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。第四章轴心受力构件4.1验算由2∟635组成的水平放置的轴心拉杆的强度和长细比。轴心拉力的设计值为270KN,只承受静力作用,计算长度为3m。杆端有一排直径为20mm的孔眼(图4.37),钢材为Q235钢。如截面尺寸不够,应改用什么角钢?注:计算时忽略连接偏心和杆件自重的影响。解:(1)强度查表得∟635的面积A=6.14cm2,ii1.94cm,minxA2(Adt)2(614205)1028mm2,N=270KNnN270103262.6Mpaf215Mpa,强度不满足,A1028nN270103所需净截面面积为A1256mm2,nf2151256所需截面积为AAdt205728mm2,n2选636,面积A=7.29cm2729mm2728mm2(2)长细比l3000o154.6350i19.4min4.2一块-40020的钢板用两块拼接板-40012进行拼接。螺栓孔径为22mm,排列如图4.38所示。钢板轴心受拉,N=1350KN(设计值)。钢材为Q235钢,解答下列问题;(1)钢板1-1截面的强度够否?(2)是否需要验算2-2截面的强度?假定N力在13个螺栓中平均分配,2-2截面应如何验算?(3)拼接板的强度够否?解:(1)钢板1-1截面强度验算:A(b3d)t(400322)206680mm2,N=1350KNn10minN1350103202.1Mpaf205Mpa,强度满足。A6680n1-可编辑修改- 。(2)钢板2-2截面强度验算:(a),种情况,(a)是最危险的。A(l5d)t(40080802802522)206463mm2,N=1350KNn2(a)0N1350103208.9Mpaf205Mpa,但不超过5%,强度满足。A6463n2对应图(d)的验算:A(l5d)t(400522)205800mm2,n2(d)01010NN13501038.5KN1313N1038.5103179.0Mpaf205Mpa,强度满足。A5800n2(3)拼接板的强度够否?因为拼接板厚度21224mm20mm,所以不必验算拼接板。4.3验算图4.39所示用摩擦型高强度螺栓连接的钢板净截面强度。螺栓直径20mm,孔径22mm,钢材为Q235AF,承受轴心拉力N=600KN(设计值)。解:(1)净截面验算:A(b3d)t(240322)142436mm2,n0minN600NN0.536000.53500KN99N500103205.3Mpaf215Mpa,强度满足。A2436n(2)全截面验算-可编辑修改- 。N600103178.6Mpaf215Mpa,强度满足。A240144.4一水平放置两端铰接的Q345钢做成的轴心受拉构件,长9m,截面由2∟908组成的肢尖向下的T形截面,问是否能承受设计值为870KN的轴心力?解:(1)强度验算查表得∟908的面积A=13.94cm2,ii2.76cm,minxN870103312.1Mpaf310Mpa,但不超过5%,强度满足。A13942(2)刚度验算l90000326350i27.6min4.5某车间工作平台柱高2.6m,按两端铰接的轴心受压柱考虑。如果柱采用I16(16号热轧工字钢),试经过计算解答:(1)钢材采用Q235钢时,设计承载力为多少?(2)改用Q345钢时,设计承载力是否显著提高?(3)如果轴心压力为330KN(设计值),I16能否满足要求?如不满足,从构造上采取什么措施就能满足要求?解:(1)钢材采用Q235钢时,设计承载力为多少?查表得I16的面积A=26.1cm2,i6.57cm,i1.89cmxyl26000x40150,a类截面,查表得0.941xi65.7xxl26000y138150,b类截面,查表得0.353yi18.9yyNAf0.3532610215198086N198.1KN。(2)改用Q345钢时,设计承载力是否显著提高?34540,a类截面,按4048查表得0.921xx235x345138,b类截面,按138164查表得0.265yy235yNAf0.2652610310214411N214.4KN,承载力无太明显的提高。(3)如果轴心压力为330KN(设计值),I16能否满足要求?如不满足,从构造上采取什么措施就能满足要求?8距uuuuuuuuuuuujuu因为N300KN198.1KN,所以整体稳定不满足。-可编辑修改- 。在侧向加一支撑,重新计算。l2600/20y69150,b类截面,查表得0.757yi18.9yyNAf0.7572610215424791N424.8KN300KN,整体稳定满足。