钢结构芬克式屋架课程设计

一、屋架选型初选芬克式屋架基本形状及尺寸参数如下图所示：屋面坡度5.2:1i，坡角08.21arctani，3714.0sin，9285.0cos屋架计算长度ml7.1715.02180；中间高度mh54.3上弦划分为4个区间，每个区间长度mm2383下弦分为3个区间。区间长度分别为mm2566，mm2566，mm3718上弦每节间设置两根檩条，檩条间设有拉条，檩条间距为mm794。屋架支撑布置如下图所示：二、荷载计算1.恒荷载标准值计算将沿屋面斜面分布的恒荷载换算为沿水平投影面分布的荷载，应乘以系数077.1cos1。桁架沿水平投影面积分布的自重按经验公式跨度）（011.012.0wP计算。两层多波压型钢板：2/172.008.02077.1mkN矿渣棉板保温层：2/086.008.0077.1mkN桁架自重：2/318.018011.012.0mkN合计：2/576.0mkN2.活荷载标准值不上人屋面活载2/5.0mkN三、檩条设计1.荷载与内力计算檩条线荷载标准值2/854.0794.05.0794.0576.0mkNqk线荷载设计值：由恒载效应控制2/006.1794.0)5.07.04.1576.035.1(mkNq由活荷载效应控制2/105.1794.0)5.04.1576.02.1(mkNq则2/026.1cosmkNqqy2/410.0sinmkNqqx弯矩设计值：mkNlqMxyx617.4812，mkNlqMyxy461.0812对X轴的净截面模量3645.2021505.110617.4cmfMWxxnx对Y轴的净截面模量3604.221505.110461.0cmfMWxxnx选用槽钢［1043.198cmIx37.39cmWnxcmix94.346.25cmIy38.7cmWnycmiy42.12.截面验算1)因檩条间设有拉条，故可不验算整体稳定2)强度验算223636/215/160108.72.110461.0107.3905.110617.4mmNfmmNWMWMnyyynxxx故强度满足要求3)刚度验算2/854.0mkNqk（验算刚度时应取荷载的标准值）檩条在垂直于屋面方向最大挠度为：mmEIlqxkx8.32103.1981006.2384)106(9285.0854.05384545434允许最大挠度mmmml8.32401506000150故刚度满足设计要求四、屋架设计1.节点集中荷载计算檩条作用在屋架上弦杆的集中荷载kNlF63.626105.122q2中间节点处集中荷载kNFF89.1963.633端节点处集中荷载kNF945.989.1921等效荷载示意图如下示：2.屋架内力计算各杆件内力系数如下图示：各杆件内力设计值檩条集中荷载作用mkNFlM89.4)cos3794.0(63.63131200端节点弯矩mkNMM91.38.001其他节间的正弯矩和节点负弯矩mkNMM93.26.0023.上弦杆截面设计整个上弦杆采用等截面，按最大内力杆ABNNmax设计kNNAB36.187（压杆）杆端mkNM91.31，mkNM93.22选用角钢2L100×7等肢相拼成T形截面26.27cmAncmix09.3cmiy46.43114.96cmWx322.36cmWxcmZ71.20上弦杆是压弯构件1）强度验算223623/215/135102.362.11093.2106.271036.187mmNmmNWMANnxxxn故强度满足要求杆件上弦杆腹杆下弦杆ABBCCDDEBFCFCGCHDHEHGHAFFGGJ系数-9.42-9.05-8.68-8.31-0.931.25-1.861.25-0.933.752.508.757.505.00内力值-187.36-180-172.64-165.29-18.524.86-37.024.86-18.574.5949.73174.04149.1799.452）稳定验算a.由正弯矩控制的平面内长细比：15009.771009.337940xxxil，绕X轴屈曲时属于b类截面，查表可得707.0xkNEANxEx53.85709.771.11006.271006.214.31.125222构件产生反向曲率85.0mx)103.17881036.1878.01(1014.9605.11091.385.0106.27728.01036.187)8.01(3336231ExxxxmxxNNWMAN22/215/90.131mmNmmN满足要求较小翼缘受拉区：)1053.8571036.18725.11(102.362.11091.385.0106.271036.187)25.11(3336232ExxxxmxNNWMAN22/215/37.37mmNmmN满足要求b.