第四題
(一)`L_b`=40/3=13.33ft
`=>L_p<L_b<L_r`
`M_p=Z*F_y`=107*50=5350K-ft
`M_r=F_L*S_x`=(50-10)*93=3720
`M_(max)=133.33,M_A=33.33,M_B=66.67,M_C=100`
`C_b=(12.5M_(max))/(2.5M_(max)+3M_A+4M_B+3M_C)=1.667`
`M_n=C_b*[M_p-(M_p-M_r)*(L_b-L_p)/(L_r-L_p)]`=6788.513
(二)翼版
`Lambda_p=0.38*sqrt(E/(F_y))`=9.152
`Lambda_r=0.83*sqrt(E/(F_y))`=20
`Lambda=(b_f)/(2t_f)`=9.47
`M_n=[M_p-(M_p-M_r)*(Lambda-Lambda_p)/(Lambda_r-Lambda_p)]`=5302.4<`M_p`
(三)腹版
`Lambda=h/(t_w)`=53.6
`Lambda_p=3.76sqrt(E/(F_y))`=90.553
為結實斷面`:.M_n=M_p`
`M_n`=min(5350,6788.513,5302.4)=5302.4K-ft
`phi_b*M_n`=0.9*5302.4=4772.16K-ft
不知道答案對嗎?請各位大大賜教,謝謝
另外,題目給的`L_p`跟`L_P'`有什麼差別呢?
在(一)的部分,是用`L_p`嗎?
