À¥Ã÷Àí¹¤´óѧÀíÂÛÁ¦Ñ§BÁ·Ï°²áÌâ+½â´ð ÏÂÔØ±¾ÎÄ

ÀíÂÛÁ¦Ñ§B£¨1) Á·Ï°²á 32ѧʱ À¥Ã÷Àí¹¤´óѧ

רҵ ѧºÅ ÐÕÃû ÈÕÆÚ ³É¼¨

F2CE¸ËÊÜÀ­Á¦ 2.2.3 ÔÚˮƽÁºÉÏ×÷ÓÃ×ÅÁ½¸öÁ¦Å¼£¬ÆäÖÐÒ»¸öÁ¦Å¼¾ØM1=60kN.m£¬ÁíÒ»¸öÁ¦Å¼¾ØM2=40kN.m£¬FCDÒÑÖªAB=3.5m£¬ÇóA¡¢BÁ½Ö§×ù´¦µÄÔ¼Êø·´Á¦¡££¨´ð°¸£ºFA=5.7kN£© M1 M2 ½â£ºÈ¡ÁºÎªÑо¿¶ÔÏó ¡ßÁ¦Å¼Ö»ÄÜÓÃÁ¦Å¼Æ½ºâ£¬¡àFA = FB A B C M?03.5FA-M1?M2?03.5m F AFB M?M260?40 ?FA?FB?1??5.71kN·½ÏòÈçͼ¡£ 3.53.5

2.2.4 ѹե»ú¹¹ÈçͼËùʾ£¬¸ËAB¡¢BCµÄ×ÔÖØ²»¼Æ£¬A¡¢B¡¢C´¦¾ùΪ½ÂÁ´Á¬½Ó¡£ÓͱÃѹÁ¦F=3kN£¬·½Ïòˮƽ£¬h=20mm£¬l=150mm£¬ÊÔÇ󻬿éCÊ©ÓÚ¹¤¼þµÄѹÁ¦¡££¨´ð°¸£ºFC=11.25kN£©

y A ½â£º1£©È¡Ïú¶¤BΪÑо¿¶ÔÏó£¬ÉèAB¡¢BC¸Ë¾ùÊÜÀ­Á¦

h x l Y?0FABsin??FBCsin??0?FBC?FABB ¦Á F X?0?FABcos??FBCcos??F?0¦Á

FAB l ?FBC??F2cos?¦Á B F¦Á C 2£©È¡»¬¿éCΪÑо¿¶ÔÏó£º

FBC F'BCY?0F'BCsin??FC?0

¦Á ?FC??F'BCsin??F?tg?2?Fl2h?11.25kN XC FC(?)¡à»¬¿éCÊ©ÓÚ¹¤¼þµÄѹÁ¦Îª£º F'C?11.25kN

2.2.5 ÖØÎªPµÄ¾ùÖÊÔ²Çò·ÅÔÚ°åABÓëǽ±ÚACÖ®¼ä£¬D¡¢EÁ½´¦¾ùΪ¹â»¬½Ó´¥£¬³ß´çÈçͼʾ£¬Éè

??????°åABµÄÖØÁ¿²»¼Æ£¬ÇóA´¦µÄÔ¼Êø·´Á¦¼°ÉþBCµÄÀ­Á¦¡££¨´ð°¸£ºFC= FT = 23 P/3£»£© ½â£º1£©È¡¾ùÖÊÔ²ÇòΪÑо¿¶ÔÏó£º

B C B

Y?0-P?FDsin300?0?FD?2PFT60?

