å 为C20æ··ååçé
å¶å¼ºåº¦ä¸º29.87MPaï¼è使ç¨å½æ 32.5级
æ®éæ°´æ³¥æè½é
å¶åºç
æ··åå强度为23.07MPaï¼æ以混åå强度没æä¿è¯ã
äºã计ç®é¢
1.欲é
å¶C30æ··ååï¼è¦æ±å¼ºåº¦ä¿è¯ç95%ï¼åæ··ååçé
å¶å¼ºåº¦ä¸ºå¤å°?
è¥éç¨æ®éæ°´æ³¥,åµç³æ¥é
å¶,è¯æ±æ··ååç
æ°´ç°æ¯.
å·²ç¥:æ°´æ³¥å®é
强度为48MPa,A=0.46,B=0.07
解:fcu,0=30+1.645Ã5.0=38.2 MPa
fcu=Afce(C/W-B)
å³ 38.2=0.46Ã48(C/W-0.07)
â´W/C=0.56
2.æææçå¯åº¦ä¸º2.68g/cm3ï¼
表è§å¯åº¦ä¸º2.34 g/cm3ï¼720å
ç»å¹²ç该ææ浸水饱ååæ¦å¹²è¡¨é¢å¹¶æµå¾è´¨é为740å
ãæ±è¯¥ææç
åéçãè´¨éå¸æ°´çãä½ç§¯å¸æ°´çãå¼å£åéçãéå£åéçåè§å¯åº¦ï¼è¿ä¼¼å¯åº¦ï¼ã(åå®å¼å£åå
¨å¯å
满水)
.解: åéç P=(1-2.34/2.68)Ã100%=12.7%
è´¨éå¸æ°´ç β=(740-720)/720=2.8%
ä½ç§¯å¸æ°´ç βâ=2.8%Ã2.34=6.6%
å¼ååéç På¼=βâ=6.6%
éå£åéç Pé=P-På¼=12.7%-6.6%=6.1%
è§å¯åº¦ Ïâ=m/(V+Vé)=Ï0/(1-P+Pé)
=2.34/(1-12.7%+6.1%)
=2.50 g/cm3
3. å·²ç¥æ··ååè¯æè°æ´åæ ¼ååææç¨é为ï¼æ°´æ³¥5.72kgï¼
ç å9.0kgï¼ç³å为18.4kgï¼æ°´ä¸º4.3kgã并æµå¾æåç©è¡¨è§å¯åº¦ä¸º2400kg/m3ï¼è¯æ±å
¶åºåé
åæ¯(以1m3æ··ååä¸åææç¨é表示)ã
è¥éç¨å®æµå¼ºåº¦ä¸º45MPaçæ®éæ°´æ³¥ï¼
æ²³ç ,åµç³æ¥é
å¶,è¯ä¼°ç®è¯¥æ··ååç28天强度(A=0.46ï¼B=0.07)ã
解: åºåé
åæ¯ä¸º
C=5.72Ã2400/(5.72+9+18.4+4.3)=367 kg
S=9Ã2400/(5.72+9+18.4+4.3)=577 kg
G=18.4Ã2400/(5.72+9+18.4+4.3)=1180 kg
W=4.3Ã2400/(5.72+9+18.4+4.3)=275 kg
fcu=0.46Ã45Ã(367/275-0.07)
=26.2 MPa
4.å·²ç¥æææçå¯åº¦ä¸º2.50g/cm3, è§å¯åº¦ä¸º2.20g/cm3, 表è§å¯åº¦ä¸º2.00g/cm3 ãè¯æ±è¯¥ææçåéçãå¼å£åéçåéå£åéçã
解:åéçP=(1-2/2.5)Ã100%=20%
å¼å£åéçPå¼=(1-2/2.2)Ã100%
éå£åéç Pé=P-På¼
5. å·²ç¥ç ¼çæ½å·¥é
åæ¯ä¸º1:2.40:4.40:0.45ï¼ä¸å®æµæ··ååæåç©ç表è§å¯åº¦ä¸º2400kg/m3.ç°åºç ç
å«æ°´ç为2.5%ï¼ç³åçå«æ°´ç为1%ãè¯è®¡ç®å
¶å®éªå®¤é
åæ¯ãï¼ä»¥1m3æ··ååä¸åææçç¨é表示ï¼åè³1kgï¼
解:mc=1Ã2400/(1+2.4+4.4+0.45)
ms=2.4mc/(1+2.5%)
mg=4.4mc/(1+1%)
mw=0.45mc+2.5%ms+1%mg
6.æ··ååç设计强度ç级为C25ï¼è¦æ±ä¿è¯ç95%ï¼å½ä»¥ç¢ç³ã42.5æ®éæ°´æ³¥ãæ²³ç é
å¶æ··ååæ¶ï¼è¥å®æµæ··åå7 d
æå强度为20MPaï¼åæ··ååçå®é
æ°´ç°æ¯ä¸ºå¤å°ï¼è½å¦è¾¾å°è®¾è®¡å¼ºåº¦çè¦æ±ï¼ï¼A=0.48,B=0.33,æ°´æ³¥å®é
强度为43MPï¼
.解: å®é
æ··åå f28=f7Ãlg28/lg7
=20Ãlg28/lg7=34.2 MPa
C25æ··ååè¦æ±:fcu=25+1.645Ã5=33.2 MPa
âµf28=34.2 MPaï¼fcu=33.2 MPa
â´è¾¾å°äºè®¾è®¡è¦æ±.
