A、<img width='109' height='21' src='/s/tiw/p3/UpLoadImage/2013-05-07/fbef80dd-dc59-4457-a27f-55df676518cb.png'>
B、<img width='228' height='37' src='/s/tiw/p3/UpLoadImage/2013-05-07/781ad160-93ef-441b-9c95-c40ab92d5a65.png'>
C、<img width='231' height='34' src='/s/tiw/p3/UpLoadImage/2013-05-07/90a8281d-98c1-4d86-9a99-4e51a125e4cf.png'>
D、<img width='232' height='34' src='/s/tiw/p3/UpLoadImage/2013-05-07/3c1fd6c6-9989-446e-a4a6-dc1c5c23ee97.png'>
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试题解析
对A点列力矩平衡方程∑M
A=0,即
![](/s/tiw/p3/UpLoadImage/2013-05-07/fca97aa9-30ff-447f-b47d-680205fffbf9.jpg)
,从而可得
![](/s/tiw/p3/UpLoadImage/2013-05-07/e595a89d-6225-4792-9442-e098d6bbdc04.jpg)
,方向向下,再根据简支梁竖向力平衡∑F
y=0,F
B+F
A=0,解得
![](/s/tiw/p3/UpLoadImage/2013-05-07/3f80d016-1916-4a74-a21c-01f0846ada92.png)
方向向上。