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【电大】钢结构（本）汇总整编一、单项选择题1下列关于我国目前的钢结构设计说法正确的一项是（ C ）C.除疲劳计算按容许应力幅、应力按弹性状态计算外，其他采用以概率理论为基础的近似概率极限状态设计方法2按承载力极限状态设计钢结构时，应考虑（ C ）C荷载效应的基本组合，必要时尚应考虑荷载效应的偶然组合3在结构设计中，失效概率与可靠指标的关系为（ B ）B 越大，越小，结构可靠性越差4下列钢结构计算所取荷载设计值和标准值，符合钢结构设计规范的一组是 （ B ）B计算结构或构件的强度、稳定性以及连接的强度时，应采用荷载设计值；5塔架和桅杆的结构形式属于（ A ） A高耸钢结构 6相同跨度的结构承受相同的荷载，普通钢屋架的重量为钢筋混凝土屋架的（B1/41/3）7在构件发生断裂破坏前，具有明显先兆的情况是（ B ） B 塑性破坏 8钢材的设计强度是根据（ C ）确定的 C屈服点 9钢材的三项主要力学性能为（ A ） A抗拉强度、屈服点、伸长率 10钢材的伸长率是反映材料（ D ）的性能指标。 D 塑性变形能力11钢结构对动力荷载适应性较强，是由于钢材具有（C ） C良好的韧性 12四种厚度不等的16Mn钢钢板，其中（ A ）钢板设计强度最高 A16mm 13钢中硫和氧的含量超过限量时，会使钢材（ B ） B热脆 14以下关于应力集中的说法中正确的是（ B ） B应力集中产生同号应力场，使塑性变形受到限制15钢材在低温下，冲击韧性（ B ） B降低16钢材经历了应变硬化（应变强化）之后（ A ） A强度提高 17下列因素与钢构件发生脆性破坏无直接关系的是（ A ） A钢材屈服点的大小 18钢材的疲劳破坏属于（ C ） C脆性破坏 19对钢材的疲劳强度影响不显著的是（ C ） C钢种 20沸腾钢与镇静钢冶炼浇注方法的主要不同之处是（ C ） C沸腾钢不加脱氧剂 1、焊接残余应力不影响构件的（ B ） B静力强度 2、在弹性阶段，侧面角焊缝应力沿长度方向的分布为（ C ）C两端大、中间小 3、焊缝长度方向与作用力垂直的角焊缝是（ A ）A正面角焊缝 4、关于重级工作制吊车焊接吊车梁的腹板与上翼缘间的焊缝说法正确的是（ D ）D可采用二级焊透对接焊缝5、在钢梁底面设有吊杆，其拉力设计值为650kN（静载），吊杆通过节点板将荷载传给钢梁，节点板采用双面焊缝焊于梁下翼缘，=10mm，=160MPa，则每面焊缝长度为（260mm）6、部分焊透的对接焊缝的计算应按（ B ）。B角焊缝 7、斜角焊缝主要用于（ C ）。C 钢管结构 8、按照施焊位置分为平焊、横焊、立焊及仰焊，其中操作条件最差的是（ D ）仰焊9、一个承受剪力作用的普通螺栓在抗剪连接中的承载力是（ D ）D A、B中的较小值10、C级普通螺栓连接可用于（ B ）B屋盖支撑的连接 11、下列关于螺栓在构件排列的相关要求说法有误的一项是（ A ）A垂直于受力方向的受拉构件，各排螺栓的中距越小越好 12、承受轴心力作用的高强度螺栓摩擦型受剪切连接中，其净截面强度验算公式，下列与轴心拉杆所受的力相比关系正确的是（ B ）。B 13、高强度螺栓摩擦型连接和承压型连接主要区别是（D）。D. 设计计算方法不同14、摩擦型连接的高强度螺栓在杆轴方向受拉时，其承载力说法正确的一项是（ C ）C与螺栓直径有关 15、高强度螺栓摩擦型连接受剪破坏时，承载能力极限状态的确定因素是（ B ）。B连接板件间的摩擦力 16、13在钢梁底面设置吊杆，其拉力设计值为650kN，吊杆通过T形连接件将荷载传给钢梁，T形连接件与钢梁下翼缘板采用双排88级M20高强度螺栓摩擦型连接，预拉力P=125kN，抗划系数U=045，则高强度螺栓的数量应为（ C ）。C8 17、采用高强度螺栓摩擦型连接与承压型连接，在相同螺栓直径的条件下，它们对螺栓孔的要求是（ A ）A摩擦型连接孔要求略大，承压型连接孔要求略小18、承压型高强度螺栓可用于（D）。D 承受静力荷载或间接承受动力荷载结构的连接19、每个受剪力作用的摩擦型高强度螺栓所受的拉力应低于其预拉力的（C）。C 08倍 20、图1所示为高强度螺栓连接，在弯矩M的作用下，可以认为中和轴在（C螺栓 3上） 1、实腹式轴心受拉构件计算的内容包括（D）。D强度、刚度（长细比）2、对有孔眼等削弱的轴心拉杆承载力，钢结构设计规范采用的准则为净截面（ B ）B平均应力达到钢材屈服点 3、一宽度为、厚度为的钢板上有一直径为的孔，则钢板的净截面面积为（ C ）C 4、下列关于轴心压杆的强度与稳定的计算公式（为构件的净截面，为构件的毛截面）正确的一项是（ B ） 轴心压杆的强度与稳定，应分别满足（ B ）。B 5、计算格构式轴心受压柱整体稳定时，用换算长细比代替，这是考虑（ D ）D缀材剪切变形的影响6、双肢缀条式轴心受压柱绕实轴和绕虚轴等稳定的要求是（B ）B 7、确定轴心受压实腹柱的截面形式时，应使两个主轴方向的长细比尽可能接近，其目的是（ C ） C达到经济效果 8、提高轴心受压构件局部稳定常用的合理方法是（D ） D设置横向加劲肋9、为提高轴心受压构件的整体稳定，在构件截面面积不变的情况下，构件截面的形式应使其面积分布（ B ）。 B 尽可能远离形心 10、轴心受压构件发生弹性失稳时，截面上的平均应力（ C ）。 C 低于钢材比例极限11、轴心受压构件柱脚底板的面积主要取决于（ C ）C基础材料的抗压能力12、两端铰接的理想轴心受压构件，当截面形式为双轴对称十字形时，在轴心压力作用下构件可能发生（C）。