钢结构屋架计算书21m跨

1目录1设计资料·······················································21．1结构形式······················································21．2屋架形式及选材················································22支撑布置······················································22．1桁架形式及几何尺寸············································22．2桁架支撑布置如图··············································33荷载计算······················································44内力计算······················································55杆件设计·······················································65．1上弦杆························································75．2下弦杆·························································85．3端斜杆aB······················································85．4腹杆···························································95．5竖杆···························································96节点设计·······················································126．1下线节点······················································126．2上线节点······················································136．3屋脊节点······················································146．4支座节点······················································156．5下线中央节点··················································167参考文献·······················································1921、设计资料1．1结构形式某厂房的跨度为21m，长度60m，柱距6m。车间设有两台30/5吨中级工作制吊车。梯形屋架，屋架端高为1.7m，屋面坡度为1/9，屋架支撑在钢筋混凝土柱上，柱的截面为400×400mm，混凝土标号为C25；计算温度最低-20℃，采用1.5×6m预应力钢筋混凝土大型屋面板和卷材屋面。屋面做法：三毡四油绿豆防水层，20mm厚1:3水泥砂浆找平层，80mm厚泡沫混凝土保温层。屋面活荷载标准值0.5KN/M2，雪荷载标准值0.5KN/M2，积灰荷载标准值0.5KN/M2。由于屋面坡度小、重型屋面，不考虑风荷载。1．2屋架形式及选材屋架跨度为21m，屋架形式、几何尺寸如图附图所示。2支撑布置2．1桁架形式及几何尺寸布置171728672850300030001500135815091509150915091509150923042395263329443235236629442633203326991350图1梯形钢屋架形式和几何尺寸32．2桁架支撑布置根据厂房长度、跨度及荷载情况，设置两道上、下弦横向水平支撑。因柱网采用封闭结合，厂房两端的横向水平支撑设在第一柱间。在所有柱间的上弦平面设置了刚性和柔性系杆，以保证安装时上弦杆的稳定，在各柱间下弦平面的跨中及端部设置了柔性系杆，以传递山墙风荷载。在设置横向水平支撑的柱间，于屋架跨中和两端各设一道垂直支撑。梯形钢屋架支撑布置如图1．2所示。桁架上弦支撑布置图桁架下弦支撑布置图垂直支撑垂直支撑43荷载计算屋面荷载和雪荷载不会同时出现，计算时，取较大的荷载标准值进行计算。故取屋面活荷载0.5KN/m2进行计算。屋架沿水平投影面积分布的自重（包括支撑）按经验公式gk=(0.12+0.011l)KN/m2计算，跨度单位为米（m）。荷载计算表荷载名称标准值（kN/m2）设计值（kN/m2）预应力混凝土大型屋面板1.41.4*1.35=1.89三毡四油防水层0.40.4*1.35=0.5420mm厚找平层0.02*20=0.40.4*1.35=0.5480mm厚泡沫混凝土保温层0.08*6=0.480.48*1.35=0.648屋架和支撑自重0.12+0.011*21=0.350.35*1.35=0.473管道荷载0.10.1*1.35=0.135永久荷载总和3.134.226屋面活荷载0.50.5*1.4=0.7积灰荷载0.50.5*1.4=0.7可变荷载总和1.01.4设计屋架时，应考虑以下三种荷载组合。