4.6设某工业平台柱承受轴心压力5000KN(设计值),柱高8m,两端铰接。要求设计一H型钢或焊接工字形截面柱。解:H型钢柱(1)初选截面设600.807(b类)N5000103l8000则A28961mm2289.61cm2,ii0133mm,f0.807215xy60选HW4284072035,其面积A361.4mm2,i18.2cm,i10.4cmxy(2)验算l80000x44150,b类截面,查表得0.882xi182xxl80000y77150,b类截面,查表得0.707yi104yyN5000103195.7Mpaf205Mpa,整体稳定满足。A0.707361.4102焊接工字形(1)初选截面根据H型钢截面,初选焊接工字形截面,如图所示。(2)计算参数A4203224001834080mm211I(4204643184003)3.4109mm4,I23242033.95108mm4x12y12-可编辑修改- 。I3.4109I3.95108ix315.9mm,iy107.7mm4xA34080yA34080(2)整体稳定验算l80000x25150,b类截面,查表得0.953xi315.9xxl80000y74150,b类截面,查表得0.726yi107.7yyN5000103202.3Mpaf205Mpa,整体稳定满足。A0.72634080(3)局部稳定验算42018b26.28(100.174)17.4t32h400022.2(250.574)62,局部稳定满足。t18w4.7图4.40(a)、(b)所示两种截面(焰切边缘)的截面积相等,钢材均为Q235钢。当用作长度为10m的两端铰接轴心受压柱时,是否能安全承受设计荷载3200KN。解:计算(a)图截面(1)计算参数:A500202500824000mm2120I85003220500(250)21.435109mm4x1221I22050034.17108mm4y12I1.435109I4.17108ix244.5mm,iy131.8mm4xA24000yA24000(2)整体稳定验算l100000x41150,b类截面,查表得0.895xi244.5xxl100000y76150,b类截面,查表得0.714yi131.8yy-可编辑修改- 。N3200103186.7Mpaf205Mpa,整体稳定满足。A0.71424000(3)局部稳定验算5008b212.3(100.176)17.6t20h500062.5(250.576)63,局部稳定满足。t8w计算(b)图截面(1)计算参数:A24000mm2125I104003225400(200)26.564108mm4x1221I22540032.67108mm4y12I9.564108I2.67108ix199.6mm,iy105.5mm4xA24000yA24000(2)整体稳定验算l100000x50150,b类截面,查表得0.856xi199.6xxl100000y95150,b类截面,查表得0.588yi105.5yyN3200103226.8Mpaf205Mpa,整体稳定不满足。A0.58824000(3)局部稳定验算40010b27.8(100.195)19.5t25h400040(250.595)72.5,局部稳定满足。t10w4.8设计由两槽钢组成的缀板柱,柱长7.5m,两端铰接,设计轴心压力为1500KN,钢材为Q235B,截面无削弱。解:(1)初选截面:设700.751(b类)yN1500103则A9289mm292.89cm2,f0.751215y-可编辑修改- 。选2[32a,,其面积A48.50297cm2,i12.44cmy(2)验算实轴的整体稳定l75000y60150,b类截面,查表得0.807yi124.4yyN1500103191.6Mpaf215Mpa,绕实轴的整体稳定满足。A0.80797102y(3)确定柱宽l7500设302260230252i0x144.2mm,1xy1x52xi144.2bx327.7mm取b=330mm,如下图所示。0.440.44(4)验算虚轴的整体稳定z2.24cm,I304.7cm4,i2.51cm011截面对虚轴的参数:255.2I2[304.748.50()2]16402cm41.64107mm4x2I1.64107l7500ix130mm,0x58,xA48502xi133x1302258230265[]1500.780oxx1xN1500103198.3Mpaf215Mpa,绕虚轴的整体稳定满足。