非线性阶段次弯矩及其演化规律试验研究

采用基于割线刚度的等效线性化方法拓展了次弯矩概念,使其能够运用于非线性阶段。进行了4根无粘结预应力混凝土两跨连续梁受力全过程试验。研究结果表明,运用等效线性化方法可以将连续梁非线性阶段的支座反力分解成为预应力等效荷载引起的以及外荷载引起的两个部分,从而分离出次弯矩和外荷载弯矩。非线性阶段,无粘结预应力连续梁的次弯矩随预应力筋拉力的增长而增长。次弯矩折减系数随中支座截面受压区相对高度的增大而增大。承载力极限状态,非线性次弯矩在数值上大于初始次弯矩。

EXPERRIMENTAL STUDY ON SECONDARY MOMENT AND ITS VARIATION IN POST-ELASTIC RANGE

Secondary moment concept is extended into post-elastic range by an equivalent linearization method using secant stiffness. An experimental study is conducted on four prestressed concrete continuous beams with unbonded tendons over entire loading. The results show that by an equivalent linearization method, the support reactions of a continuous beam in nonlinear stage can be decomposed into reactions due to tendon equivalent loads and to external forces, thereby separating the secondary moment and external load moment. The nonlinear stage secondary moment increases with the growth of tension in unbonded tendons. The reduction factor of secondary moment increases with the relative height of the compression zone of the section at an inner support. At the ultimate limit state, a nonlinear stage secondary moment may be greater than the initial secondary moment.