C扭转屈曲 13、在下列关于柱脚底板厚度的说法中，错误的是（ C ）C 其它条件相同时，四边支承板应比三边支承板更厚些14、下列轴心受拉构件，可不验算正常使用极限状态的是 （D）D 预应力拉杆15、双肢格构式受压柱，实轴为xx，虚轴为yy，应根据（ B ）确定肢件间距离。B 16、承受横向荷载的构件称为（ A ）A 受弯构件 17、钢梁弯曲应力的发展三个阶段分别是（ A ）A弹性工作阶段、弹塑性工作阶段、塑性工作阶段18、提高腹板的稳定性，相对比较经济的措施是（ A ）A增大腹板面积19、梁的挠度验算其实是（ C ）C验算梁的刚度20、计算工字形截面梁的抗弯强度采用公式，取=105，梁的受压翼缘外伸肢宽厚比不大于（ B ）A B 1、验算工字形截面梁的折算应力的公式，式中、应为（ D ）D验算截面中验算点的正应力和剪应力2、不考虑腹板屈曲后强度，工字形截面梁腹板高厚比=100时，梁腹板可能（ D ）D因剪应力引起屈曲，需设横向加劲肋3、梁上作用较大固定集中荷载时，其作用点处应（ B ）。B 设置支承加劲肋4、焊接工字形截面梁腹板设置加劲肋的目的是（ D ）。D 提高梁的局部稳定性5、保证工字形截面梁受压翼缘局部稳定的方法是（ D ）D限制其宽厚比6、对于承受均布荷载的热轧H型钢简支梁，应计算（ D ）D抗弯强度、抗剪强度、整体稳定、挠度7、一简支箱形截面梁，跨度60m，梁宽1m，梁高36m，钢材为16Mn，在垂直荷栽作用下，梁的整体稳定系数为（ D ）D1008、在焊接组合梁的设计中，腹板厚度应（ C ）。C 厚薄相当D 厚薄无所谓9、在焊接工字形组合梁中，翼缘与腹板连接的角焊缝计算长度不受的限制，是因为（ D ）。D 内力沿侧面角焊缝全长分布的关系10、工字形截面梁受压翼缘，对Q235钢，保证局部稳定的宽厚比限值为，对Q345钢，此宽厚比限值应为（ A ）A比15更小 11、为了提高梁的整体稳定，最经济有效的办法是（B）B 增加侧向支撑点 12、当无集中荷载作用时，焊接工字形截面梁翼缘与腹板的焊缝主要承受（ C ）。C 水平剪力13、图1所示为加强受压翼缘的工字形等截面简支组合梁，抗侧移支撑杆设置对提高梁的整体稳定性效果最好。（A）图114、单轴对称的实腹式压弯构件整体稳定性计算公式和中的、说法正确的是（ D ）D和为单轴对称截面绕非对称轴较大和较小翼缘最外纤维的毛截面模量，值相同15、有侧移的单层钢框架，采用等截面柱，柱与基础固接，与横梁铰接，框架平面内柱的计算长度系数为（ A ）A203 16、单轴对称截面的压弯构件，当弯矩作用在对称轴平面内，且使较大翼缘受压时，构件达到临界状态的应力分布说法正确的是（ A ）A 可能在拉、压侧都出现塑性 17、实腹式偏心受压构件在弯矩作用平面内整体稳定验算公式中的主要是考虑 （ A ）。A 截面塑性发展对承载力的影响 18、单轴对称截面的压弯构件，一般宜使弯矩（ A ）A绕非对称轴作用 19、计算格构式压弯构件的缀材时，剪力应取（ C ）。C 构件实际剪力设计值或由公式计算的剪力两者中较大值20、关于屋架的形式说法有误的一项是（ B ）B 屋架外形选择最重要的方面是用料经济，其次是建筑物用途 二、判断题1钢结构在涂刷油漆前应彻底除锈，油漆质量和涂层厚度均应符合相关规范要求。（）2正常使用极限状态包括构件和连接的强度破坏、疲劳破坏和因过度变形而不适于继续承载，结构和构件丧失稳定，结构转变为机动体系和结构倾覆。（）3轻钢结构主要包括钢-混凝土组合梁和钢管混凝土柱等。（）4钢结构计算的目的在于保证所设计的结构和构件满足预期的各种功能。（）5用作钢结构的钢材必须具有较高的强度、足够的变形能力和良好的工艺性能。（）6钢材在单向受压（粗而短的试件）时，受力性能基本和单向受拉时相同。（）7钢筋的冷弯试验是按照有关规定的弯心直径在试验机上采用冲头加压，使试件完成45，如试件外表面不出现裂纹和分层，即为合格。（）8碳含量在0.120.20范围内碳素钢，可焊性好。（）9实践证明，构件的压力水平越低，越容易发生疲劳破坏。（）10槽钢分为普通槽钢和轻型槽钢，其编号的依据是其截面宽度（单位m）。（）1、钢结构的连接就是把板材或型钢组合成构件，再将构件组合成结构，以保证结构的共同受力。( )2、侧面角焊缝主要承受剪力、塑性较差、但弹性模量较高，强度也高。（ ）3、采用角焊缝连接的板件必须坡口，焊缝金属不可直接充填在由被连接板件形成的直角或斜角区域内。（ ）4、焊缝的连接形式按被连接板件的相互位置可分为对接、搭接、T型连接和角部连接四种形式。( )5、在荷载作用下，如果焊缝长度适宜，当焊缝两端点处的应力达到屈服强度后，继续加载，应力会逐渐均匀。( )6、焊接冷却后产生的变形称为焊接残余变形，这时焊件中的应力称为焊接残余应力。( )7、9螺栓错列排列比较简单整齐，布置紧凑，所用连接板尺寸小，但对构件截面的削弱较大。（ ）8、普通螺栓连接的抗剪承载力，应考虑螺栓杆受剪和孔壁承压两种情况。( )9、高强度螺栓连接时的摩擦力随外力增大而增大，接近破坏时，与杆身共同承担剪力。（ ）10、高强度螺栓群在扭矩或扭矩、剪力共同作用时的剪力计算方法与普通螺栓群完全不同，其应采用高强度螺栓承载力的极限值进行计算。( ) 1、轴心受力构件包括轴心受拉构件和轴心受压构件。( ) 2、轴心受力构件的强度制其长细比来保证。( ) 3、单轴对称截面构件绕对称轴屈曲时，在发生弯曲变形的同时绝对不发生扭转。（）4、残余应力对轴心受压构件承载力的影响，主要考虑纵向残余应力。( )5、具有初始弯曲的压杆，压力一开始作用，杆件就产生挠曲，并随着荷载的增大而增加。