A.σa增大,F(xiàn)‘應(yīng)適當(dāng)減小 B.σa增大,F(xiàn)‘應(yīng)適當(dāng)增大 C.σa增小,F(xiàn)‘應(yīng)適當(dāng)減小 D.σa減小,F(xiàn)‘應(yīng)適當(dāng)增大
A.直徑小,易過載 B.直徑小,不易控制預(yù)緊力 C.直徑大,材料缺陷多 D.直徑大,安全
A.480MPa B.6MPa C.8MPa D.0.8MPa