A0.78097102x(5)缀板的设计li302.5175.3cm753mm0111选用缀板尺寸为-2601808,则ll180753180933mm,取l930mm,1011-可编辑修改- 。I304.7104分支线刚度k13276mm31l9301I11缀板线刚度kb(818032)30470mm3ba255.212k30470则b9.36k32671Aff97102215横向剪力Vy24535N852358524535930Vl2T1144705Na255.224535930aVl2MT115.704106Nmm222取焊脚尺寸h8mm,采用绕角焊,则焊缝计算长度为l180mmfw4470565.704106验算焊缝:44.4Mpa,188.6Mpaf0.78180f0.781802188.6(f)22()244.42160Mpafw160Mpa1.22f1.22f6.1有一两端铰接长度为4m的偏心受压柱,用Q235的HN400×200×8×13做成,压力设计值为490kN,两端偏心距相同,皆为20cm。试验算其承载力。解(1)截面的几何特征:查附表7.2A83.37cm2,I22775cm4,I1735cm4xyW1139cm3,i16.53cm;i4.56cm1xxy(2)强度验算:NMxArWnxnx4901034902010483.371021.051139103140.7Nmm2f215Nmm2(3)验算弯矩作用平面内的稳定:-可编辑修改- 。400024.2150x16.5310b/h=200/400=0.5<0.8,查表4.3得:对x轴为a类,y轴为b类。0.9736查附表4.1得:x1.0构件为两端支撑,有端弯矩且端弯矩相等而无横向荷载,故mx2EANEX1.12x220600083.371021.124.2226312kNNMmxxANxrW10.8x1xNEX4901030.973683.371021.0490201044901.05113910310.826312143.6Nmm2f215N/mm2(4)验算弯矩作用平面外的稳定:40087.7150y4.560.6368查附表4.2得:y-可编辑修改- 。287.721.07y1.070.8952b4400044000对y轴,支撑与荷载条件等与对x轴相同故:1.0,1.0txNMtxxAWyb1x4901031.01.0490201040.636883.371020.89521139103188.4Nmm2f215Nmm2由以上计算知,此压弯构件是由弯矩作用平面外的稳定控制设计的。轧制型钢可不验算局部稳定。6.2图6.25所示悬臂柱,承受偏心距为25cm的设计压力1600kN。在弯矩作用平面外有支撑体系对柱上端形成支点[图6.25(b)],要求选定热轧H型钢或焊接工字型截面,材料为Q235(注:当选用焊接工字型截面时,可试用翼缘2—400×20,焰切边,腹板—460×12)。240020解:设采用焊接工字型截面,翼缘焰切边,腹板—460×12,(1)截面的几何特征,A2402461.2215.2cm21I404463401.2463x12101946cm31I2240321333cm4y12101946W4078cm3x25-可编辑修改- 。I101946ix21.77cmxA215.2I21333iy9.96cmyA215.2(2)验算强度:b20062359.713因为:t20f,故可以考虑y截面塑性发展。M16000.25400kNmxNMxArWnx1x16001034.00106215.21021.054078103167.8Nmm2f205Nmm2(3)验算弯矩作用平面内的稳定:140064.3150x21.77查表4.3得:对x、y轴均为b类。0.784查附表4.2得:x-可编辑修改- 。2EA2206000215.2102NEX1.121.164.32x9611kN1.0对x轴为悬臂构件,故mx;NMmxxANxrW10.8x1xNEX16001030.784215.21021.040010616001.05407810310.89611202.6Nmm2f205N/mm2(4)弯矩作用平面外的稳定验算:70070.3150y9.960.749查附表4.2,y-可编辑修改- 。2f70.321.07y.y1.070.958b4400023544000构件对y轴为两端支撑,有端弯矩且端弯矩相等而无横向荷载,故取1.0,1.0txNMtxxAWyb1x16001031.01.04001060.749215.21020.9584078103201.5Nmm2f205Nmm2此压弯构件是由弯矩作用平面内的稳定控制设计的。