单选题
图示结构中,杆a的轴力N
为下列何值?

- A.N<img src="https://timg.fentiku.com/97/2016/12/22/Nf6dfbrzjC.png" title='Nf6dfbrzjC.png' alt='Nf6dfbrzjC.png'/>=0
- B.N<img src="https://timg.fentiku.com/97/2016/12/22/NFroDlhphh.png" title='NFroDlhphh.png' alt='NFroDlhphh.png'/>=P/2
- C.N<img src="https://timg.fentiku.com/97/2016/12/22/VTf8RDgD9w.png" title='VTf8RDgD9w.png' alt='VTf8RDgD9w.png'/>=P
- D.N<img src="https://timg.fentiku.com/97/2016/12/22/6K31z5MvHc.png" title='6K31z5MvHc.png' alt='6K31z5MvHc.png'/>=3P/2
正确答案:D