1、全垮永久荷载+全垮可变荷载全垮节点永久荷载及可变荷载：F=（4.226+1.4）×1.5×6=50.634KN２、全垮永久荷载+半跨可变荷载全垮节点永久荷载：F1=4.226×1.5×6=38.034KN半跨可变荷载：F2=1.4×1.5×6=12.6KN3、全垮屋架（包括支撑）自重+半跨屋面板自重+半跨屋面活荷载全垮节点屋架自重：F3=0.473×1.5×6=4.26KN半跨节点屋面板自重及活荷载：F4=（1.89+0.7）×1.5×6=23.31KN51、2为使用节点荷载情况，3为施工阶段荷载情况。4内力计算屋架在上述三种荷载组合作用下的计算简图如下所示。285030003000150015003000300028502070017172867abcdeABCDEFGHF1/2FFFFFFFFFFFFFF/2F1F1F1F1F1F1F1F1F1F1F1F1F1F1/2F2/2F2F2F2F2F2F2F2/2F3/2F3F3F3F3F3F3F3F3F3F3F3F3F3F3/2F4/2F4F4F4F4F4F4F4/2(a)(b)(c)F/2屋架计算简图由图解法或数解法解得F=1的屋架各杆件的内力系数（F=1作用于全垮、左半跨和右半跨）。然后求出各种荷载情况下的内力进行组合，计算结果如下表所示。6屋架杆件内力组合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杆件计算内力（kN）全跨左半跨右半跨F1×①+F2×②F1×①+F2×③F3×①+F4×②F3×①+F4×③①②③上弦杆AB000000000BC、CD-8.421-5.984-2.789-426.389-395.683-355.426-175.361-100.885-426.389DE、EF-12.343-8.043-4.921-624.975-570.795-531.458-240.064-167.29-624.975FG、GH-13.057-7.355-6.527-661.128-589.283-578.85-227.068-207.767-661.128下弦杆ab4.683.4361.424236.9671221.293195.9415100.0353.130236.967bc10.8097.3913.912547.3029504.2361460.4007218.3306137.235547.303cd12.9427.9265.741655.3052592.1036564.5726239.888188.956655.064de12.4836.2417.144632.0642553.415564.793198.655219.7042632.0642斜腹杆aB-8.01-5.88-2.438-405.578-378.74-335.371-171.185-90.9524-405.578Bb5.9144.0272.159299.450275.6733252.1365119.06375.51993299.450bD-4.322-2.811-2.022-218.84-199.802-189.86-83.9361-65.5445-218.84Dc2.5881.071.737131.0408111.914120.31835.9665851.51435131.041cF-1.3230.134-1.668-66.989-48.6306-71.336-2.51244-44.5171-66.989Fd0.069-1.2081.4623.493746-12.596521.0456-27.86534.37334.373dH1.0662.305-1.41853.97669.58722.6774458.271-28.512469.587竖杆Aa-0.5-0.50-25.317-25.317-19.017-13.785-2.13-25.317Cb、Ec-1-10-50.634-50.634-38.034-27.57-4.26-50.634Gd-1-10-50.634-50.634-38.034-27.57-4.26-50.634He00000000075杆件设计5．1上弦杆整个上弦采用等截面，按FG、GH杆件的最大设计内力设计，即N=-661.128KN上弦杆计算长度：在屋架平面内为节间轴线长度，即l0x=l0=1.509m在屋架平面外，本屋架为无檩体系，并且认为大型屋面板只起到刚性系杆作用，根据支撑布置和内里变化情况，取l0y为节点间的距离，即l0y=3m。根据屋架平面外上弦杆的计算长度，上弦截面选用两个不等肢角钢，短肢相并，如右图所示。上弦截面腹杆最大内力N=-405.578KN，查表可知，中间节点板厚度选用10mm，支座节点板厚度选用12mm。设λ=60，查Q235钢的稳定系数表，可得807.0（由双角钢组成的T形和十字形截面均属于b类），则需要的截面积为mmfNA4.3810215807.01000128.661需要的回转半径：mmimmliyxx0.50603,15.2560509.10根据需要A、xi、yi查角钢规格表，选用2L140×90×12，肢背间距a=10mm，则A=52.80cm2，cmicmiyx81.6,54.2按所选角钢进行验算：805.441.68300041.594.25150900yyyxxxilil满足长细比≤[150]的要求。由于xy，只需要y。查表813.0y，则MPaMPaANx21501.1545280813.01000128.661，故所选截面合适。5．2下弦杆整个下弦杆采用同一截面，按最大内力所在的杆计算N=655.064KNmmlmmlyox10350220700,30000所需截面积为28.30462151000064.655mmfNA选用2L125×80×12，因oxoyll，下弦截面故用不等肢角钢，短肢相并，如右图所示。3500.1686.6110350,3509.1334.22300016.6,24.2,468.3070.4622yoyyxoxxyxililcmicmicmcmA5．3端斜杆aB杆件轴力：NKNN405578578.405计算长度：mmlloyox2304因为