本研究主要發展預力梁結構的反算方法，用鋼腱與混凝土梁之間的諧和變形來模擬預力梁撓動行為，並結合梁體的初始預力狀態反算預力。分析模型使用Euler-Bernoulli梁，研究將預力梁分成預力加載階段及外力加載階段，首先預力加載階段探討鋼鍵施拉對混凝土的預拱變形，外力加載階段探討鋼腱錨錠後，梁體受外力作用，透過混凝土梁變形影響鋼腱曲率，讓鋼腱預力狀態改變，間接使梁的受力狀態不同而影響變形。同時也探討外力加載階段的動態反應，將梁初始內力狀態放入頻率方程式，建立頻率與預力關係。若上述方法未考慮初始預力狀態，則要使用等效勁度法將梁體加勁，來達到預力反算的目的。

This research develops the inverse calculation method of existing prestress in a PC beam. Simulate the prestressed beam vibration by compatibility of deformation between steel tendon and concrete beam. and the prestressed force is calculated by the initial prestressed state of the beam. The analysis model uses the Euler-Bernoulli beam to simulate the prestressed beam in-to the pre-loading phase and the external loading phase. Firstly, the pre-loading phase is used to investigate the camber deformation of the tendon by the steel in bonded, and the external loading stage is used to discuss the steel in camber. The external force applies on the beam, and the deformation of the concrete beam affects the curvature of the steel tendon, and the tendon state will be change, which indirectly causes the pre-stress state of the beam to be different and affects the deformation. At the same time, the dynamic response of the external loading stage is also discussed. The initial internal force state of the beam is placed into the frequency equation to establish the relationship between frequency and prestressed force. If the above method does not consider the camber state, the equivalent stiffness method is used to stiffen the beam to achieve the purpose of pre-force backward calculation.

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