圆盘耙播种机

第六章bh300mm600mmaa'40mm，混凝土强度等级为C30，f=14.3N/mm2, HRB335级，fy=f300N/mm2，0.550，柱的计算长度l sA'402mm2（求：受拉钢筋截面面积As。解：⑴求ei、η、ese

180

eaeie0ea300200.5fcA0.514.33006002.415 取1l030005

1

1400

(0h

1

1320521.01.0 e

h2

1.03320600402ei1.03320329.6mm0.3h00.3560

e'

h/2a'1.03320 4069.6mm 由Ne ' xf'A'ha'1fcbfx

6001035901.014.3300x5600.5x300402560x21120x135698.6解得x1981.7mm(舍去)x2sx2a'xbsNafbxfA'f1 y yfbx fA 1 A sAs

379.7mm2minbh0.002300600选用受拉钢 ，As402mm已知一偏心受压柱的轴向力设计值N=400KN,弯矩M=180KN·m,截面尺寸bh300mm500m,

a'40mm,计算长度

=6.5m,混凝土等级为C30 fc=14.3N/mm2，钢筋为 fy

f'300Nmm2yye

180400

h

16.7mmeaeie0ea450200.5fcA0.514.33005002.681 4001l0h65005001315，21.0 l1 eh01400i

11 1400

1.01.01.12e

h2

1.12470500402ei1.12470526.4mm0.3h00.3460 fb fs1 1s

E 2105b则sA's

0byf'ha' 0bys400103736.41.014.330046020.550(10.5300(460As按构造配 As

'

bh0.002300500300mms由公式s1Ne1Nef'A'(ha'y f21 400736.4103300300(460112 fbh fA 1 0 A s 1.014.33004600.341400103300

，As=已知偏心受压柱的截面尺寸为bh300mm400mm，混凝土为C25级，yfc=11.9N/mm2HRB335fyf'300Nmm2,Ny

=求界限偏心距C25级混凝土,fc11.9NmmHRB3352查表得b0.550ho365mmA’sAs已经给定，故相对界限偏心距e0bh0ob b 1 b b 0.5afbh(hh)0.5(f'Aob b 1 b b N (afbh

'

y y fA b 1 b y y 2(0.55011.9300365300804300628)eob0.506365185mmea20mmei20020220mmeieob1loh500040012.515，故21.01

(12.5)21.01.0eeih/2a1fbxf'A'f 1 y y'sNefbx(h

)

A(ha' 1 y N11.9300x300804300N425.71.011.9300x(3650.5x)300804(365l0b500030016.7,查表得，N0.9(fAf'A' y1421KN4．某一矩形截面偏心受压柱的截面尺寸bh300mm500mm,计算长度sl06masa'40mmC30，fc=14.3N/mm211.0,HRB335se

121.41512

h50016.7mm eaeie0ea80.3200.5fcA0.514.3300500 1512 h600012 l

1 1

140011400

1220.709eeih2as1.233100.3500/240ei1.233100.3124.2mm0.3h00.3460hhe' ' 124.24085.8mmi ssAs=ρminbh0.002300500300mmNefbxxa'fAxh01(ha

1 y

2fA(ha' 2fy x2y

]x[ 1y (ha')]fbh( f fb( 1 1 1 x273.24x107426.01x1293.23mmx2366.42mm(舍去满足bh0xxNefbx(hxfyAha'1 A'Ne1fcbxh0 s f'ha' s

'1512103347.61.014.3300293.23(4600.5300(460选 ，As'cN1512103fA14.33005002145103c已知一矩形截面偏心受压柱的截面尺寸bh300mm400mm,syl03.0masa'35mmC35，fc=16.7N/mm2,HRB400级钢筋配筋，fy=f360N/mm2,N400KN,M235.2KN·m,对称配筋，syAsA'se

235.2400

eaeie0ea588200.5fcA0.516.73004002.505 4001 h30007.5 l

1 1400 1

16087.521.01400 1.024e

h2

1.02460840035ei1.024608622.6mm0.3h00.3365A和 As

所以 fbh1.016.73001 Nefbh210.5'1c0 f'ha''1c0

0.219365 400103787.71.016.73003652(0.2190.52037mm2'bh0.002300400解：⑴求ei、η、ee

h2

137.6500402Nb1fcbh0b1.014.3300460N1512KNNb1085.4KNNe0.43fbh1 0f

1 15121030.5501.014.33001512103347.60.4314.330046021.014.3300

x0.681460ssA'Ne1fcbxh0y f'ha'y 1512103347.61.014.3300313.3(4600.5300(460935.3mm2minbh0.002300500300mm ，AsAs已知某柱子截面尺寸bh200mm400mm

sa'35mmsyfc=11.9N/mm2,钢筋用HRB335级，fy=f’=300N/mm2，钢筋采 ，对称配筋，yAA226mm2,l=3.6m,e100mm, h40013.3mm eaeie0ea10020取1 h36009 l

1 1400

1120921.0 1.176e

h2

1.176120400352N 0.5fbh(hh)0.5(f'A'fA)(h2a) b 1c b0 b0 ys ys fbhf'A'fAN 1 b y yNfbxf'A'1f1 b y

x1.011.9200x300226

3123x又由Ne xf'A'ha'1fcbx 2 N306.121.011.9200x(3650.5x300226365整理得：N2839x3.889x273117 联立（A）(B)两式，解得x205mm,代入（A）式中得：NN值，重新求出1、值：0.5fcA0.511.9200400 1.717，与原来的1NC30，aa'35mm，fc=14.3N/mm2,HRB400,fy=f=360N/mm2,轴向力设计值 N800KNM=246KN·m求钢筋截面面积。解：⑴求ei、η、eh0has70035e

246

h70023.3mm eaeie0ea307.523.30.5fcA0.514.31300001.162 8001 h68009.71 l

1 1

140011400

(9.71)21.01.01.135e

h2

1.135330.8700352Tfc

NT800103429

1.014.31000.390bxh00.390665259.4mm120mmA Nefbxh0.5xfb'bh'h0.5h'A 1

1 f'

h0a's 800103690.51.014.3100259.4(6650.5259.4)1.014.3250120(665 360(665s选 ，AsA'452mms,cyaa'40mmC30，f=14.3N/mm2HRB400，f=f360N/mm2,cy 1N=2N=704.8KN，M3N=1200KN，M=解：Ⅰ、求解第1组内力e

378.3

h80026.67mm eaeie0ea687.826.670.5fcA0.514.31700002.21 取1 h68008.5 l

1

140011400

(8.5)21.0取e

1.05714.5800402Nfbh+f(b' 1 0 1 N550KN1206.5KNe'e a'1.05714.5 40390.23mm N1fc

b)hf5501031.014.33001501.014.3100s取x2a'240sA

N

ha' f'(ha'

s550103390.23828mm2360(76040)s假设A's0，由NfNy则AsNyf

550

取A A}828mm2 A0.002(1008002300150) 2e

280

h80026.67mm eaeie0ea397.326.670.5fcA0.514.31700001.725 1 h68008.5 l

1 1

140011400

8.521.0e

h2

1.09423.97800402N704.8KN1206.5KNe'ei a'1.09423.97

40sN1f(b'

7041031.014.3300150 fx

1.014.3100s0.05676042.9mm2a'sx

N(eha'由公式AsA'sf

y(hoa'sy704.8103102.13360(76040)

277.7mm2 A0.002(1008002300150)340mm3e

3601200

h80026.67mm eaeie0ea30026.670.5fcA0.514.31700001.03 12001 h68008.5 l

1 1

140011400

8.521