2£©È¡°åABΪÑо¿¶ÔÏó£º

l/2 l/2 O E F'DD D Y?0FAsin600?F'Dsin300?0

P 0 ?F?Psin60?23P3·½ÏòÈçͼ A60? 30? l/2 l/2 FA

00X?0?FAcos60?F'Dcos30?FT?0

A A 00?F??Fcos60?F'cos30TADy

???FEO x6

??23P1323?2P?P3223ÀíÂÛÁ¦Ñ§B£¨1) Á·Ï°²á 32ѧʱ À¥Ã÷Àí¹¤´óѧ

רҵ ѧºÅ ÐÕÃû ÈÕÆÚ ³É¼¨

E 300 ·½ÏòÈçͼ

2.2.6 ¶Í´¸¹¤×÷ʱ£¬ÈçÊܹ¤¼þ¸øËüµÄ·´×÷ÓÃÁ¦ÓÐÆ«ÐÄ£¬Ôò»áʹ¶Í´¸C·¢Éúƫб£¬Õ⽫ÔÚµ¼¹ìD FDABÉϲúÉúºÜ´óµÄѹÁ¦£¬´Ó¶ø¼ÓËÙµ¼¹ìµÄÄ¥Ëð²¢Ó°Ïì¶Í¼þµÄ¾«¶È¡£ÒÑÖª´ò»÷Á¦F=100kN£¬Æ«ÐÄ

P¾àe=20mm£¬¶Í´¸¸ß¶Èh=200mmÊÔÇó¶Í´¸¸øµ¼¹ìÁ½²àµÄѹÁ¦¡££¨´ð°¸£ºFN=10kN£©

F FB B C h A F FAe ½â£ºÈ¡¶Í´¸ÎªÑо¿¶ÔÏó

¡ßÁ¦Å¼Ö»ÄÜÓÃÁ¦Å¼Æ½ºâ£¬¡àFA = FB ?M?0F?e?FA?h?0?FFF?e100?20A?B?h?200?10kN·½ÏòÈçͼ ¶Í´¸¸øµ¼¹ìÁ½²àµÄѹÁ¦·Ö±ðÊÇ FAºÍFBµÄ·´×÷ÓÃÁ¦

7

ÀíÂÛÁ¦Ñ§B£¨1) Á·Ï°²á 32ѧʱ À¥Ã÷Àí¹¤´óѧ

רҵ ѧºÅ ÐÕÃû ÈÕÆÚ ³É¼¨

µÚ¶þÕÂ Æ½ÃæÁ¦Ïµ£¨ÈÎÒâÁ¦Ïµ£©

Ò»¡¢ ÊÇ·ÇÅжÏÌâ

2.1.1Ò»¸öÈÎÒâÁ¦ÏµµÄºÏÁ¦Ê¸ÊÇÖ÷ʸ¡£ £¨ ¡Á £© 2.1.2Ä³Æ½ÃæÈÎÒâÁ¦ÏµÏòA¡¢BÁ½µã¼ò»¯µÄÖ÷¾Ø½ÔΪÁ㣬¼´MA=MB=0£¬´ËÁ¦Ïµ¼ò»¯µÄ×îÖÕ½á¹ûΪ£º

A¡¢¿ÉÄܼò»¯ÎªÒ»¸öÁ¦¡£ £¨ ¡Å £© B¡¢¿ÉÄܼò»¯ÎªÒ»¸öÁ¦Å¼¡£ £¨ ¡Á £© C¡¢¿ÉÄÜÆ½ºâ¡£ £¨ ¡Å £©

2.1.3ÈôÆ½ÃæÆ½ÐÐÁ¦ÏµÆ½ºâ£¬¿ÉÒÔÁгöÈý¸ö¶ÀÁ¢µÄƽºâ·½³Ì¡££¨1¸ö£© £¨ ¡Á £© 2.1.4Æ½ÃæÈÎÒâÁ¦ÏµµÄÈý¸ö¶ÀÁ¢Æ½ºâ·½³Ì²»ÄÜÈ«²¿²ÉÓÃͶӰ·½³Ì¡£ £¨ ¡Å £© 2.1.5Æ½ÃæÁ¦ÏµÖУ¬ÈôÆäÁ¦¶à±ßÐÎ×ÔÐбպϣ¬ÔòÁ¦ÏµÆ½ºâ¡£ £¨ ¡Á £©

¶ÔÒ»¿Õ¼äÈÎÒâÁ¦Ïµ£¬ÈôÆäÁ¦¶à±ßÐÎ×ÔÐзâ±Õ£¬Ôò¸ÃÁ¦ÏµµÄÖ÷ʸΪÁã¡££¨ ¡Ì £©

2.1.6 ¾²²»¶¨ÎÊÌâµÄÖ÷ÒªÌØµãÊÇÆäδ֪Á¿µÄ¸öÊý¶àÓÚϵͳ¶ÀÁ¢Æ½ºâ·½³ÌµÄ¸öÊý£¬ËùÒÔδ֪Á¿²»ÄÜÓÉÆ½ºâ·½³Ìʽȫ²¿Çó³ö¡£ £¨ ¡Å £©

