【单选题】框架梁KL2的截面尺寸为300mm×800mm,跨中截面底部纵向钢筋为4 25。已知该截面处由永久荷载和可变荷载产生的弯矩标准值MDK、MLK,分别为250kN.m、100kN.m。试问,该梁跨中截面考虑荷载长期作用影响的最大裂缝宽度w2max(mm)与下列何项数值最为接近? 提示:cs=30mm,h0=755mm。
【简答题】A.Moveable metal type began to be used in printing. B.Chinese printing technology was first introduced. C.The earliest known book was published. D.Metal type was imported from Korea.
【多选题】在线电压UL =220V,频率 f =50Hz的三相电源上,接一个对称三角形联结的感性负载,已知每相阻抗Zp =8 Ω,则以下参数正确的是()
【简答题】function y=two_min(x) if x<20 y=-exp(-(x/20).^2); else y=-exp(-1)+(x-20)*(x-22); end
【简答题】计算题:已知梁的截面尺寸为b×h=250mm×450mm,安全级别为II级(安全系数1.2);受拉钢筋为4根直径为16mm的HRB335钢筋(抗拉强度设计值300N/mm 2 ),A s =804mm 2 ;混凝土强度等级为C40(抗压强度设计值19.1N/mm 2 );承受的弯矩设计值M=59kN•m。环境类别为一类(c=30mm)。按SL-2008规范验算此梁截面是否安全。
【单选题】The young inventor wants to take out a ________ on his new type of printing machine.
【简答题】已知某混凝土单筋矩形截面梁截面尺寸为b×h=250mm×450mm,安全等级为二级,环境类别为一类,混凝土强度等级为C30,配置HRB335级纵向受拉钢筋4 20( =1256mm 2 ), =35mm。求该梁所能承受的极限弯矩设计值 ?
【单选题】Which type of printing is more convenient based on the passage()
【简答题】invented the art of printing(movable type printing) in the Northern Song Dynasty.
【简答题】三相对称感性负载三角形( D )联结,三相对称电源的线电压为 220V ,测得电路的线电流为 38A ,负载的有功功率为 11.583kW 。试求: 1 电路的功率因数; 2 确定负载的电阻值; 3 确定负载的电抗值。