(5)局部稳定验算NMhx.0maxAI2x16001034001064600215.21021019471042164.6Nmm2-可编辑修改- 。NMhx.0minAI2x1600103400106460215.210210947104216Nmm2(负号表示拉应力)164.616maxmin1.11.60164.6max由表6.3得:腹板:h235038.3160.52574.8t0fwyb20062359.71313翼缘:t20fy满足。6.3习题6.2中,如果弯矩作用平面外的支撑改为如图6.26所示,所选用截面需要如何调整才能适应?调整后柱截面面积可以减少多少?解:弯矩作用平面外的支撑间距减小一倍,因此可将原翼缘变窄,可选用翼缘236020,腹板500×12的焊接工字型截面。-可编辑修改- 。(1)截面几何特征A2362501.2204cm21I36543348503109892cm4x121I2236315552cm4y12109892W4070cm31x27I109892ix23.3cmxA204I1552iy8.7cmyA204强度验算:-可编辑修改- 。b18062358.713因为:t20f,故可以考虑截面塑性发y展。M16000.25400kNmxNMxArWnx1x16001034001062041021.054070103172Nmm2f205Nmm2(3)弯矩作用平面内的稳定验算:140060.30.8055x23.2,查附表4.2得x2EANEX1.12x22061032041031.160.3210359kN1.0对x轴为悬臂构件,故mx-可编辑修改- 。NMmxxANxrW10.8x1xNEX16001030.80552041021.040010616001.05407010310.810359204Nf205Nmm2mm2(4)弯矩作用面外的稳定验算:因上半段和下半段支撑条件和荷载条件一致,故:35040.1150y8.730.8986查附表4.2得y240.121.07y1.071.0b4400044000构件对y轴无论是上半段、还是下半段均为两端支撑,在弯矩作用平面内有端弯矩且端弯矩1.01.0相等而无横向荷载,故,tx-可编辑修改- 。NMtxxAWyb1x16001031.01.04001060.89862041021.04070103186Nmm2f205Nmm2(5)局部稳定验算:NMhx.0maxAI2x1600103400106500204102109891042169.4Nmm2NMhx.0minAI2x160010340010625020410210989210412.6N/mm2(负号表示为拉应力)-可编辑修改- 。182maxmin1.11.60169.4max腹板:h500041.7t12w2351620.525172.8xfyb18062358.71313翼缘:t20fy满足截面面积减少了:A215.220411.2cm2240018(选用翼缘,腹板500×10的焊接工字型截面也可满足要求。面积才194cm2、更省。)6.4已知某厂房柱的下柱截面和缀条布置如图6.27所示,柱的计算长度l=29.3m,0xl=18.2m,钢材为Q235钢,最大设计内力为N=2800kN,M=±2300kN•m,试验算此柱是否0yx安全。解:-可编辑修改- 。截面几何特征:分肢1(2):AA155cm2,i3.32cm,i24.7cm12xyI1702cm4,I94004cm4xyA2A310cm2整截面:11750yy875mm87.5cm122I2172015587.522376842cm4xI2376842ix87.56cmxA310(2)斜缀条的稳定:由于型钢I63a的翼缘厚度为22mm>16mm;-可编辑修改- 。f205N/mm2故假想剪力AffVy8523531010220523574.8kN85235tan1;450缀条内力及长度:74.8N52.9kNc2cos4501751752l247.5cmcos450212510A24.37cm2缀条采用∟,单角钢i2.48cmimin,min为斜平面,故杆件计算长度为0.9l。即:247.50.989.81502.48根据表4.3,截面为b类,0.62查附表4.2得:单角钢单面连接的设计强度折减系数为:0.60.00150.60.001589.80.735验算缀条稳定:-可编辑修改- 。N52.910335Nc2mm2A0.6224.37100.735215158Nmm2(3)横缀条稳定:(由于横缀条截面与斜缀条一样,可不验算。)