| Parallel steel strand cable due to technical advantages of its structure and performance, is one of the most frequently used form of cable in cable stayed bridge. Composed of a plurality of steel strands, the cable formation and force distribution are very special compare to the traditional parallel wire cable. The accurate measurement of parallel steel strand cable force is still a problem to be solved. The paper collected, analyzed and summarized the research data of the parallel steel strand, based on the real project, through theoretical analysis, simulation calculation, real bridge cable force monitoring methods, carry on a study of measure of the parallel steel cable force,the main contents are as follows:(1) Comprehensively discussed on the cable types, characteristics, measurement method and current measurement theory. The practice shows that the vibration frequency method is the most convenient way of cable force measurement. Because of the differences between the structural feature of a plurality of steel strand cables and the theatrical hypothesis of the traditional vibration frequency method, putting forward the problems existing and lacks in the process of the direct usage of traditional vibration frequency method in parallel steel cable force measurement.(2) Studied the cable linear vibration theory, took the cable flexural rigidity and sag of cable vibration frequency influence in to consideration, carried on a comprehensive analysis of theoretical calculation method of vibration frequency method, gave the influence factors of error results existing in cable force measurement of parallel steel strand cable when vibration frequency method involved.(3) Identified the parameters which have impact on the cable force of parallel steel strand cable and discussed the discrimination method of the frequency order, analyzed mainly the effect of HDPE sleeve on parallel steel strand, proposed a modifying method of theoretical theory calculation of the cable force when considering the quality of HDPE sleeve and suggestions of frequency order selection.(4) Based on the construction features and cable force influence factors of parallel steel strands, single strand tension control method, modified the cable force measurement theoretical calculation formula of traditional vibration frequency method and obtained the modified calculation formula on parallel steel strand cable force measurement.(5) Using the modified parallel steel strand cable force calculation formula, applied to the cable force measurement relying on the project and analyzed tested cable force and calculated cable force to verify the correctness of the modified formula. |
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