( )6、组成轴心受压构件的板件过薄，在压力作用下容易发生局部失稳。( )7、实腹式轴心受压构件一般采用单轴对称截面来避免弯曲失稳。( )8、格构式构件轴心受压构件挠实轴的稳定性计算与实腹式轴心受压构件相同。( )9、轴心受压柱的柱头构造应使柱身的内力可靠地传给基础，并和基础牢固地连接。( )10、组合梁相比型钢梁加工简单，成本较低，因而应优先选用组合梁。( )1、梁主要用于承受弯矩，为了充分发挥材料的强度，其截面通常设计成高而窄的形式。（）2、横向荷载的临界值仅与它自身大小有关，而与沿梁高的作用位置无关。（）3、对于承受静力荷载和间接承受动力荷载的组合梁，坚决不允许腹板在梁整体失调之前屈曲。（）4、型钢梁腹板和翼缘的宽厚比都比较小，局部稳定常可得以保证，不需要进行验算（）5、钢结构中主梁和次梁的连接形式一般有叠接和平接两种。（）6、同时承受轴向拉力或弯矩的构件称为拉弯构件，同时承受轴向压力或弯矩的构件称为压弯构件。（）7、压弯构件的受压翼缘板，其应力情况与梁受拉翼缘基本相同，因此其受压翼缘宽厚比限梁受拉翼缘的宽厚比限制相同。（）8、梁与柱的刚性连接要求连接节点不仅能可靠地传递剪力而且能有效地传递弯矩。（）9、钢材的切割有剪切、锯切和气割等方法，其中剪切机切割最复杂。（）10、焊接钢结构最费工的工序是制孔、装配和打铆。（）三、简答题1、钢结构和其他材料的结构相比具有哪些特点？答：（1）建筑钢材强度高，塑性和韧性好；（2）钢结构的重量轻；（3）材质均匀，与力学计算的假定比较符合；（4）钢结构制作简便，施工工期短；（5）钢结构密闭性好；（6）钢结构耐腐蚀性差；（7）钢材耐热不耐火；（8）钢结构可能发生脆性断裂。2.钢材“耐热不耐火”的含义是什么？规范对其有何规定？答：钢材受热，当温度在200以内时，其主要力学性能，如屈服点和弹性模量降低不多。温度超过200后，材质发生较大变化，不仅强度逐步降低，还会发生蓝脆和徐变现象。温度达600时，钢材进入塑性状态不能继续承载。因此，钢结构设计规范规定钢材表面温度超过150后即需加以隔热防护，对需防火的结构，应按相关的规范采取防火保护措施。3、钢结构设计必须满足的功能包括哪些方面？答：（1）应能承受在正常施工和正常使用时可能出现的各种情况，包括荷载和温度变化、基础不均匀沉降以及地震作用等；（2）在正常使用情况下结构具有良好的工作性能；（3）在正常维护下结构具有足够的耐久性；（4）在偶然事件发生时及发生后仍能保持必需的整体稳定性。4、时效硬化和人工时效各指什么？答：时效硬化：在高温时熔化于铁中的少量碳和氮，随着时间的增长逐渐从纯铁中析出，形成自由碳化合物和氮化物，对纯铁体的塑性变形起遏制作用，从而使钢材的强度提高，塑性、韧性下降，这种现象称为时效硬化，俗称老化。人工时效：时效硬化的过程一般很长，在材料塑性变形后加热，可以使时效硬化发展特别迅速，这种方法称为人工时效。5、什么情况下会产生应力集中，应力集中对钢材性能有何影响？答：在钢结构的构件中可能存在孔洞、槽口、凹角、截面突然改变以及钢材内部缺陷等，使构件中的应力分布将不再保持均匀，而是在某些区域产生局部高峰应力，在另外一些区域则应力降低，形成所谓应力集中现象。应力集中会使钢材变脆的趋势。6、简述钢材的疲劳破坏过程答：钢材在反复荷载作用下，结构的抗力及性能都会发生重要变化，甚至发生疲劳破坏。根据试验，在直接的连续反复的动力荷载作用下，钢材的强度将降低，即低于一次静力荷载作用下的拉伸试验的极限强度，这种现象称为钢材的疲劳。疲劳破坏表现为突发的脆性断裂。7、钢材常见的冶金缺陷有哪些，各自的具体含义是什么？答：钢材常见的冶金缺陷包括偏析、非金属夹杂、气孔、裂纹及分层等。偏析：是指钢材中化学成分不一到和不均匀，特别是硫、磷偏析严重造成钢材的性能恶化；非金属夹杂：是指钢中含有硫化物与氧化物等杂质；气孔：是浇铸钢锭时，由氧化铁与碳作用所生成的一氧化碳气体不能充分逸出而形成的。8简述温度对钢材性能产生的影响。 答：钢材性能随温度改变而有所变化，总的趋势是温度升高，钢材强度降低，应变增大；反之温度降低，钢材强度会略有增加，同时钢材会因塑性和韧性降低而变脆。1、钢结构焊接连接方法的优点和缺点有哪些？答：优点（1）焊件间可以直接相连，构造简单，制作加工方便；（2）不削弱截面，节省材料；（3）连接的密闭性好，结构的刚度大；（4）可实现自动化操作，提高焊接结构的质量。缺点（1）焊缝附近的热影响区内，钢材的金相组织发生改变，导致局部材质变脆；（2）焊接残余应力和残余变形使受压构件承载力降低；（3）焊接结构对裂纹很敏感，局部裂纹一旦发生，容易扩展至整个截面，低温冷脆问题也较为突出。2、高强度螺栓的预拉力设计值P的计算公式中，系数的确定考虑了哪些因素？答：（1）拧紧螺栓时螺栓同时受到由预拉力引起的拉应力和由扭矩引起的扭转剪应力作用；（2）施工时为了弥补高强度螺栓预拉应力的松弛损失，一般超张拉5%10%，为此考虑一个超张拉系数0.9；（3）考虑螺栓材质的不均匀性，引入一个折减系数0.9；（4）由于以螺栓的抗拉引吭高歌为准，为了安全引入一个安全系数0.9。3、抗剪普通螺栓有哪几种可能的破坏形式？如何防止？答：破坏形式：（1）当螺栓杆直径较小而板件较厚时，螺栓杆可能被剪断；（2）当螺栓杆直径较大、板件较薄时，板件可能被挤坏，由于螺栓杆和板件的挤压是相对的，故也把这种破坏叫做螺栓承压破坏；（3）板件截面可能因螺栓孔削弱太多而被拉断；（4）端距太小，端距范围内的板件可能被螺栓杆冲剪破坏。防止：第（3）种破坏形式属于构件的强度计算，第（4）种破坏形式通过限制螺栓端距大于或等于2d0加以避免。