西科大27米钢屋架设计

1、钢结构课程设计班级:姓名:学号:指导老师:2021年12月30日一、设计资料1、题号39条件：梯形钢屋架跨度27ml长度102ml柱距6m该车间内设有两台200/50kN中级工作制吊车,轨顶标高为8.000m.冬季最低温度为-20C,地震设计烈度为7度,设计根本地震加速度为0.1g.采用1.5mx6m预应力混凝土大型屋面板,80mm厚泡沫混凝土保温层,卷材屋面,屋面坡度i=1/10.屋面活荷载标准值为0.7kN/m2,雪荷载标准值为0.1kN/m2,积灰荷载标准值为0.6kN/m2屋架较支在钢筋混凝土柱上,上柱截面为400mnm5553600.7213942=39.42cm2,ix4cm,25

2、3940,查表得y0.721,195.4MPa215MPaiy3.39cmloyiy253974.933.963.5,y故所选截面适宜.Ncf193.41kN,NfG148.65kN再分式桁架中的斜腹杆,在桁架平面内的计算长度取节点中央间距lox2087mm,在桁架平面外的计算长度:,ccN2、,小 CC10y11(0.750.252)4174(0.750.25选用2L80X7,查角钢规格表得由于yx,只需求X.查表X=0.524,那么:再分腹杆截面如图:5.竖杆Hd148.65193.41)3932.6mmA=21.72cm2,iyx2.46cm,iy3.75cmloxxT-ix208724

3、.681.8150,loy3932.104.915037.5NyA1934100.5242172164.3MPa215MPaN82.89kN,lox0.8l0.830502440mm,10y3050mm由于杆件内力较小,ilo2440150loy3050一20.3mm150150选择,需要的回转半径为16.3mm,iy查型钢表,选截面的ix和iy较上述计算的ix和iy略大些.选用2L63X5,其几何特性为：A=12.29cm2,ix1.94cm,iy3.04cm由于loxix244019.4125.8150,loy305030.4100.3150 x,只需求x.查表x=0.406,那么:中央竖

4、杆截面如图:其余各杆件的截面选择结果见表3.82890 xA0.4061229166.1MPa215MPa图10:竖杆截面名称杆件编P内力/kN计算长度/cm截面规格截回卸积/一2/cm回转半径/cm长细比容许长细比稳定系数计算应力N人(Nmm2)IOXl0yixiyXyXy上弦HI、IJ-1059.33150.8452.41|180X110X1267.423.088.754951.71500.849185.06下弦cd1007.944501335IL160X100X1050.632.857.78157.9171.63500.246161.6腹杆aB-555.362532531|125X80X

5、1039.4243.3963.574.91500.721195.4Bb439.32262.2262.2H100X1038.523.054.6085.957.01500.648176bD-357.53287.3287.3II100X1038.523.054.6094.262.51500.594156.3Dc254.75287.3287.31100X1038.523.054.6094.262.51500.594111.3cf-193.41208.7393.3IT80X721.722.463.7581.8104.91500.524164.3fG-148.65208.7393.3II80X721.72

6、2.463.7581.8104.91500.524130.6Ef40.34189189II63X512.291.943.0497.462.21500.57557.1Gd-18.0155.18326.5326.5II90X621.272.794.1311779.11500.254102.1dg-45.0295.98224.9425.9II63X512.291.943.04115.9140.11500.341107.4gJ-41.25136.87224.9425.9163X512.291.943.04115.9140.11500.34198.4Hg37.02203.5203.5II63X512.2

7、91.943.04104.966.91500.52357.6竖杆Aa-27.63161.2201.5163X512.291.943.0483.166.31500.66833.7Cb-55.26184230II63X512.291.943.0494.875.71500.58876.5Ec-82.89208260II63X512.291.943.04107.285.51500.511132Ff-55.261041301163X512.291.943.0453.642.81500.83853.7Hd-82.89244305190X621.272.794.1387.573.81500.40696Ig-

8、55.26122152.51163X512.291.943.0462.950.21500.79156.8表3屋架杆件截面选择表六、节点设计采用E43焊条时,角焊缝的抗拉、抗压和抗剪强度设计值ffw=160Mpa(1)下弦节点b设bB杆的肢背和肢尖焊缝hf8mm和6mm,所需焊缝长度为：取L160mml2120mm1,0设bD杆的肢背和肢尖焊缝hf8mm和6mm,所需焊缝长度为:取L130mml2100mmCb杆的内力很小,焊缝尺寸可按构造确定,取hf5mm根据以上求得的焊缝长度,并考虑杆件之间的间隙以及制作、装配等误差,按比例作出节点详图(见图11),从而确定节点板的尺寸为340X475mm下