由负弯矩控制的平面外由于受压弦杆侧向支撑点间距1l为节间长度l的2倍，且BCABNN则mmNNlly4717)36.18718025.075.0(23794)25.075.0(12108.1056.4447170yyyil3.27100471758.058.03.1471000bltby换算长细比15041.110)74717100475.01(8.105)475.01(2242204tlbyyyz绕y轴屈曲时处于b类截面由41.110yz查表可得490.0y构件产生反向曲率85.0tx翼缘受拉且腹板18235183.14yftb故947.02350005.01yybf362311014.96947.01093.285.01106.27490.01036.187xbxtxyWMAN22/215/32.167mmNmmN满足要求4.下弦杆截面设计整个下弦杆采用等截面，故按最大内力AFNNmax设计kNNAF04.174mmlx25660mmly88500所需杆件截面积22309.88092151004.174cmmmfNA选用角钢2L70×45×5短肢相拼成T形截面查表可得：222.11cmAncmix33.2cmiy57.3对于拉杆35007.11523.26.2560xxxil3500.24857.30.8850yyyil2223/215/1.1551022.111004.174mmNmmNANn均满足要求，故下弦杆所选钢材满足设计要求5.腹杆截面设计1)腹杆EG在节点H处不断开，采用通长杆件kNNNEH59.74maxkNNGH73.49mmllx25660mmmmllly513225662210所需杆件截面积22347.33472151059.74cmmmfNA选用角钢2L45×5相拼组成T形截面查表可得：258.8cmAncmix37.1cmiy26.2对于拉杆3503.18737.16.2560xxxil3501.22726.22.5130yyyil2223/215/871058.81059.74mmNmmNANn均满足要求，故腹杆EG所选钢材满足设计要求2)腹杆CF和CHkNN86.24，mm053256628.08.00llx，mmlly25660所需杆件截面积22316.11162151086.24cmmmfNA查表可得：229.4cmAncmix37.1cmiy881.0对于拉杆3509.14937.120530xxxil35025.29181.825660yyyil2223/215/95.571029.41086.24mmNmmNANn均满足要求，故腹杆EG所选钢材满足设计要求选用单角钢L45×5可满足设计要求3)对于腹杆BF和DHkNN50.18（压杆），786.4mm9538.08.00llx，mmlly9530初选单角钢L45×5229.4cmAn，cmix37.1，cmiy881.0，2004.577.134.7860xxxil2002.108881.03.980yyyil45.114595354.09545tb换算长细比2008.124)85.01(2204tlbyyyz由于yyz，所以只求y，由yz查表可得：412.0y223/215/67.104429412.01050.18mmNmmNANny强度、稳定性均满足要求，故所选钢材满足设计要求。4)对于腹杆CGkNNCG0.37（压杆），1524.8mm19068.08.00llxmmlly19060初选用角钢2L45×5相拼组成T形截面288.5cmAn，cmix37.1，cmiy26.2对于压杆2003.11137.148.1520xxxil2003.8426.26.1900yyyil5.2445190658.09545tb换算长细比2001.86)475.01(2204tlbyyyz由yz查表可得：485.0b223/215/74.129858485.0100.37mmNmmNANnb强度、稳定性均满足要求，故腹杆CG所选钢材满足设计要求。五、节点设计由于采用E43型手工焊，Q235级钢材、角焊缝，查表知2/160mmNfwf1．下弦节点F对于CF杆和BF杆取kNN86.24max杆件厚度mmmmt65，mmt35.35.1故可取mmhf4肢背mmfhNlwfew3916047.01086.247.07.031实际焊缝长度mmhlfw47239，取mm50肢尖mmfhNlwfew1716047.01086.243.03.032实际焊缝长度mmhlfw25217，取mm40850或fhmm故杆件BF、CF与节点板的角焊缝长度为肢背、肢尖均50mm，焊脚尺寸4mm根据所求焊缝长度，并考虑杆件之间应有间隙以及装配等误差，按实际比例绘节点详图如上图示，从而可确定节点板尺寸为mmmmmm10170220。节点板与下弦杆满焊，故焊缝长度mmlw220，取mmhf4焊缝承受内力kNN87.2417.14904.174肢背侧焊缝：223/160/4.15)42220(47.021087.2465.0265.0mmNmmNlhNwef故焊缝强度满足要求。2．下弦节点G（考虑运输和施工方便，下弦杆在节点G处断开）对于CG杆和CH杆，取kNN73.49max杆件厚度mmmmt65，mmt35.35.1故可取mmhf4肢背mmfhNlwfew3916047.021073.497.027.031实际焊缝长度mmhlfw47239，取mm50肢尖mmfhNlwfew1716047.021073.493.023.032实际焊缝长度mmhlfw25217，取mm40850或fhmm故杆件BF、CF与节点板的角焊缝长度为肢背、肢