解： 该结构为对称结构承受对称荷载情况。采用半刚架法，取半刚架简化体系如习题 8-20 解答图[tex=1.929x1.286]YIFMDUznQEIX3kdYeM7AnQ==[/tex]所示。分析简化体系选取位移法基本体系如习题 [tex=2.286x1.143]QIkEzxeqVSGxoxNJpu0nCg==[/tex] 解答图[tex=1.786x1.286]JWe2swZDIQABcJFWvvhKaw==[/tex]所示。[img=601x551]17a672acc65fcdd.png[/img]根据结点 [tex=2.571x1.286]BEinwh4qX1Yfcj/hKWtiGA==[/tex]处附加刚臂中反力矩等于零的静力平衡条件写出位移法方程[tex=12.0x2.786]IfEG3NsBfGhtbCalasoF/6O76Z46F+Sj6wVQAVp/F3JE+wyMGXYszOKtULP6fdFeOOkAXs4MiPJtEwMMNuaFVwW6402vL6fb045i4574cYh6dUOlOsSLA7+lDR7JUwtqWHl8Qj8MIaoVpOTiINdNa3qVlY1fZviO5QKH16BagIU=[/tex]为了计算位移法方程中的刚度系数和自由项, 分别绘出单位弯矩图和荷载作用下的弯矩图, 如习题解答图 [tex=9.357x1.286]h/ItwxGqe1klDvT57a3NeRFcgNOr/V3fRaBbMv9t8R8=[/tex]所示。[tex=19.786x1.214]uNf7475DFfzJI2aqY+eAZyoaUb5n+qB2AICv3Wu2b4SQLc6uOp0EUIjVsTrEYPglhCXSGxIgjKntKUvOwfyzMg==[/tex][tex=18.429x2.429]8G8emsliyVwOKiTe7zhjXZjpxiLgZ2QgshQdDc8UIODRiKiFlf0+7BlioHyRn9mrJVhv9sCajJlmbdcz/c7PpTUKHLQeerfhdlkV9BgvT1Y=[/tex]将求得的刚度系数和自由项代入位移法方程[tex=11.5x5.214]IfEG3NsBfGhtbCalasoF/7r18kPLtQG3JOJHa4bPtBkCMNMznIxAdkKrgihgt2fXLijezJzgWUaoBX3joYFKgBfGKr9k5ZKivIu7qTChuiqqRay9FhgjuJoniRv29vxQZz2+Y/k6AhQspcC+HWPWustNPwnKFGeCwXoXd2OUm4k=[/tex]解方程，得[tex=7.071x5.214]IfEG3NsBfGhtbCalasoF/44kyLyQDdBE36XFV8raJP/IqPqGXJS65vkqj14marJ/ghULf++zhqbyHOZEzhjac+3HqDjBUVLw32g/sLudTheZh/7lC/8KgRiEbuCht+95ELS4oJ3gZeev4RIEZYxf/w==[/tex]按式[tex=9.429x1.357]jILah2cHpe8RVf0EOgsJD6FDoJNNgxVNdQ8J1ro2qrwFwzMDodpuanRRRXx5MAiV[/tex]绘出该刚架的弯矩图如习题解答图 [tex=3.571x1.357]2KVX8FVhM83mnnDDvkTO3A==[/tex] 所示。