Mechanical Behavior of Reinforcing Steel and Design of Concrete Structural Members

对市场上的预应力筋（特别是钢筋）的应力-应变关系的形状进行了研究。通过3种配筋率的预应力混凝土梁受弯试验，研究了不同配筋率下预应力混凝土梁的应力-应变关系对预应力混凝土梁受力性能的影响。研究了气压焊不充分对普通钢筋的影响。主要结论如下：（1）JSCE《混凝土结构设计与施工标准建议》对1号和2号预应力筋的应力-应变曲线采用了不同的理想化模型，而采用热处理方法制作的1号和2号预应力筋的应力-应变曲线几乎相同。2）预应力筋的配筋关系对弯矩-曲率关系的影响较大，对荷载-挠度关系的影响较小; 3）当含钢率增大时，预应力筋不屈服，混凝土发生破碎; 4）气压焊不充分对梁试件静载下的弯曲破坏行为影响较小。

The shape of stress-strain relationships for pre-stressing tendons (especially on bars) available in the market were examined. Flexural tests of beam specimens with three kinds of steel ratios were carried to study the effect of the stress-strain relations on the mechanical behavior of pre-stressed concrete beams. The effect of inadequate gas pressure welding to ordinary reinforcing bars was also investigated. Principal conclusions derived are as follows ;1) Different idealized models of stress-strain curve for No.1 and No.2 pre-stressing bars are shown in the Standard Recommendation for Design and Construction of Concrete Structures of JSCE.The curves for No.1 and No.2 bars, however, were found to be almost the same when the bars were made by the thermo-treated method. The expression of the curve in the Standard must be changed.2) Moment-curvature relationship, and hence load-deflection relationship, is affected largely by the relation of tendon, but slightly by that of concrete.3) When the steel ratio became larger, yielding of the tendon did not occur and concrete crushed.4) Inadequacy of gas pressure welding slightly affected the flexural failure behavior of beam specimens under static loading.