钢结构课程设计梯形钢屋架计算书

1－、设计资料1、某工厂车间，采用梯形钢屋架无檩屋盖方案，厂房跨度取27m，长度为102m，柱距6m。采用1.5m×6m预应力钢筋混凝土大型屋面板，保温层、找平层及防水层自重标准值为1.3kN/m2。屋面活荷载标准值为0.5kN/m2，雪荷载标准值0.5kN/m2，积灰荷载标准值为0.6kN/m2，轴线处屋架端高为1.90m，屋面坡度为i=1/12，屋架铰接支承在钢筋混凝土柱上，上柱截面400mm×400mm，混凝土标号为C25。钢材采用Q235B级，焊条采用E43型。2、屋架计算跨度：Lo=27m－2×0.15m=26.7m3、跨中及端部高度：端部高度：h′=1900mm（端部轴线处），h=1915mm（端部计算处）。屋架中间高度h=3025mm。二、结构形式与布置屋架形式及几何尺寸如图一所示:2、荷载组合设计桁架时，应考虑以下三种组合：①全跨永久荷载+全跨可变荷载(按永久荷载为主控制的组合)：全跨节点荷载设计值：F=(1.35×3.12+1.4×0.7×0.5+1.4×0.9×0.6)×1.5×6=49.122kN图三桁架计算简图本设计采用程序计算结构在单位节点力作用下各杆件的内力系数，见表一。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全跨①左半跨②右半跨③F1×①+F2×②F1×①+F2×③F3×①+F4×②F3×①+F4×③内力（KN)上弦AB000000000BC，CD-10.82-8.15-2.67-531.50-551.36-456.42-227.16-109.78-551.36DE，EF-17.85-12.87-4.98-876.83-899.63-762.94-362.43-193.42-899.632四、杆件截面设计1、上弦杆：整个上弦杆采用相等截面，按最大设计内力IJ、JK计算，根据表得：N=-1139.63KN，屋架平面内计算长度为节间轴线长度，即：oxl=1355mm,本屋架为无檩体系，认为大型屋面板只起刚性系杆作用，不起支撑作用，根据支撑布置和内力变化情况，取屋架平面外计算长度oyl为支撑点间的距离，即：oyl=3oxl=4065mm。根据屋架平面外上弦杆的计算长度，上弦截面宜选用两个不等肢角钢，且短肢相并，如图四所示：图四上弦杆FG，GH-21.55-14.66-6.89-1058.58-1070.90-936.29-418.75-252.32-1070.90HJ-22.72-14.23-8.49-1116.05-1107.80-1008.36-415.23-292.28-1116.05IJ，JK-23.2-14.72-8.48-1139.63-1134.49-1026.38-428.05-294.39-1139.63下弦ab5.994.591.4294.24306.59251.32127.4359.10306.59bc14.7710.893.88725.53748.57627.12305.05154.89748.57cd19.9914.035.96981.951000.85861.04397.67224.811000.85de22.3414.647.71097.391100.50980.27422.16273.511100.50ef21.8612.049.821073.811037.26998.80364.14316.581073.81斜腹杆aB-11.23-8.6-2.63-551.64-574.70-471.27-238.79-110.91-574.7Bb8.996.622.37441.61455.48381.85185.4994.46455.48bD-7.71-5.37-2.34-378.73-385.31-332.81-152.50-87.59-385.31Dc5.853.742.11287.36286.56258.32108.5473.63287.36cF-4.59-2.52-2.07-225.47-217.66-209.86-76.29-66.65-225.47Fd3.11.211.89152.28138.48150.2640.9855.55152.28dH-1.92-0.07-1.85-94.31-74.00-104.83-10.83-48.96-104.83He0.67-1.021.6932.917.7354.68-18.5939.4654.68-18.59eg1.183.22-2.0457.96100.529.3974.71-37.96100.52-37.96gK1.913.95-2.0493.82140.8437.0693.89-34.41140.84-34.41gI0.670.67032.9137.0125.4017.613.2637.01竖杆Aa-0.5-0.50-24.56-27.62-18.95-13.14-2.43-27.62CbEc-1-10-49.12-55.23-37.91-26.28-4.86-55.23Gd-1-10-49.12-55.23-37.91-26.28-4.86-55.23Jg-1-10-49.12-55.23-37.91-26.28-4.86-55.23Ie-1.5-1.50-73.68-82.85-56.86-39.42-7.29-82.85Kf0000000003腹杆最大内力N=-574.7KN，查表可知，中间节点板厚度取12mm，支座节点板厚度取14mm。