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普通钢屋架设计计算书一、教学要求1.了解普通钢屋架设计的全过程;2.学习结构施工图的绘制和结构计算书的编制方法3.了解钢屋盖支撑体系的作用并能正确布置支撑;4.掌握钢屋架的内力计算、杆件截面选择,节点设计的方法;5.掌握焊接连接的构造要求。二、屋架形式及主要尺寸的确定(学号为306,跨度为30m,端部高度为1.95m,坡度为1/11)图一桁架形式及几何尺寸三、支撑布置根据车间长度,屋架跨度,荷载情况,以及吊车设置情况,宜布置三道上、下弦横向水平支撑,垂直支撑和系杆,屋脊节点及屋架支座处沿厂房通长设置刚性系杆,屋架下弦沿跨中通长设一道柔性系杆。构件编号采用汉语拼音字母,凡与支撑连接的屋架可编号为WJ1,其它编均为WJ2,屋架垂直支撑:CC1、CC2…,屋架上弦水平支撑:SC1、SC2…,屋架下弦水平支撑:XC1、XC2…,刚性系杆:GG1、GG2…,柔性系杆:LG1、LG2…。图二桁架支撑布置四、屋架内力计算1.计算的基本假定节点均为铰接:所有杆线的轴线均位于同一平面内,且同心交汇与节点;荷载均作用于结点。2.荷载计算屋面活荷载与雪载一般不会同时出现,由荷载条件知,基本雪压大于屋面活荷载,基本风压不考虑。沿屋面斜面分布的永久荷载应乘以1/cos=004.111/1112换算为沿水平投影面分布的荷载。桁架沿水平投影面积分布的自重(包括支撑)按经验公式(PW=0.12+0.011跨度)计算,跨度单位为m。标准永久荷载:预应力混凝土大型屋面板2/406.140.1004.1mkN改性沥青防水层1.0042/402.040.0mkN20厚1:2.5水泥砂浆找平层1.0042/402.040.0mkN80厚加气混凝土保温层1.0052/482.048.0mkN屋架和支撑自重为0.12+0.0112/450.030mkN共3.2422/mkN标准可变荷载:2/70.0mkN屋面活荷载3.荷载组合考虑三种组合:(1)全跨永久荷载+全跨可变荷载(按永久效应控制)全跨节点荷载设计值:F=(1.3556.4565.1)7.04.1242.3KN(2)全跨永久荷载+半跨可变荷载全跨节点永久荷载设计值:对结构不利时:F1.1=1.35kN39.3965.1242.3(按永久荷载为主的组合)FkN01.3565.1242.32.12.1(按可变荷载为主的组合)对结构有利时:F65.1247.30.13.1=29.18kN半跨节点可变荷载设计值:FkN17.665.1)7.07.0(4.11.2(按永久荷载为主的组合)FkN82.865.17.04.12.2(按可变荷载为主的组合)(3)全跨桁架包括支撑+半跨屋面自重+半跨屋面基本雪压(按可变荷载为主的组合)全跨节点桁架自重设计值:对结构不利时:FkN86.465.145.02.11.3对结构有利时:FkN05.465.145.00.12.3半跨节点屋面板自重及雪压设计值:FkN94.2365.1)7.04.140.12.1(4(1)、(2)为使用阶段荷载情况,(3)为施工阶段荷载情况。计算详图如图三。图三桁架计算简图桁架杆件内内力表杆件名称内力系数(F=1)第一种组合F×①第二种组合第三种组合计算杆件内力/kN全跨①左半跨②右半跨③F1,i×①+F2,i×②F1,i×①+F2,i×③F3,i×①+F4×②F3,i×①+F4×③上弦ABBC、CDDE、EFFG、GHHIIJ、JK0-11.67-18.95-22.57-23.53-24.030-8.76-13.64-15.33-14.72-15.220-3.235.91-8.04-9.79-9.790-531.69-863.36-1028.29-1072.03-1094.8100000-531.69-863.36-1028.29-1072.03-1094.81下弦abbccddeef6.7616.0521.1623.2622.405.1611.8014.8115.2312.321.784.727.058.9511.20307.98731.24964.051059.731020.54307.98731.24964.051059.731020.54斜腹杆aBBbbDDccFFddHHeEg-11.668.88-7.775.54-4.392.77-1.620.391.56-8.906.51-5.373.49-2.330.960.17-1.233.50-3.072.63-2.662.28-2.282.00-2.001.79-2.16-531.23404.57-354.00252.40-200.00126.20-73.8117.7771.07-62.760.5385.49-76.1526.4048.122.49-27.8791.37-55.7544.75-45.39-531.23404.57-354.00252.40-200.00126.20-76.152.49-27.8744.75-45.3985.49gKgI2.290.674.240.67-2.160104.3330.53116.3630.5376.87112.64-42.44-42.44116.3630.53竖杆AaCb、EcGd、JgIeKf-0.5-1-1-1.50-0.5-1-1-1.5000000-22.78-45.56-45.56-68.340-22.78-45.56-45.56-68.340五.杆件设计(1)上弦杆整个上弦杆采用等截面,按HI、IJ杆件的最大内力设计。