Study Of The Bidirectional Truss String Structure Test Of Cable Tension Based On Half-wave Method

The bi-directional beam string structure is a kind of prestressed structure to which cable stability is of core important.Cable tension is important in assessing the safety of such structure and predicting the performance and life of the structure.The cable in bi-directional beam string structure is two-way and has multi span.For the cable is constrained by the strut,the adjacent cable and the intersecting cable and the boundary condition is very complicated,identifying cable force may meet difficulties.In order to accurately identify the cable force of the bi-directional beam string structure,half wave method has been studied.The stress characteristic of the test model and the working condition of the cable are studied via cable teat,numerical simulation and theoretical analysis of bi-direction beam string model.On this basis,the modal information of the cable to be measured is obtained.Then we use frequency method and half wave method to calculate the cable force of the modal.Half wave method is verified useful in bi-direction beam string structure in actual project.The cable,the deflection and the axial force of the strut at both ends of the model have the spatial symmetry.The stress characteristic of the model conforms to actual bi-direction beam string structure,and cable working condition is in accordance with design concept.So it can be inferred that the model meets the requirement of the test.In bi-direction beam string structure,the boundary condition is very complicated,and the dynamic behavior is changing,great errors may occur,if we simply consider it as hinged constraint and use the frequency method to identify cable force.While half wave method can identify the cable force via vibration of local cable,which can avoid the influence given by complicated boundary condition.The cable force calculated by high-order modal information is more accurate than that calculated by lower order modal information.When the vibration mode increases,the little local cable will be influenced by the complicated boundary condition,the more accurate cable force will be if half wave method is used.