因此，抗剪螺栓连接计算只考虑第（1）、（2）种破坏形式。4、减少焊接应力和焊接变形的设计措施有哪些？答：（1）尽可能使焊缝对称于构件截面的中性轴，以减少焊接变形；（2）采用适宜的焊脚尺寸和焊缝长度；（3）焊缝不宜过分集中（4）尽量避免两条或三条焊缝垂直交叉（5）尽量避免在母材厚度方向的收缩应力。1、实腹式轴心受压构件进行截面选择时，应主要考虑的原则是什么？答；（1）面积的分布应尽量开展，以增加截面的惯性矩和回转半径，提高柱的整体稳定承载力和刚度；（2）两个主轴方向尽量等稳定，以达到经济的效果；（3）便于与其他构件进行连接，尽量能构造简单，制造省工，取材方便。2、计算格构式轴心受压构件绕轴的整体稳定时，为什么采用换算长细比？答：对于格构式轴心受压构件，当绕虚轴失稳时，因肢件之间并不是连续的板而只是每隔一定距离用缀条或缀板联系起来，构件的剪切变形较大，剪力造成的附加影响不能忽略，通常采用换算长细比来考虑缀材剪切变形对格构式轴心受压构件绕虚轴的稳定承载力的影响。3、简述实腹式轴心受压构件的设计步骤？答：（1）假定构件的长细比，求出需要的截面面积A。（2）计算两个主轴所需要的回转半径(3)由计算的截面面积A和两个主回转半径优先选用型钢。（4）由所需要的A、h、b等，以及同时考虑构造要求、局部稳定以及钢材规格等，确定截面的初选尺寸。（5）构件强度、稳定和刚度验算4、钢梁腹板计算高度如何取值？答：（1）轧制型钢梁，为腹板在与上下翼缘相交接处两内弧起点间的距离；（2）焊接组合梁，为腹板高度；（3）铆接组合梁，为上下翼缘与腹板连接的铆钉（或高强螺栓）线间最近距离。1、什么是梁的整体失稳现象？答：梁主要用于承受弯矩，为了充分发挥材料的强度，其截面通常设计成高而窄的形式。荷载作用在最大刚度平面内。当荷载较小时，仅在弯矩作用平面内弯曲；当荷载增大到某一数值后，梁在弯矩作用平面弯曲同时，将突然发生侧向弯曲和扭转，并丧失继续承载的能力，这种现象称为梁的弯扭屈曲或整体失稳。2、根据弹性稳定理论确定框架柱的计算长度时，都做了哪些假定？答：（1）框架只承受作用于节点的竖向荷载，忽略横梁荷载和水平荷载产生梁端弯矩的影响；（2）所有框架柱同时丧失稳定，即所有框架柱同时达到临界荷载；（3）失稳时横梁两端的转角相等。3、实腹式压弯构件截面选择的具体步骤有哪些？答：（1）计算构件的内力设计值；即弯矩设计值MX、轴心压力设计值N和剪力设计值V；（2）选择截面形式；（3）确定钢材及强度设计值；（4）确定弯矩作用平面内和平面外的计算长度；（5）根据经验或已有资料初选截面尺寸；（6）对初选截面进行强度验算、刚度验算、弯矩作用平面内整体稳定性验算、弯矩作用平面外整体稳定验算和局部稳定性验算，如验算不满足要求，则对初选截面进行调整，重新计算，直至满足要求。4、为什么要在桁架组成的屋盖结构中设置支撑系统，支撑系统具体作用体现在哪些方面？答：屋架在其自身平面内为几何形状不变体系并具有较大的刚度，能承受屋架平面内的各种荷载。但是，平面屋架本身在垂直于屋架平面的侧向（屋架平面外）刚度和稳定性则很差，不能承受水平荷载。因此，为使屋架结构有足够的空间刚度和稳定性，必须在屋架间设置支撑系统。保证结构的空间整体作用；避免压杆侧向失稳，防止拉杆产生过大的振动承担和传递水平荷载保证结构安装时的稳定与方便。四、计算题1.如图所示：已知焊缝承受的斜向静力荷载设计值kN，偏心e为30mm，角焊缝的焊脚尺寸，实际长度，钢材为Q235B，焊条为E43型（=160N/mm2）， 焊缝强度增大系数取122。验算直角角焊缝的强度。图1解：将F分解为垂直于焊缝和平行于焊缝的分力 直角角焊缝的强度满足要求 2.如图所示支柱上下端均为铰接且设置支撑。支柱长度为9m，在两个三分点处均有侧向支撑，以阻止柱在弱轴方向的过早失稳。构件的设计压力为N250kN，容许长细比。支柱截面为工字形I20a，。钢材为Q235（）。验算此支柱的整体稳定和刚度。（截面挠x轴属于a类截面，截面挠y轴属于b类截面）a类截面的整体稳定系数：01234567891100.5630.5550.5480.5410.5340.5270.5200.5140.5070.500b类截面的整体稳定系数：01234567891400.3450.3410.3370.3330.3290.3260.3220.3180.3150.311图1解：先计算长细比， 计算得，取 根据 所以此柱的整体稳定性和刚度均满足要求。3.图2所示简支梁长6m，采用I36a（,），已知单位长度得质量为59.9kg/m，梁的自重为59.99.8587N/m，cm4，cm3，cm，mm。梁上作用恒荷载，荷载密度q=35000N/m，荷载分项系数1.2，截面塑性发展系数，。试验算此梁的正应力及支座处剪应力。（13分）q图2【解】：梁自重产生的弯矩为： Nm （2分） 外荷载在跨中产生的最大弯矩为： Nm （2分） 总弯矩为： Nm （1分） 验算弯曲正应力： N/mm2215 N/mm2 （3分） 验算支座处最大剪应力： 支座处剪力： V1/2 (3500065876 )1.2 128113.2 N （2分） 剪应力： 3N/mm2125 N/mm2 （3分）请您删除一下内容，O(_)O谢谢！