F1180.5 n F =3.47>n 51.96 ②杄的稳定性: 32 1,800 =8mm, =100 4 i18 2÷z2E2 F =158.7kN 2158.7 F5196 =3.05>nxt 2 满足稳定要求s t cr n F F n = = = 3.47  51.96 180.5 1 1 1 ②杆的稳定性： P i l i m m   = =  = = =100  8 800 8 , 4 32 1 1 1 2 1 k N l EI Fcr 158.7 ( ) 2 2 2 2 2 2 = =   s t cr n F F n = = = 3.05  51.96 158.7 2 2 2 满足稳定要求