A.70% B.75% C.80% D.85%
A.提高預(yù)應(yīng)力筋的屈服強(qiáng)度 B.拉直預(yù)應(yīng)力筋 C.使每根預(yù)應(yīng)力筋的應(yīng)力一致 D.減小預(yù)應(yīng)力損失
A.C25 B.C30 C.C35 D.C40