2016年中央电大期末复习考试小抄大全，电大期末考试必备小抄，电大考试必过小抄Basketball can make a true claim to being the only major sport that is an American invention. From high school to the professional level, basketball attracts a large following for live games as well as television coverage of events like the National Collegiate Athletic Association (NCAA) annual tournament and the National Basketball Association (NBA) and Womens National Basketball Association (WNBA) playoffs. And it has also made American heroes out of its player and coach legends like Michael Jordan, Larry Bird, Earvin Magic Johnson, Sheryl Swoopes, and other great players. At the heart of the game is the playing space and the equipment. The space is a rectangular, indoor court. The principal pieces of equipment are the two elevated baskets, one at each end (in the long direction) of the court, and the basketball itself. The ball is spherical in shape and is inflated. Basket-balls range in size from 28.5-30 in (72-76 cm) in circumference, and in weight from 18-22 oz (510-624 g). For players below the high school level, a smaller ball is used, but the ball in mens games measures 29.5-30 in (75-76 cm) in circumference, and a womens ball is 28.5-29 in (72-74 cm) in circumference. The covering of the ball is leather, rubber, composition, or synthetic, although leather covers only are dictated by rules for college play, unless the teams agree otherwise. Orange is the regulation color. At all levels of play, the home team provides the ball. Inflation of the ball is based on the height of the balls bounce. Inside the covering or casing, a rubber bladder holds air. The ball must be inflated to a pressure sufficient to make it rebound to a height (measured to the top of the ball) of 49-54 in (1.2-1.4 m) when it is dropped on a solid wooden floor from a starting height of 6 ft (1.80 m) measured from the bottom of the ball. The factory must test the balls, and the air pressure that makes the ball legal in keeping with the bounce test is stamped on the ball. During the intensity of high school and college tourneys and the professional playoffs, this inflated sphere commands considerable attention. Basketball is one of few sports with a known date of birth. On December 1, 1891, in Springfield, Massachusetts, James Naismith hung two half-bushel peach baskets at the opposite ends of a gymnasium and out-lined 13 rules based on five principles to his students at the International Training School of the Young Mens