l175cm;1750.963.5150222.480.7885查附表4.2得:20.60.001520.60.001563.50.695174.8103N2c19.5Nmm2A0.788524.3710220.695215149Nmm2符合要求(4)验算弯矩作用面内的整体稳定:l29300x33.5xi87.56x换算长细比:-可编辑修改- 。A2270xxA131033.522736224.371500.914查附表4.2得x2EANEX1.120x220600031010244211kN1.13621.0假设是有侧移结构:mxI2376842Wx26964cm31xy87.50.651-可编辑修改- 。NMmxxANxW11xxNEX28001030.9143101021.0230010628002696410310.91444211189Nmm2f205Nmm2(4)验算分肢的稳定:12300N28002714kN最大压力121.75b/h=176/630<0.8,查表4.3得:对y轴为a类,x轴为b类。175152.7150x13.320.8435查附表4.2得:x182073.7150y224.7-可编辑修改- 。0.8198查附表4.1得:yN2714103A0.8198155102min1213.6Nmm2f205Nmm2但(213.6-205)/205=4.2%分肢稳定基本满足由于分肢为热轧型钢,故无局部稳定问题。可以认为此柱安全。6.7图6.29的天窗架侧柱AB,承受轴心压力的设计值为85.8kN,风荷载的设计值w=±2.87kN/m(正号为压力,负号为吸力),计算长度l=l=3.5m,l=3.0m。要求选出双角0x0y钢截面。材料为Q235钢。100638解:选用∟,长肢相连,净距a=6mm。(1)截面几何特征:A212.625.2cm2;i3.18cmxi2.53cm;y3.32cmy1;Ii2A3.18225.2255cm4xx-可编辑修改- 。Ii2A2.53225.2161cm4yyI255Wx76.8cm31xy3.32;1I255Wx38.2cm32xy103.322(2)强度验算:1.05;1.2查表5.1,x1x21M2.873.524.39kNmx8MM由于x可正、可负,故由x产生的应力可使翼缘压应力增大(或减少)、也可使腹板压应力增大(或减少)。即:NM85.81034.39106xArW25.21021.0576.8103x11x34.0554.4588.5N/mm220.4N/mm2215N/mm2-可编辑修改- 。NM85.81034.39106xArW25.21021.238.2103x22x34.0595.77129.8N/mm261.72N/mm2215N/mm2所以,强度满足要求且腹板边缘起控制作用。(3)弯矩作用平面内稳定验算:350110150x3.180.493查附表4.2得:x2EANEX1.12X220600025.21021.11102385kN1.0有端弯矩和横向荷载共同作用且产生同向曲率,故mx。由前可知,腹板起控制作用,所以:-可编辑修改- 。NMmxxANxrW10.8x22xNEX85.81031.04.391060.493252085.81.238.210310.838569.06116.55185.6f215Nmm2还应验算腹板是否可能拉屈:NMmxxANW11.25x22xNEX85.81031.04.39106252085.81.238.210311.2538534.05123.7589.7N/mm2215N/mm2(4)验算弯矩作用平面外的稳定:-可编辑修改- 。300118.6150y2.53绕对称轴的长细比应取计入扭转效应的换算长细比yz,可采用简化计算方法确定:根据教材85页,有:b/t63/81.87520.48l/b0.483000/6322.860y2因此:1.09b41lt2yzy220y1.09634118.613000282122.10.4265属于b类截面,查附表4.2得:y①弯矩使翼缘受压时:10.0017f/235byy10.0017118.6235/2350.798-可编辑修改- 。1.0,1.0与对x轴相同,取txNMtxxAWyb1x85.81031.04.391061.00.426525200.79877103151.3Nmm2f215Nmm2②弯矩使翼缘受拉时:由于腹板的宽厚比ht100/812.518235/f0wy;故:10.0005f/235byy10.0005118.6235/2350.9411.0,1.0与对x轴相同,取txNMtxxAWyb2x85.81031.04.391061.00.426525200.94138.2103202Nmm2f215Nmm2-可编辑修改- 。