9、弦与节点板连接到焊缝长度为475mmhf5mm,焊缝承受节点左、右弦杆的内力差N=Nc-Nab=735.51-296.19=439.32kN.验算肢背焊缝的强度：肢背li:11K1N20.7hf1ffw0.65439.159.4mm肢尖l2：l2K2N20.7hf2fW0.35439.3210320.76160114.4mm肢背l1:l1KN20.7hf1fW0.653575310320.7816012968mm肢尖l2：12K2N20.7hf2fW_30353575310320.7616093.1mmf上.65439321d8773N/m吊160n吊f20.7hflw20.7547525图1

10、1：下弦节点“b(2)上弦节点“B斜中fBb与节点板连接焊缝计算,与下弦节点b中Bb杆计算相同.斜杆Ba与节点板连接焊缝计算：N=-555.36kN设“aB杆的肢背与肢尖的焊脚尺寸分别为10m而6mm所需焊缝长度为取11180mm12150mm.为了便于在上弦上搁置大型屋面板,上弦节点板的上边缘可缩进上弦肢背8mm用槽焊缝将上弦角钢和节点板连接起来.槽焊缝作为两条角焊缝计算,槽肢背li:11K1N20.7hf1ffw0.65555.3610320.710160161.2mm肢尖12：l2K2N20.7hf2ffw0.35555.3610320.76160144.6mm735L5WN焊缝强度设计

11、值乘以0.8的折减系数.计算时可略去屋架上弦坡度的影响,而假定集中荷载P与上弦垂直.上弦肢背槽焊缝内的应力由下面计算得到:1hf11节点板厚实度2-126mm,hf26mm.肢尖焊缝承当弦杆内力N55O94kN,肢背采用塞焊缝,承受节点荷载F55.26kN.上弦与节点板间焊缝长度为460mm那么0.6555094020.76(46012)节点如图:(3)屋脊节点J弦杆一般用与上弦杆同号角钢进行拼接,为使拼接角钢与弦杆之间能够密合,并便于施焊,需将拼接角钢进行切肢、切棱.拼接角钢的这局部削弱可以靠节点板来补偿.拼接一侧的焊缝长度可按弦杆内力计算.95.2MPa552600.76(46012)14

12、.7MPa小(岩)295.2296MPa160MPaN=-1059.33kN.设肢尖、肢背焊脚尺寸为10mm那么需焊缝长度为拼接角钢的长度ls2lw2hf弦杆杆端空隙,拼接角钢长度取540mm上弦与节点板间的槽焊,假定承受节点荷载,验算略.上弦肢尖与节点板的连接焊缝,应按上弦内力的15刈算.设月J尖焊缝hf10mm,节点板长度为500mm节点一侧弦杆焊缝的计算长度为lw(500/21020)220mm焊缝应力为:0710220点设置工地拼接,左半边的上弦、斜杆和竖杆与节点板连接用工厂焊缝,而右半边的上弦、斜杆与节点板的连接用工地焊缝.节点形式如图：105933040.

13、710160236.5mm51.6MPa601220.7102202109.9MPa160MPa109.9)2:1.2251.62103.8MPa160MPa因屋架的跨度很大,需将屋架分为两个运输单元,在屋脊节点和下弦跨中节Mf2502504、支座节点“a为了便于施焊,下弦杆角钢水平肢的底面与支座底板的净距离取160mm在节点中央线上设置加劲肋,加劲肋的高度与节点板的高度相等,厚度14mm(1)支座底板的计算支座反力：R552600N设支座底板的平面尺寸采用280mm360mm,如仅考虑有加劲肋局部的弯矩为:式中：一底板下的平均应力,即=6.58MPa02系数,由b2

14、/a2查表确定.b2为两边支承的相交点到对角线a2的垂直距离.由此得:150133b99.2b299.2mm产0.49201.1a2201.1的抗压强度:R5526006.58MPaAn84000fc9.6MPacfc支座底板的厚度按屋架反力作用下的弯矩计算,节点板和加劲肋将底板分为每块板的单位宽度的最大14221(140)215022201.1mm底板承受支座反力,那么承压面积为28030084000mm2.验算柱顶混凝土式中：fc混凝土强度设计值,对C20混凝土,9.6MPa.四块,每块板为两相邻边支承而另两相邻边自由的板,a2两边支承之间的对角线长度,即a2查表得2=0.0586.那么单

15、位宽度的最大弯矩为:0.05866.58201.1215578.14Nmm底板厚度:所以底板尺寸为28030022mm(2)加劲肋与节点板的连接焊缝计算加劲肋与节点板的连接焊缝计算与牛腿焊缝相似(图13).偏于平安的假定一个加劲肋的受力为屋架支座反力的四分之一,那么焊缝内力为R/4138150N,节点板传递R/2276300N节点板与底板的连接焊缝长度lw2(28012)536mm,所需焊脚尺寸615578.1421520.85mm,取t=22mmR552600V138150N,M44Ve138150658979750Nmm为:13815020.76419689797501.2220.764192=49.37M