Christian Association (YMCA), which later became Springfield College. Naismith (1861-1939) was a physical education teacher who was seeking a team sport with limited physical contact but a lot of running, jumping, shooting, and the hand-eye coordination required in handling a ball. The peach baskets he hung as goals gave the sport the name of basketball. His students were excited about the game, and Christmas vacation gave them the chance to tell their friends and people at their local YMCAs about the game. The association leaders wrote to Naismith asking for copies of the rules, and they were published in the Triangle, the school newspaper, on January 15,1892. Naismiths five basic principles center on the ball, which was described as large, light, and handled with the hands. Players could not move the ball by running alone, and none of the players was restricted against handling the ball. The playing area was also open to all players, but there was to be no physical contact between players; the ball was the objective. To score, the ball had to be shot through a horizontal, elevated goal. The team with the most points at the end of an allotted time period wins. Early in the history of basketball, the local YMCAs provided the gymnasiums, and membership in the organization grew rapidly. The size of the local gym dictated the number of players; smaller gyms used five players on a side, and the larger gyms allowed seven to nine. The team size became generally established as five in 1895, and, in 1897, this was made formal in the rules. The YMCA lost interest in supporting the game because 10-20 basketball players monopolized a gymnasium previously used by many more in a variety of activities. YMCA membership dropped, and basketball enthusiasts played in local halls. This led to the building of basketball gymnasiums at schools and colleges and also to the formation of professional leagues. Although basketball was born in the United States, five of Naismiths original players were Canadians, and the game spread to Canada immediately. It was played in France by 1893; England in 1894; Australia, China, and India between 1895 and 1900; and Japan in 1900. From 1891 through 1893, a soccer ball was used to play basketball. The first basketball was manufactured in 1894. It was 32 in (81 cm) in circumference, or about 4 in (10 