Analysis And Application Of Construction Mechanics Of Long-span Steel Structures

The application of construction mechanics in long-span steel structures has become a hot topic in today's civil engineering and academy arena. To conduct research in this topic, it is necessary to have a clear understanding of its mechanics fundamental– time-varying mechanics. Based on previous works, focusing on solving practical problems, combining with field monitoring data, the author carried out some study in the topics and applied the methodology of construction mechanics during a long-span steel structure construction project with good results. My work, reported in this article, can be summarized as follows:1. The characteristics and classifications of construction mechanics are described; construction mechanics research topic and its effect are also summarized and discussed. Theoretical foundation of construction mechanics is the main subject of my study, with focus on time-varying mechanics and basic methods and characteristics in mechanical construction. Basic equations and the finite element method formula of relative time-varying mechanics problems are also given.2. Mechanical numerical analysis, features and the significance of time-varying parameters in the construction of long-span steel structure are discussed. Taking the difficulty of analysing time-varying of structure geometry and boundary conditions into consideration, based on segment installation practice and the pre-angle concept in nodes installation,"life and death"sub-structures are proposed and subject to the process of individual solving. A construction method simulation based on adjustment of node rotational constraint was developed, from which"life and dead"substructure finite element matrix equations are proposed and proved to be correct and accurate by calculation of some typical examples and engineering analysis in actual construction project.3. Based on stress and deformation data collected during construction phase and after building put to service, the pressing force characteristic of Shenzhen Convention and Exhibition Centre (SZCEC) steel structure and its bottom chords steel bars were used in in-deep construction mechanics calculation and analysis according to the methodology as described in this article. With consideration of geometric nonlinearity, scaffolding support and lower scaffold, a variety of loadings were used to run simulation to determine structural stress and deformation. Three sets of data and their variation patterns were also analysed to determine correlations among processing paths of removing scaffold. Conclusions are derived from the above analysis process, which could be useful for future design and construction process. 4. Beam string structure form finding belongs to problems in construction inverse solving. Problems associated with temperature reduction in large deformation, initial strain method simulation, prestress application and variations in element stiffness and stress were discussed. A correction methodology for the related stress and stiffness is proposed. Using the concept of preload force in mechanical structure components, an effective method for simulation of beam string pretension was established to overcome the above problems. The new method was also tested through several classical numerical examples and proved to be effective.5. Based on the characteristics of big influence of beam string structures depending on the rotation of bracing member, minimal rotation of bracing member is the objective of optimization. Beam string pretension construction plan optimization was also discussed, and the optimization algorithm of linear forecasting-nonlinear correction was presented. Numerical examples show the effectiveness of the method and three sets of pre-tention plan were studied. The method will be useful in practical structural design and construction.