【摘要】 本文通过两批模型试验和若干工程的实践，说明了混合配筋的预应力混凝土框架扁梁长期挠曲（即反拱和挠度）变形的规律性不同于传统的观念。文中提供了任意受力状态下，混合配筋截面的构件长期挠曲系数σ（t，τ）的计算方法；并用该系数反映长期挠曲的变化规律。通常θ（t，τ）＝＋3～－3．5。这种特殊的规律性（即长期反拱可增长、持平或下降的规律性）在框架扁梁楼盖结构形式中显示得更加敏感和突出，应当引起注意。更多还原

【Abstract】 Through two 1/3 scale model tests and several construction projects, it has been noticed thatthe variation regularity of long-term fie-cure (camber and deflection) of prestressed concrete frameshallow-beam with composite reinforcement of nonprestressed steel and unbonded tendons isdifferent from the traditional behavior. This paper presents a method for calculating the long-teflexural factor 8(t, r ) which is adaptable to prestressed concrete member reinforced withnonprestressed steel and unbonded tendons subjected to arbitrary forces. The fie-cural factor 0(t, r)reveals the variation regularity of long-term fie-cure with its value lying between + 3 and-3. 5.This phenomena, i. e. the long-term camber produced by pure prestressing may increase, keepconstant or even decrease as time goes on, is quite sensitive in frame shallow-beam floor systemwith nonprestressed steel and unbonded tendons. It should be well noticed in design.更多还原