设=60，根据《规范》由双边角钢组成的T行和十字形截面均属于b类，查Q235钢轴心受力稳定系数表，=0.807，则需要截面积：233.6568215807.01063.1139mmfNA需要回转半径cmcmlioxx26.2605.135，cmlioyy78.6605.406根据A、xi、yi查角钢规格表，初选用2∟180×110×12，肢背间距a=12mm，该截面特性如下：A=67.422cm，xi=3.10cm，yi=8.75cm。1512/180/1tb按所选角钢进行验算：71.4310.3135.5oxxxil＜[]=150∵1512/180/1tb＞65.12180/406556.0/56.01bloy∴)1807.521240651(121807.3)7.521(7.342241221btltboyyz=57.89＜150截面在x和y平面皆属b类，由于yzx，只需求出y，查轴心受压杆稳定系数表得y＝0.819,则有:45.2066740819.01139630ANy＜2215Nmm所需截面合适。2、下弦杆:整个下弦杆采用同一截面，按最大设计值计算，根据表得杆de内力最大N=1100.50KN。计算长度又有:oxl=2700mm,yol=26700/2=13350mm。需要截面面积2219.51mm60.51182151100500NAcmf，选用2∟16010012，采用短肢相并，如图五所示：图五下弦杆该截面特性如下：A=60112mm5118.602mm，xi=28.2mm，yi=78.2mm。4长细比计算：35038.10682.2300iloxxx35072.17082.71335iloyyyaaMP215MP08.18360111100500AN满足要求。3、端斜杆aB：已知杆件轴力N＝-574.70kN，oyoxll＝2390mm。因为oyoxll，故采用不等肢角钢，长肢相并，使xi≈yi，选用角钢2∟1258010，如图六所示：图六端斜杆则其截面特性如下：A＝39422mm，xi＝39.8mm，yi＝33.9mm对该截面验算如下：05.6039.82390iloxxx，50.709.332390iloyyy又因为：34.1480/239048.0810/80/2tb所以：取15033.791023909009.1150.7009.1122422042tlbyyyz因为：yzx，只需求y，查轴心受压杆稳定系数表得yz=0.692，于是有：68.2103942692.01070.5743ANyN/2mmf215N/2mm所需截面合适。4、腹杆eg-gK：此杆在g节点处不断开，采用通长杆件。最大拉力：kNN84.140gK，kNNeg52.100；最大压力：kNN41.34gK，kNNeg96.37；再分式桁架中的斜腹杆，在桁架平面内的计算长度取节间中心间距：oxl=2027mm在桁架平面外的计算长度：mmNNlloy3960)96.3741.3425.075.0(4055)25.075.0(121选用2∟10010，如图七所示。5图七腹杆eg-gK查角钢规格表得:A=38522mm，xi=30.5mm，yi=46.0mm。对此截面验算如下：15046.665.302027xxoxil，15009.860.463960ioylyy又因为：97.22100/396058.0/58.01010/100/bltboy所以取：15070.88103960100475.0109.86475.01224224tlboyyyz因为：yzx只需求yz，查表得yz=0.630，于是有：压应力：aaMP215MP1563852630.0379600ANy，满足要求。拉应力：MPaMPaAN21556.363852140840，满足要求。5.竖杆Ie：该杆件N＝-82.85KN，llx8.00＝0.82801＝2241mm，mmlloy2801由于杆件内力较小，按=[]=150选择，需要的回转半径为：mmlioxx9.141502241][，mmlioyy67.181502801][，查型钢表，选用2L63×8,如图八所示：图八中竖杆其截面特性为：A=19022mm，xi=19.0mm，yi=31.0mm对此截面验算如下：1502.15119.42241iloxxx，15092.14.302801iloyyy6因为：b/t=63/8=7.8750.58oyl/b=0.582801/63=25.787所以：15047.938280163475.011.92475.01224224tlboyyyz因为xyz，只需求x，查表得x=0.463，于是有：aaMP215MP1.949021634.082850ANx其余各杆件截面选择过程不一一列出，计算结果见表二：架杆件截面选择表表二名称杆件编号内力（KN）计算长度（cm)截面规格截面面积（cm2）容许长细比[]计算应力2N/mmxl0yl0上弦IJJK-1139.63135.50406.502L180×110×1267.42150.00206.45下弦de1100.50270.001335.002L160×100×1260.10350.00183.08腹杆Aa-27.62191.50191.502L63×819.02150.0094.10aB-574.70239.00239.002L125×80×1039.42150.00210.68Bb455.48239.00298.752L100×1038.52350.00118.25Cb-55.23212.70265.882L63×819.02150.0059.637、节点设计用E43焊条时，角焊缝的抗拉、抗压和抗剪强度设计值160wff2N/mm。1、下弦节点“