Study On Actual Stress Of High-strength Steel Wire In Existing Prestressed Concrete Hollow Slab-bridge Based On Frequency Method

Actual prestress of prestressed concrete structure is one of the important indexes which is used to evaluate the existing situation of existing prestressed concrete structure. The loss prestress will affect properties and durability of the prestressed concrete structure,and even cause safety accidents of the structure. Prestressed reinforcement as the main part of prestressed concrete, acculate testing actual prestress on prestressed concrete structure has an important significance to evaluate the existing situation of the prestressed concrete structure. At present, we mainly though the theoretical formula calculate the actual prestress of prestressed reinforcement, but have not seen the literature on testing actual prestress of reinforement.As a prestress test method, vibration-frequency method is mainly used in the detection of cable force, and obtained a certain result. In this paper, cable force measurement by frequency method is studied, so I think that it may be used to measure the actual prestress of prestressed steel wire, and study on using frequency method to analyse the actual prestress of prestressed steel wire in the hollow slab-bridge, and main achievements are:(1) Based on analysing the transverse vibration characteristics of high-strength prestressed steel wire, the theoretical formula of high-strength prestressed steel wire tension and frequency is deduced by decomposition method. It provides theoretical preparations for using frequency method to measure actual prestress of prestressed steel wire.(2) Based on studying on the factors which affect the measurement of frequency of high-strength prestressed steel wire, will not ignore factors which is concidered in the theoretical formula, and provides the basis for measuring accurately the frequency of high-strength steel wire.(3) Through the comparison between experiment data curve and theoretical curve, the shortest length is confirmed, that is suitable for measuring actual prestress of high-strength steel wire.(4) Through the experiment date fitting, we get the modified coefficient and confirm the modified formula which is applied to measure actual prestress of prestressed steel wire in the hollow slab-bridge.