø ba: 0.00E+00 0.00E+00 0.00E+00

σx {σ}

e

3

=

σy

=

[D][B] x

τxy

0.00E+00

#VALUE! =

#VALUE! #VALUE!

3

#VALUE! (kN/m2) #VALUE!

TÝnh cho phÇn tö thø t­: #VALUE! #VALUE! #VALUE!

σx {σ}

e

4

=

σy

=

[D][B] x

τxy

#VALUE!

#VALUE! =

#VALUE! #VALUE!

4

#VALUE! (kN/m2) #VALUE!

TÝnh cho phÇn tö thø n¨m 0.00E+00 0.00E+00 #VALUE!

σx {σ}

e

1

=

σy τxy

=

[D][B] x

#VALUE! #VALUE!

#VALUE! =

#VALUE! (kN/m2) #VALUE!

5

#VALUE!

TÝnh cho phÇn tö thø s¸u: #VALUE! #VALUE! #VALUE!

σx {σ}

e

6

=

σy

=

[D][B] x

τxy

#VALUE!

#VALUE! =

#VALUE! #VALUE!

6

#VALUE! (kN/m2) #VALUE!

TÝnh cho phÇn tö thø b¶y: 0.00E+00 0.00E+00 0.00E+00

σx {σ}

e

7

=

σy

=

[D][B] x

τxy

0.00E+00

#VALUE! =

#VALUE! #VALUE!

7

#VALUE! (kN/m2) #VALUE!

TÝnh cho phÇn tö thø t¸m: #VALUE! #VALUE! #VALUE!

σx {σ}

e

8

=

σy

=

[D][B] x

τxy

#VALUE!

#VALUE! =

#VALUE! #VALUE!

8

#VALUE! (kN/m2) #VALUE!

TÝnh cho phÇn tö thø chÝn: 0.00E+00 0.00E+00 #VALUE!

σx {σ}

e

9

=

σy

=

[D][B] x

#VALUE!

#VALUE! =

#VALUE! (kN/m2)

τxy

#VALUE! #VALUE!

9

#VALUE!

TÝnh cho phÇn tö thø m­êi: #VALUE! #VALUE! #VALUE!

σx {σ}

e

10

=

σy

=

[D][B] x

τxy

#VALUE!

#VALUE! =

#VALUE! #VALUE!

10

#VALUE! (kN/m2) #VALUE!

TÝnh cho phÇn tö thø m­êi mét: 0.00E+00 0.00E+00 0.00E+00

σx {σ}

e

11

=

σy

=

[D][B] x

τxy

0.00E+00

#VALUE! =

#VALUE! #VALUE!

11

#VALUE! (kN/m2) #VALUE!

TÝnh cho phÇn tö thø m­êi hai: #VALUE! #VALUE! #VALUE!

σx {σ}

e

12

=

σy

=

[D][B] x

τxy 12

#VALUE! #VALUE! #VALUE!

#VALUE! =

#VALUE! (kN/m2) #VALUE!

TÝnh cho phÇn tö thø m­êi ba:

σx

0.00E+00 0.00E+00 #VALUE!

#VALUE!

{σ}e

13

=

σy

=

[D][B] x

τxy

#VALUE!

=

#VALUE! #VALUE!

13

#VALUE! (kN/m2) #VALUE!

TÝnh cho phÇn tö thø m­êi bèn: #VALUE! #VALUE! #VALUE!

σx {σ}

e

14

=

σy

=

[D][B] x

τxy

#VALUE!

#VALUE! =

#VALUE! #VALUE!

14

#VALUE! (kN/m2) #VALUE!

TÝnh cho phÇn tö thø m­êi n¨m: 0.00E+00 0.00E+00 0.00E+00

σx {σ}

e

15

=

σy

=

[D][B] x

τxy

0.00E+00

#VALUE! =

#VALUE! #VALUE!

15

#VALUE! (kN/m2) #VALUE!

TÝnh cho phÇn tö thø m­êi s¸u: #VALUE! #VALUE! #VALUE!

σx {σ}e

16

=

σy

=

τxy 16

[D][B] x

#VALUE! #VALUE! #VALUE!

#VALUE! =

#VALUE! (kN/m2) #VALUE!

chuyÓn vÞ nót cña phÇn tö

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