混凝土构件延性系数最通用的表达式为极限曲率φ_u 与开始屈服时的曲率φ_y 之比。式φ_u/φ_y 可根据基本原理计算。延性系数随截面的几何形状、钢筋配置、荷载以及钢筋和混凝土的应力-应变关系而变化。下述确定已知截面延性系数的方法,在很大程度上能满足设计需要。一、单筋截面考虑截面开始屈服和达到极限弯矩时的情况如图1所示。 The most common expression for the ductility coefficient of a concrete element is the ratio of the ultimate curvature φ_u to the curvature φ_y at the beginning of yield. The formula φ_u/φ_y can be calculated based on the basic principle. The ductility coefficient varies with the geometry of the section, the configuration of the rebar, the load, and the stress-strain relationship of the rebar and concrete. The following methods for determining the ductility coefficient of a known section can, to a large extent, meet design requirements. First, the single-bar section considers the situation when the section begins to yield and reaches the ultimate bending moment as shown in Figure 1.