由公式As?A's?N(?ei?h?a's)2f'y(ho?a's)704.8?103?102.13'??277.7mm2??minA?0.002?(100?800?2?300?150)?340mm2360?(760?40)3种内力 Ⅲ、 求解第○
⑴求ei、η、e
M360?106e0???300mm
N1200?103h800??26.67mm?20mm 3030ea?26.67mm
ei?e0?ea?300?26.67?326.67mm
?1?0.5fcA0.5?14.3?170000??1.03?1.0 3N1200?10?1?1.0
l0h?6800?8.5?15，?2?1.080012?l0???1?????ei?h?121400h01?8.52?1.0?1.0326.671400?760?1.12?1.0?1?
??1.12
e??ei?h2?as?1.12?326.67?（2）判别大小偏压
800?40?725.89mm 2N?1200KN?Nb?1206.5KN
??N??1fc(b?b)hf'f?1fcbh01200?103?1.0?14.3?300?150??0.512
1.0?14.3?100?760
由公式 As?'Ne??1fcbx?h0?0.5x???1fcbf?bhfh0?0.5hf''???'?150)2f'y?h0?a's?1200?103?725.89?1.0?14.3?100?389.2?(760?0.5?389.2)?1.0?14.3?300?150?(760??360?(760?40)'?446mm2??minA?0.002?(100?800?2?300?150)?340mm2综合Ⅰ、Ⅱ、Ⅲ 算得的As结果知 钢筋的配筋至少要使As?As'?828mm2 故选用
，As?As'?982mm2