圖示結構當高度增加時,桿①的內力將:()
A.增大 B.減小 C.保持非零常數(shù) D.保持為零
圖示兩桁架結構桿AB的內力分別記為N1和N2。則兩者關系為:()
A.N1>N2 B.N1 C.N1=N2 D.N1=-N2
圖示桁架結構桿①的軸力為:()
A.-2P B.-P C.-P/2 D.P