¶þ¡¢ Ìî¿ÕÌâ

2.2.1Ôڱ߳¤ÎªdµÄÕý·½ÐÎABCDËùÔÚÆ½ÃæÄÚ£¬×÷ÓÃÒ»Æ½ÃæÈÎÒâÁ¦Ïµ£¬¸ÃÁ¦ÏµÏòAµã¼ò»¯£º¡ÆMA=0£¬ÏòBµã¼ò»¯£º¡ÆMB =£­Fd£¨Ë³Ê±Ê²×ªÏò£©£¬ÏòDµã¼ò»¯£º¡ÆMD =Fd£¨ÄæÊ±ÕëתÏò£©¡£

2 FÔò´ËÁ¦Ïµ¼ò»¯µÄ×îºó½á¹ûΪ F R ? ·½ÏòÈçͼ £¨Ðè˵Ã÷´óСºÍ·½Ïò»òÔÚͼÖбê³ö£©¡£

A D

2 2?M?F?d?F?dDRd 22 2FFR2?F??2FdR 22 B C d 2.2.2ÈçͼËùʾ¸÷½á¹¹£¬Êô¾²²»¶¨µÄ½á¹¹ÊÇ (a), (c), (d) ¡£ ×¢Ò⣺²»ÄÜÓÃm=2n-3Åбð¡£

P P P

?8

ÀíÂÛÁ¦Ñ§B£¨1) Á·Ï°²á 32ѧʱ À¥Ã÷Àí¹¤´óѧ

רҵ ѧºÅ ÐÕÃû ÈÕÆÚ ³É¼¨

£¨a£© (b) (c) (d)

2ѧʱ Èý¡¢¼ÆËãÌâ

2.3.1 °Ñ×÷ÓÃÔÚÆ½°åÉϵĸ÷Á¦ÏòµãO¼ò»¯£¬ÒÑÖªF1=300kN£¬F2=200kN£¬F3=350kN£¬F4 =250kN£¬ÊÔÇóÁ¦ÏµµÄÖ÷ʸºÍ¶ÔµãOµÄÖ÷¾ØÒÔ¼°Á¦ÏµµÄ×îºóºÏ³É½á¹û¡£Í¼Öг¤¶Èµ¥Î»Îªcm¡£

£¨´ð°¸£ºFR=678.86kN£¬MO=4600 kN.cm£¬d=6.78©M£¬¦Á=60£©

0

2.3.2 ¶Ìì³§·¿Á¢ÖùµÄµ×²¿ÊDZ­Ðλù´¡£¬Á¢Öùµ×²¿ÓûìÄýÍÁɰ½¬Óë±­Ðλù´¡¹ÌÁ¬ÔÚÒ»Æð£¬ÒÑÖªµõ³µÁº´«À´µÄÇ¦Ö±ÔØºÉF=60kN£¬·çºÉq=2kN/m£¬ÓÖÁ¢Öù×ÔÉíÖØP=40kN£¬a=0.5m£¬h=10m£¬ÊÔÇóÁ¢Öùµ×²¿µÄÔ¼Êø·´Á¦¡££¨´ð°¸£ºFAx=20kN£¬FAy=100kN£¬MA=130 kN.m£© a ½â£ºÈ¡Á¢ÖùΪÑо¿¶ÔÏó£º

?XA??qh??20kN(?)?X?0XA?qh?0F

?YA?P?F?100kN(?)Y?0YA?P?F?0?y

q qh2 xh ?MA?0MA?2?Fa?0P

qh2YA?MA??Fa?100?30?130kNm£¨ £©

2

XAA

MA A

2.3.3 ÊÔÇóÏÂÁи÷ÁºµÄÖ§×ù·´Á¦¡£[´ð°¸£º£¨a£©FAy=2qa£¬MA=5qa2/2£»(b)FAx=0£¬FAy=3kN£¬FB=24.6kN]