轧制型钢可不验算局部稳定。100807100638故:选用∟合适。(也可选用∟,更省)5.1一平台的梁格布置如图5.53所示,铺板为预制钢筋混凝土板,焊于次梁上,设平台恒荷载的标准值(不包括梁自重)为2.0kN/m2,活荷载的标准值为20kN/m2。试选择次梁截面,钢材为Q345钢。解:平台板与次梁连牢,所以不必计算整体稳定。1kNm假设次梁自重为,次梁间距为3m,故次梁承受的线荷载标准值为:q2.03120367kNm67Nmmk线荷载设计值为:[可以判定是活载起控制作用,故恒载分项系数为1.2,活载分项系数为1.3]:q2.0311.22031.386.4kNm最大弯矩设计值:11Mql286.462388.8kNmx88根据抗弯强度选择截面,需要的截面模量为:WM/(rf)nxxx388.8106/(1.05310)1194cm3446199812W1217cm3选用HN,x验算强度:WW1194cm3跨中无孔眼削弱,此nx大于nx。由于型钢的腹板较厚,一般不必验算抗剪强度;若将次梁连于主梁的加劲肋上也不必验算次梁支座处的局部承压强度。I27146cm465.10.651kNm其他截面特性:X,自重㎏/m=,小于假设自重,不必重新计算抗弯强度。由附表2,验算刚度:q2.030.651203k66.651kNm66.651Nmm在全部荷载标准值作用下:-可编辑修改- 。v5ql3566.65160003Tkl384EI38420610327100104x1v1T294l250在可变荷载标准值作用下:v12031v1QQl29466.651323l3005.3图5.54(a)所示的简支梁,其截面为不对称工字型[图5.54(b)],材料为Q235-B钢;梁的中点和两端均有侧向支撑;在集中荷载(未包括梁自重)F=160kN(设计值)的作用下,梁能否保证稳定性?解:该简支梁的稳定性系数b应按附3.1计算4320Aht2235.1y1bb2W4.4hbfyxyl6m该梁的跨度中点有侧向支撑1,且主要承受集中荷载的作用,查附表3.1,得1.75b;1I1303800.831103y122336.8cm4A301101800.8104cm2I2336.8iy4.74cmyA104-可编辑修改- 。l6001126.6yi4.74yI1bII1211303120.96411130311031212截面不对称影响系数b(加强受压翼缘)0.821bb0.820.96410.7424求形心,设形心到上翼缘外边缘的距离为d,则:3010.5800.84110181.5104dd33.2cm-可编辑修改- 。1I3013301d0.52x1210.8803800.841d2121101310181d0.521293440cm4I93440Wx2810cm3上翼缘:x1d33.2下翼缘:I93440WX1914.8cm3Wx282d48.8x1-可编辑修改- 。4320Aht235.1y1bb2W4.4hbfyx1y4320104821.75126.622810126.61223510.74244.4822352.50.60.282由1.07得:bb0.2821.070.9571.0b2.5梁单位长度自重标准值(钢材重量集度为77kN/m3):qA771041040.8kNmk11Mql2Flx84110.81.21221601284497.3kNm-可编辑修改- 。M497.3106x184.9N/mm20.9572810103Wbx1f215Nmm2故梁可以保证其整体稳定性。讨论:本题只要求验算整体稳定性,但由于是加强受压翼缘,从截面强度方面考虑,有可能在整体失稳前受拉翼缘先拉屈服,故还应计算受拉翼缘的拉应力:M497.3106x247.3N/mm2W1.051914.8103xx2f215Nmm2故截面强度不满足要求。5.4设计习题5.1的中间主梁(焊接组合梁),包括选择截面、计算翼缘焊缝、确定腹板加劲肋的间距。钢材为Q345钢,E50焊条(手工焊)。解:次梁所传的集中荷载标准值为F2.030.65162036400kNk设计值为:-可编辑修改- 。