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非线性阶段次弯矩的演化,以及承载力极限状态下是否考虑次弯矩的问题一直存在争议。为解决这一问题,拓展了预应力次弯矩的概念,使其能够适用于非线性阶段。运用变刚度法数值模拟了初始次弯矩(M2)与弹性最大荷载弯矩(Me)之比为0.15~0.36的15根有黏结预应力混凝土两跨连续梁。基于拓展后的次弯矩概念,提出了以混凝土受压区相对高度、初始次弯矩与弹性最大荷载弯矩之比为影响参数的有黏结预应力混凝土连续梁弯矩调幅公式。采用已有文献中受压区相对高度为0.35的试验梁比较了所提公式和现有的弯矩调幅公式。设计制作受压区相对高度为0.18的两跨预应力混凝土连续梁,获取单调加载下支座反力数据,检验了内力重分布程度较大时所提公式的效果。结果表明,给出的弯矩调幅公式的计算结果偏于安全,且更接近试验结果。
The evolution of moment of non-linear phase and the question of whether to consider the moment of second moment in the limit state of bearing capacity have been controversial. In order to solve this problem, the concept of prestressed secondary moment has been extended to make it suitable for non-linear phase. The variable stiffness method is used to numerically simulate 15 prestressed concrete two-span continuous beams with a ratio of initial secondary moment (M2) to elastic maximum load moment (Me) of 0.15-0.36. Based on the extended secondary moment concept, a formula of bending moment modulation of continuous concrete beams with bonded prestressed concrete is proposed based on the parameters of the relative height of compression zone, the initial secondary moment and the ratio of elastic maximum load moment. In the existing literature, the test beam with a relative height of 0.35 in the compression zone is used to compare the proposed formula with the existing formula of moment modulation. Design and manufacture of two-span prestressed concrete continuous beam with a relative height of 0.18 in the compression zone to obtain the reaction force data under monotonic loading, and test the effect of the formula given when the internal force redistribution is large. The results show that the calculated results of moment modulation formulas are biased towards safety and closer to the experimental results.