cm) larger than a soccer ball. The dedicated basketball was made of laced leather and weighed less than 20 oz (567 g). The first molded ball that eliminated the need for laces was introduced in 1948; its construction and size of 30 in (76 cm) were ruled official in 1949. The rule-setters came from several groups early in the 1900s. Colleges and universities established their rules committees in 1905, the YMCA and the Amateur Athletic Union (AAU) created a set of rules jointly, state militia groups abided by a shared set of rules, and there were two professional sets of rules. A Joint Rules Committee for colleges, the AAU, and the YMCA was created in 1915, and, under the name the National Basketball Committee (NBC) made rules for amateur play until 1979. In that year, the National Federation of State High School Associations began governing the sport at the high school level, and the NCAA Rules Committee assumed rule-making responsibilities for junior colleges, colleges, and the Armed Forces, with a similar committee holding jurisdiction over womens basketball. Until World War II, basketball became increasingly popular in the United States especially at the high school and college levels. After World War II, its popularity grew around the world. In the 1980s, interest in the game truly exploded because of television exposure. Broadcast of the NCAA Championship Games began in 1963, and, by the 1980s, cable television was carrying regular season college games and even high school championships in some states. Players like Bill Russell, Wilt Chamberlain, and Lew Alcindor (Kareem Abdul-Jabbar) became nationally famous at the college level and carried their fans along in their professional basketball careers. The womens game changed radically in 1971 when separate rules for women were modified to more closely resemble the mens game. Television interest followed the women as well with broadcast of NCAA championship tourneys beginning in the early 1980s and the formation of the WNBA in 1997. Internationally, Italy has probably become the leading basketball nation outside of the United States, with national, corporate, and professional teams. The Olympics boosts basketball internationally and has also spurred the womens game by recognizing it as an Olympic event in 1976. Again, television coverage of the Olympics has been