F2.030.65161.220361.3516kN3.5kNm假设主梁自重标准值为,则设计值为1.23.54.2kNm支座边缘处最大剪力为:1VR5162.54.21812129037.81327.8kN跨中最大弯矩:1M1327.89516634.292max211950.24644170.17136kNmt16mm采用焊接组合梁,估计翼缘板厚度f,故抗弯强度设计值为f295Nmm2需要的截面模量为:M7136106Wx23038103mm3xf1.05295(1)试选截面:vl1400按刚度条件,梁的最小高度(T):-可编辑修改- 。fl2hmin1.34106vT295400180001585mm1.34106梁的经济高度:h2W0.42(23038103)0.41762mmsx取梁的腹板高度:hh1800mmw0按抗剪要求的腹板厚度:f180Nmm2抗剪强度设计值为vV1327.8103t1.2max1.25.21mmwhf1800170wvh1800tw12.1mm按经验公式w3.53.5t10mm考虑腹板屈曲后强度,取腹板厚度w,每个翼缘所需截面积:WthAxwwfh6w23038103101800180061279930009799mm2翼缘宽度:-可编辑修改- 。hh18001800b~~360~600mmf5353b420mm取fA9799tf23.3mm翼缘厚度:fb420ft25mm取f翼缘外伸宽度与厚度之比:b2058.21323510.73t25fy满足局部稳定要求且可以考虑截面塑性发展。截面如图:42025xx180010为施工方便,不沿梁长改变截面。(2)强度计算:1I4218534118032234688cm4x12I2223468Wx24159cm3xh1852A18012422.5390cm2-可编辑修改- 。kgm3kNm3由钢材质量密度为7850,重量密度为77,得梁的自重:g390104773kNmk考虑腹板加劲肋增加的质量,原假设的梁自重3.5kN比较合适。WW验算抗弯强度(无孔眼nxx):M7136106x281.3Nmm2rW1.0524159103xnxf295Nmm2验算抗剪强度:VS1327.8103maxIt223468810410xw42025912.5900104500.0000059419581250405000081N/mm2f180Nmm2v0主梁的支承处以及支承次梁处均配置支承加劲肋,故不验算局部承压强度c验算跨中截面翼缘与腹板交界处的折算应力:V1327.825164.29258kN3-可编辑修改- 。VSmax33Itxw1327.810342025912.522346881041056.9N/mm2y9003281.3273.7Nmm23y925232273.72356.92red33290.9Nmm21.1f(3)梁的整体稳定验算:次梁可视为受压翼缘的侧向支承,主梁受压翼缘的自由长度与宽度之比:l23513007.11613.2b423451不需要验算主梁的整体稳定性(4)刚度验算:vl由附表2.1,挠度容许值T400(全部荷载标准值作用)或vlQ500(仅有可变荷载标准值作用)。全部荷载标准值在梁跨中产生的最大弯矩:R4002.53.51821031.5kNk-可编辑修改- 。1M1031.59400633.592R25541.75kNmvMl5541.7510618000Tkl10EI102060002234688104x11vT461.5400l可变荷载标准值在梁跨中产生的最大弯矩:R20362.5900kNkM9009203663R4860kNmv148601v1QQl461.55541.75526.2l500(5)翼缘和腹板的连接焊缝计算:翼缘和腹板之间采用焊缝连接VSh1f1.4Ifwxf1327.842025912.51032.03mm1.42234688104200-可编辑修改- 。h8mm1.5t1.5257.5mmfmax取1.2t1.21012mmmin(6)主梁加劲肋设计:1)各板段强度验算该腹板考虑屈曲后强度,应在支座处和每个次梁处(5个固定集中荷载处)设置支承加a650mm劲肋,端部板段采用如下图构造,另加横向加劲肋,使。1a16501因h18000htf0wys4145.34180065022351801.210.790.8416.7fIH故若crv,即板段1范围内不会屈曲,支座加劲肋就不会受到水平t的作用。对板段I:左侧截面剪力:V1327.84.20.651325.1kN1相应弯矩:1M1327.80.654.20.652862.2kNm12-可编辑修改- 。因M862.2kNm1M4202518252955653kNmfVV故用1u验算,ah(3000650)/180010:htf0wys415.344ha22350180010345235415.3441800235021.921.2htfV0wvu1.2s1800101801.921.21481kNV1325.1kN1满足要求。