åfcu=Afce(C/W-B)
å³34.2=0.48Ã43Ã(C/W-0.33)
â´W/C=0.50
7ãä¸åæ åçæ®éç²åç ï¼å
¶å°ºå¯¸ä¸º240Ã115Ã53mmï¼å·²ç¥å¯åº¦ä¸º2.7g/cm3ï¼å¹²ç¥æ¶è´¨é为2500gï¼å¸æ°´é¥±åæ¶è´¨é为2900gãæ±ï¼ï¼1ï¼ææç干表è§å¯åº¦ã
ï¼2ï¼ææçåéçã
ï¼3ï¼ææçä½ç§¯å¸æ°´çã
è§£ï¼ (1ï¼æ ¹æ®1ãÏ0=m/v=2500/240Ã115Ã53=1.7 g/cm3
(2)ãP=1-Ï0/Ï=1-1.7/2.7=37%
(3)ãWv= WmÏ0=(2900-2500)/2500?1.7=27%
8ã计ç®æ大桥混åå设计强度ç级为C40ï¼å¼ºåº¦
æ å差为6.0Mpaï¼ç¨52.5级
ç¡
é
¸çæ°´æ³¥ï¼å®æµ28dçæå强度为58.5 Mpaï¼å·²ç¥
æ°´æ³¥å¯åº¦ÏCï¼3.10g/cm3ï¼ä¸ç ï¼ç å表è§å¯åº¦ ÏOSï¼3.10g/cm3ï¼ç¢ç³ï¼ç³å表è§å¯åº¦ÏOGï¼278g/cm3ãèªæ¥æ°´ãå·²ç¥ï¼A=0.46ï¼B=0.07ï¼åä½ç¨æ°´é为195kg/m3ï¼ç çSp=0.32 å«æ°é
ç¾åæ°ä¸ºÉ=1ï¼æ±è¯¥æ··ååçåæ¥é
åæ¯ï¼ï¼Wï¼Cæ大水ç°æ¯ä¸º0.60ï¼æ°´æ³¥æå°ç¨é为280 kg/m3ï¼
解ï¼ï¼1ï¼ fcu,t=fcu,k+1.645Ï fcu,t=40+1.645Ã6= 49.87Mpa
(2) W/C=Afce/fcu,t+ABfce W/C=0.46Ã58.5/49.87+0.46Ã0.07Ã58.5=0.52
(3) å 为0.52<0.60ï¼æ以C0=W0/W/C=195/0.52=375kgï¼å 为375>280ï¼æ以C0=375kg
æ ¹æ®ä½ç§¯æ³æ±ç ãç³ç¨é
C0/ÏC+W0/ÏW+S0/Ïos+G0/ÏoG+0.01α=1
S0/ S0+G0=SP æ以
375/3100+195/1000+ S0/3100+G0/2780+0.01 =1
S0/ S0+G0=0.32
æ以S0=616 G0=1310
æ以该混ååçåæ¥é
åæ¯ï¼æ°´æ³¥ï¼375kg ç åï¼616kg ç³åï¼1310kg æ°´ï¼195kg
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