exceptionally important in drawing attention to international teams. The first professional mens basketball league in the United States was the National Basketball League (NBL), which debuted in 1898. Players were paid on a per-game basis, and this league and others were hurt by the poor quality of games and the ever-changing players on a team. After the Great Depression, a new NBL was organized in 1937, and the Basketball Association of America was organized in 1946. The two leagues came to agree that players had to be assigned to teams on a contract basis and that high standards had to govern the game; under these premises, the two joined to form the National Basketball Association (NBA) in 1949. A rival American Basketball Association (ABA) was inaugurated in 1967 and challenged the NBA for college talent and market share for almost ten years. In 1976, this league disbanded, but four of its teams remained as NBA teams. Unification came just in time for major television support. Several womens professional leagues were attempted and failed, including the Womens Professional Basketball League (WBL) and the Womens World Basketball Association, before the WNBA debuted in 1997 with the support of the NBA. James Naismith, originally from Al-monte, Ontario, invented basketball at the International YMCA Training School in Springfield, Massachusetts, in 1891. The game was first played with peach baskets (hence the name) and a soccer ball and was intended to provide indoor exercise for football players. As a result, it was originally a rough sport. Although ten of Naismiths original thirteen rules remain, the game soon changed considerably, and the founder had little to do with its evolution. The first intercollegiate game was played in Minnesota in 1895, with nine players to a side and a final score of nine to three. A year later, the first five-man teams played at the University of Chicago. Baskets were now constructed of twine nets but it was not until 1906 that the bottom of the nets were open. In 1897, the dribble was first used, field goals became two points, foul shots one point, and the first professional game was played. A year later, the first professional league was started, in the East, while in 1900, the first intercollegiate league began. In 1910, in
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