Abstract: Spatial steel structure has various forms and beautiful shapes. It is a structure with three-dimensional shape and three-dimensional stress characteristics. However, with the improvement of construction technology, there are many steel structures with great difficulty in installation and construction, such as special-shaped columns, variable elevation space trusses and long-span trusses, showing the characteristics of long span and complex stress. Taking a long-span unequal height truss roof of Nanyang South Railway Station as the carrier, the construction technology of unequal high-span space truss is complex, and there is a large cantilever span, which produces large deformation and high stress on its lower V-shaped column. From the perspective of the project itself, the project is a spatial inverted triangular steel truss structure with a cantilever part of 25 m, which belongs to a long-span cantilever structure. According to the analysis of structural stress, the stress of long-span cantilever structure is unfavourable. Firstly, under the action of vertical force and horizontal force, the bending moment and shear force at the root of the cantilever are large, and the stress of the node at the root is complex, which is easy to become a weak point. Once it is damaged due to large stress, the whole structure will form a mechanism, resulting in the collapse or overturning of the whole structure. Secondly, the cantilever structure is very sensitive to vertical earthquake resistance. If the cantilever length is large and the cantilever part is self significant, this effect will be very obvious. Third, the overall stability of the cantilever structure is poor, so it is necessary to check the overturning resistance of the structure and take some targeted balance measures.
Considering the scheme suitable for the project, the conventional sectional hoisting method should be adopted, which has the advantages of strong operability and high safety factor. The high-altitude welding quality can also be controlled through targeted measures to ensure the project quality, as well as the simulation analysis of finite element software in the construction process, the simulation of three-dimensional dynamic model used in the hoisting process, real-time interference detection, so as to ensure that the components are installed in place, and the construction scheme can be optimized in time to ensure construction safety and construction efficiency. Therefore, the main research contents of this paper:use MIDAS analysis software to simulate the construction process of V-shaped column with high-altitude scattered assembly, so as to ensure the safety and efficiency of subsequent construction; ANSYS analysis software is used to calculate and analyze the key connection points of V-shaped column, and then corresponding reinforcement measures are taken to ensure the safety and quality of the project.
The results show that:1) the structural stress changes gradually from 8.65 MPa to 31.9 MPa during column assembly, which is located at the bottom of column foot and in elastic working state. 2) In the column assembly process, the maximum structural deformation is located in the cantilever area, and its value is 9.54 mm, which is less than the specified limit of deflection, and the stress is 31.9 MPa, which meets the requirements. 3) In the process of column splicing, the maximum deformation value and maximum stress are generated in the assembly process of column cantilever area. After structural strengthening, the joint stress and deformation can better meet the design criterion of "strong joint and weak member".