q MA qa ½â£ºÈ¡ÁºÎªÑо¿¶ÔÏó£º

C ?X?0XA?0 A a a B ?Y?0YA?qa?qa?0?YA?2qa(?) y 00F1 Y?Fsin45?F?Fsin30?587.13kN123F3 30? 45? F2 22F'?(X)?(Y)?678.96kN ??R5 20 ?X?0.502cos???Y?0.865 'cos??FRFRF4 x FR'FR' O1 5 M0O M0??M0(Fi)?25F1cos450?10F2?25F3cos300 d10 25 ?35F3sin300?5F4?4600.58kN?cm

d?M0FR?6.78cmÁ¦ÏµµÄ×îºóºÏ³É½á¹ûΪ£º FR?F'R?678.96kN½â£º ?X?-F1cos450?F3cos300?F4?340.98kN?XAyYA(a) x9

ÀíÂÛÁ¦Ñ§B£¨1) Á·Ï°²á 32ѧʱ À¥Ã÷Àí¹¤´óѧ

רҵ ѧºÅ ÐÕÃû ÈÕÆÚ ³É¼¨

qa2?MA?0MA?2?2qa2?0

qh2 52£¨ £© 2YA½â£ºÈ¡ÁºÎªÑо¿¶ÔÏó£ºYB?M??2qa?qaAF=20kN M=8kN.m q=2kN/m 22

X?0XA?0? C D B A X0.82qA M?0?M?1.6YB?2.4F?0?A0.8m 0.8m 0.8m 0.8m 2

1y(b) ?YB?(?0.82?8?48)?24.6kN(?)

1.6 x?Y?0YA?0.8q?YB?F?0?YA?-3kN(?)

2.3.4 Ðü±Ûʽµõ³µµÄ½á¹¹¼òͼÈçͼËùʾ£¬ÓÉDE¡¢AC¶þ¸Ë×é³É£¬A¡¢B¡¢CΪ½ÂÁ´Á¬½Ó¡£ÒÑÖªP1=5kN£¬P2=1kN£¬²»¼Æ¸ËÖØ£¬ÊÔÇó¸ËAC¸ËËùÊܵÄÁ¦ºÍBµãµÄÖ§·´Á¦¡£

£¨´ð°¸£ºFBx=3.33kN£¬FBy=0.25kN£¬FAC=6.65kN£©

½â£ºÈ¡DE¸ËΪÑо¿¶ÔÏó: 1m 2.5m 0 2m P?1?Fsin60?2?P1?2.5?0M?02AC?BB E D 1 C 60? P2 ?FAC?(2.5P 1?P2)?6.64kN 3 F'AC?FAC?6.64kN£¨£©¡à¸ËACÊÜѹ yXB?FACcos600?0X?0?P1 x?XB??FACcos600??3.32kN(?) A 0 Y?P?Fsin60?P1m Y?02.5m B2AC1?0? 2m B 3E D ?Y?P?P?6.64??0.25kN(?)B21C 60? P2 XB 2P1

YBFAC

2.3.5 ÓÉACºÍCD¹¹³ÉµÄ×éºÏÁ»Í¨¹ý½ÂÁ´CÁ¬½Ó£¬ËüµÄÖ§³ÐºÍÊÜÁ¦ÈçͼËùʾ£¬ÒÑÖª¾ù²¼ÔغÉÇ¿¶Èq=10kN/m£¬Á¦Å¼¾ØM=40kN.m£¬²»¼ÆÁºÖØ£¬ÇóÖ§×ùA¡¢B¡¢DµÄÔ¼Êø·´Á¦ºÍ½ÂÁ´C´¦ËùÊܵÄÁ¦¡£

£¨´ð°¸£ºFB=40kN£¬FAy=15kN£¬FC=5 kN £¬FD=15 kN£©

A 2m y x YAXAA 2m q B 2m C 2m q C 2m XCYCq ½â£ºÈ¡CDΪÑо¿¶ÔÏó X?0M D MC?02q?1?M?4YD?0 2m Y?0YC?2q?YD?0 M ?XC?0?YD?15kN(?)?YC?5kN(?)??D 2m È¡ACΪÑо¿¶ÔÏó£º

YD?X?0?M10

B'XA?XC?XC?0?0 B 2m XC 'C-2YA?2q?1?2Y'C?0?YA??15kN(?)?Y?0YA?YB?2q?Y'C?0?YB?40kN(?)YC'