结构力学习题及答案

aaaaaEI34322113??????????????δ22=EIaaaaEI3322113??????δ12=δ21=EIaaaaEI22113?????a1aa11M图2M图(2)计算ω:D=)3(22)34()()(3333222121212111?????????????mEIamEIamEIamEIammmm=0?)31(2121)34(????????=0(其中EIma3??)?2236735??????=0?λ1=1.5405δ;λ2=0.1262δ3118057.05405.111maEI??????3228149.21262.011maEI??????(3)计算振型:141.2415.015405.1342111112122111??????????????mmYY1414.0414.211262.0342121112122212????????????????mmYY6.结构和质量对称的多自由度体系,其振型是正对称或反对的。(对)7.图示结构a杆内力影响线上的最大纵距为?4/3。(对)da=1P6d8.图示悬臂梁不计杆件本身的质量,已知在B点作用的竖向单位力可使B点下移EIl3/3,则此结构的自振频率等于EIml3/3。(错)BAlEIm9.图?a所?示?结?构?的?弯?矩?分?布?形?状?如?图?b?所?示?。(对)?( )( )ab10.图示结构,各杆i=常数,欲使A结点产生单位顺时针转角?A?1,须在A结点施加的外力偶为数-8i。(错)A???图?示?结?构?用?力?矩?分?配?法?计?算?时?分?配?系?数??BC?为???????。(错)4m2m5mABCDIII12.图?示?连?续?梁?中?给?出?的?力?矩?分?配?系?数?是?错?误?的?。(对)llli i 123i 3/118/118/179/17=2=3=1