右侧截面剪力:V1327.84.231315.2kN2相应弯矩:1M1327.834.2323964.5kNm22-可编辑修改- 。M3964.5kNmM5653kNm因2f,VV1481kN且2u,满足要求。对板段III,验算右侧截面:htf0wys2225415.344ha01800103452352415.344180030002.041.2htfV0wvu1.2s1800101802.041.21377.2kNV258kN30.5V0.51377.2688.6kNuMMM故用3maxeu验算:-可编辑修改- 。h01800tf10345wyb1532351532351.431.250.210.6bb(1)h3t1cwe2Ix(10.603)9003101222346881040.935MrWfeuxex1.050.935241591032956996.8kNmM7136kNmmax但相差:(7136-6996.8)/7136=1.95%,基本满足。对板II可不进行验算。2)加劲肋计算横向加劲肋的截面h1800b04040100mm宽度:s3030b130mm取s-可编辑修改- 。b130ts8.7mm厚度:s1515t10mm取s中部承受次梁支座反力的支承加劲肋的截面验算:2.041.2由上可知:s1.1f1.118047.6Nv2.04cr22mm2s故该加劲肋所承受轴心力为:NVhtFsucrww1377.210347.61800105161031036.4kN以轴心受压计算支承加劲肋以及每侧各15t235123.8fwy故截面面积:A2130102123.810s5076mm21I1027031640104mm4z12I4iz16041056.84mmzA5076f180031.7y38.4z56.84z235-可编辑修改- 。0.905查b类:z验算腹板平面外稳定:N1036.4103s225.6N/mm2A0.9055076zSf310N/mm2因为采用次梁连于主梁加劲肋的构造可不验算加劲端部的承压强度。13010靠近支座加劲肋也用—截面,不必验算。R1327.8kN支座加劲肋的验算:支反力,还应加上边部次梁直接传给主梁的支反力:F258kN2218014采用板,主梁的支承长度为250mm,A2180142123.810s7516mm21I1437035910104mm4z12Iiz5910104751688.7mmzAsf180088.720.3y24.6zz2350.955查b类:z验算腹板平面外稳定:-可编辑修改- 。N1327.8258103s220.9Nmm2A0.9557516zSf310Nmm2验算端部承压:1327.8258103404.5Nmm2ce21418040f400Nmm2计算加劲肋与腹板的连接焊接(按侧面角焊缝计算,将次梁支座反力增大30%):设焊脚尺寸为6mm1327.82581031.3hf40.7180026026200用2.2mm6mm1.5t1.5145.6mm1.2t12mm合适w-可编辑修改- 。5.5根据习题5.1和习题5.4所给定条件和所选定的主、次梁截面,设计次梁与主梁连接(用等高的平接,并按1:10比例尺绘制连接构造图。解:如图,布置10.9级M22的摩擦型高强度螺栓一排,摩擦面作喷砂处理,0.5。边距:65mm1.5d1.52436mm04d42496mm或8t8972mm0符合表3.4的构造要求。Nb0.9nPvf0.910.519085.5kN次梁的支反力为:F2.030.6511.22031.33258kN考虑到连接处有一定的约束作用,并非理想铰接,因此螺栓除了轴心力以外还受扭矩作用。简化计算时,通常将次梁的支座反力值加大20%~30%进行连接计算。故所需要的螺栓数:1.2~1.3F/Nb1.2~1.3258/85.5v3.62~3.92取4个螺栓,最小中心间距为:3d=3×24=72mm,最小端距为:2d=2×24=48mm。00次梁的腹板高度:446-2×20=406mm>2×48+3×72=312mm,足够布置4个螺栓。h6mm加劲肋的稳定5.4已经计算,焊缝按构造要求取f即可。-可编辑修改- 。若取10.9级M20的摩擦型高强度螺栓一排则需布置5个螺栓。-可编辑修改- 。欢迎您的下载,资料仅供参考!致力为企业和个人提供合同协议,策划案计划书,学习课件等等打造全网一站式需求-可编辑修改-
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