Research On Structural System Of Self-balancing Prestressed Steel Structure Static Load Test Loading Device

Aiming at the static load test of the new 40 m span prestressed concrete simply supported beam box girder of high-speed railway,this paper studies the large-span combined force structure system combining steel structure and prestress.The structure is designed by the self-balancing principle of closed force system.The test process does not increase the foundation and foundation bearing burden,clear transmission force,simple structure,low steel consumption,and large structural rigidity.In this paper,the finite element software Midas/civil is used to simulate the stress state of the loading device,and the reasonable structure selection and design parameters are determined by comparison calculation and experimental test.The main design contents include: the determination of the height,the choice of the structure of the upper chord,including the choice of single or double string,curved rod or folding rod,the selection of the connection structure of the upper chord and the steel box beam,and the reasonable control tension of the steel strand tension Select and so on.After a large number of calculations,the structural structure is determined and the parts are strengthened to meet the force and force requirements.Then,the three-dimensional Simulation calculation and analysis of the key parts with complex forces,such as anchor boxes and special nodes,are carried out to further verify the safety and reliability of the design structure.Finally,the field measured data is compared with the theoretical calculations to draw conclusions.The results show that the total height of the structure is determined to be 5.125 m in order to meet the requirements of road transportation boundary on the basis of ensuring the bearing capacity of the structure.The upper chord is in the form of a double-chord folding line,the steel strand is threaded out from the center line of the end face of the steel box beam,and the outer control force of the single-strand steel strand anchor is taken as 2 688.7 kN.Through seven-stage tensioning and nine-stage loading measurement,it is proved that the structural strength,stiffness and stability can meet the specification requirements under tension and test loading conditions,and have sufficient safety reserves.