Research On The Lifting Points Location Of Large-span Steel Structure

The large-span steel structure is widely used in public buildings and industrial buildings with the development of the steel structure technology. The increase in span and complexity of steel structure can promote the development of installation technology. In recent years, large and even super hoisting capacity cranes are coming into service in the construction of large-span steel structure, thus the integral lifting technology is shining. At the same time, many key technology problems including the lifting points location arise day after day.The problem of lifting points location consists of determining the number of lifting points and distributing them. The feasible but poor scheme of lifting points location may cause construction cost to unnecessarily increase. In more advanced cases, the structure may become failure in the process of hoisting. So, it’s meaningful that to study the problem of lifting points location of large-span steel structure.The comparison among the minimum bending moment criterion, the stress radio and deflection criterion and the theorem of minimum strain energy are carried on, and some advice on the scope of application of each criterion are given.An improved evolutionary programming with bi-group and single-point mutation has been put forward. The programs based on improved evolutionary programming and particle swarm optimization are developed by MATLAB to optimize the location of lifting points, among which the theory of minimum strain energy is mentioned and the secondary development technology of ANSYS-APDL is used and ANSYS is called in background during the optimization. Then taking a grillage girder as an example, the performance and efficiency of the algorithms in different optimization ideas (hiberarchy optimization and synchronic optimization) and different optimization methods (the particle swarm optimization and evolutionary programming) are compared, the results indicate that the improved evolutionary programming method based on synchronic optimization idea is satisfactory and provides a new but more effective method.The rule of lifting points location of flat-panel grid structure is further studied. By comparing the results of strain energy model and that of stress radio model, it identifies that the stress radio model is more applicative for flat-panel grid structure in optimizing the location of lifting points. The results coming from single factor analysis indicate that different form of structure has a little effect on the location of lifting points, and the lager the span of structure is, the more lifting points are needed. At last, the project cost is combined with lifting points location in this paper, and the mathematical model has been built. According to the characters of the problem, two different resolution strategies, which called the strategy based on crane and the strategy based on structure respectively, are given, and it’s useful in formulating construction plan.