Abstract: The floating office project of Hunan Radio and Television Station is a large plane multi-layer truss structure supported by multiple tubes. At present, the conventional in-situ construction scheme for the structural system requires a huge amount of measures and a long installation cycle, if the overall lifting construction scheme is adopted, the structure separated from the core tube is separated into several truss units, it is difficult to construct. For the above problems, a ring hoop reinforcing tooling system and a complete set of lifting structure deformation and closing precision control technology were developed, the discrete truss units were converted into integral structural system with sufficient lateral and torsional stiffness, which was satisfied for lifting construction and precise closure, at the same time, the mechanical characteristic of the whole lifting structure system were described and the mechanism in the overall lifting state was revealed.
The research contents and conclusions include:1) Through in-depth analysis of core tube and cantilever truss monomer synergistic effect mechanism, the ring hoop reinforcing tooling system is designed to replace the restraint and force transmission of the original core tube, provides sufficient strength and stiffness in the overall lifting state, the multiple scattered truss monomer can meet the overall lifting construction requirements after reinforcement; 2) Finite element software MIDAS-Gen is used to study the force transfer mode and mechanical characteristics of the ring hoop reinforcement tool system in lifting state, it is further optimized as a mechanical system of carrying pole girder composed of lifting point and bottom beam. The cantilevered trusses at both ends of the carrying pole girder are self-balanced to some extent, although the structure system is simplified, the force transmission path is more direct, the functions of vertical rod force transmission and horizontal rod stiffness control are given full play. According to the comparison analysis of finite element calculation results, compared with the ring hoop reinforcement tooling before optimization, the vertical deformation of the cantilever ends of the lifting structural system is reduced by 10%~12% after optimization, it is more advantageous to control the deformation of the whole structure, and the lifting point is optimized by half, the synchronization of structural lifting is easier to ensure, the measure quantity is optimized by about 30%;3) After lifting the floating office in place, there are 120 seams, its closed precision is the decisive factor for the construction quality control of floating office in the south area. Finite element software MIDAS-Gen is used to calculate and analyze the deformation trend of floating truss structure in lifting state and the regularity of the staggered joints of the closure. It is found that reverse pre-adjustment of the key points of the cantilever end of the lifting unit in the assembly phase can effectively ensure the closing and the overall forming accuracy of the structure; 4) Through the deformation monitoring of floating truss structure from assembling to closing, it is found that the variation trend of the measured relative deformation is basically consistent with that of the result of construction simulation calculation, no excessive structural deformation occurred during lifting and unloading, the reliability of the ring hoop reinforcement system and the complete set of deformation of lifting unit and closing precision control technology are verified.