N=-1094.81kN上弦杆计算长度:在桁架平面内,为节间轴线长度:cmlx6.1500在桁架平面外,根据支撑布置和内力变化情况,取:cmly8.4516.15030因为xyll003,故截面宜选用两个不等肢角钢,短肢相并。又腹杆最大内力为N=531.23kN,查表得,节点板厚度选用12mm,支座节点板厚度选用14mm。设60,查附录得0.807。则20.6310215807.01094810mmfNAreqcmlixx51.2606.1500,cmliyy53.7608.4510根据需要的yxiiA、、查角钢规格表,选用2∟12110180A=67422mm,cmix11.3cmiy76.8,1512/180/1tb按所选的角钢进行验算:42.4811.36.1500xxxil06.14188.45156.056.015/01bltby15045.581807.521245181121807.37.5217.3422412201btltbyyz截面x和y平面皆属于b类,由于xyz,查表得8162y22/215/1996742816.01094810mmNmmNAN所选截面合适。(2)下弦杆整个下弦杆采用同一截面,按最大内力设计值计算:N=1059.73kNcmlx3000cmly14850249292151059730mmfNAreq选用2∟10110180,因xyll00,故用不等肢角钢,短肢相并A=56742mm5818.92mmcmix13.3cmiy71.835017071.8148500yyyil由后面支座节点设计可知,下弦有mm5.212的栓孔削弱,下弦净截面面积:25158125.2125674mmAn22/215/5.20551581059730mmNmmNANn(3)端斜杆aB杆件轴力:N=-531.23kN计算长度cmllyx5.24800采用不等肢角钢,长肢相并,使yxii。选用2∟1080120,A=39422mm,cmix98.3cmiy38.3,810/80/2tb44.6298.35.2480xxxil91.1480248548.048.08/202bltby15084.781024858009.1138.3248509.1122422042tlbyyyz因xyz,696.0y22/215/6.1933942696.0531230mmNmmNAN所选截面合适。(4)腹杆eg-gk此杆在g处不断开,采用通长杆件。最大拉力:Ngk=116.36KN,另一段Neg=85.49KN最大压力:Neg=45.39KN,另一段Ngk=42.44KN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心间距:xl0=223.5cm在桁架平面外计算长度:)25.075.0(1210NNlly=cm74.439)39.4544.4225.075.0(447选用2∟563A=1228.62mm,cmix94.1,cmiy04.3,6.125/63/1tb2.11594.15.2230xxxil4.36634.439756.056.06.12/01bltby1507.14654.43973.6475.0104.374.439475.0122422041tlbyyyz查表得320.0y22/215/5.1151229320.045390mmNmmNAN拉应力22/215/7.9412286116360mmNmmNAN(5).竖杆IeN=-68.34kNcmllx3.2431.3048.08.00cmlly1.3040取150cmlixxeq62.11503.2430cmliyyeq03.21501.3040选用2∟563A=1228.62mmcmix94.1cmiy04.36.125/63/1tb1504.12594.13.2430xxxil2863304156.056.06.12/01bltby1503.1035304163475.014.303041475.0122422041tlbyyyz查表得409.0x22/215/1366.1228409.068340mmNmmNAN(6).竖杆AaN=-22.78kNcmlx1950cmly1950选用2∟556,A=10842mmcmix72.1cmiy77.22.115/56/1tb1504.11372.11950xxxil2.205619556.056.02.11/01bltby1509.735195056475.0177.2195475.0122422041tlbyyyz查表得473.0x22/215/4.441084476.022780mmNmmNAN(7).腹杆CbN=-45.56kNcmlx8.1770cmly3.2220选用2∟550,A=960.62mmcmix53.1cmiy53.2105/50/1tb1502.11653.18.1770xxxil8.2553.22256.056.010/01bltby15098.8953.22250475.0153.23.222475.0122422041tlbyyyz查表得457.0x22/215/8.1036.960457.045560mmNmmNAN(8).腹杆bDN=-354kNcmlx7.2230cmly6.27
本文标题:钢结构课程设计梯形桁架跨度30米
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