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Guo Yanlin, a professor and doctoral supervisor at Tsinghua University, was awarded the second prize of the National Science and Technology Progress Award (General Project) in 2011 for his research achievement on key technologies for time-varying analysis and control of complex steel structure construction processes and engineering applications, which was completed as the first author. Famous steel structure expert Cai Yiyan in China once said, "Guo Yanlin has many innovative projects in the field of steel structures, and his level of innovation is also very high. He has participated in research on projects such as the National Stadium and the Guangzhou New TV Tower, and has raised the technical difficulties encountered in the engineering to the level of theoretical expansion for research." Guo Yanlin, who started teaching in 1988, has been around the world. His students include general managers or chief engineers of enterprises, as well as staff from industry regulatory departments. Most importantly, they are all active in the current steel structure industry, and together with their teacher Guo Yanlin, they are tirelessly striving to become a steel structure powerhouse in China. This newspaper will publish an article titled "Research and Engineering Application of Key Technologies for Time Varying Analysis and Control in the Construction Process of Complex Steel Structures", which won the second prize of the 2011 National Science and Technology Progress Award (General Project), in two installments. Please stay tuned—— editor

The theory of construction mechanics calculation and construction control technology are developed synchronously with the construction of large and complex steel structures. At present, the large and complex steel structure engineering projects that have been built or are under construction in the world are mainly concentrated in China, and their construction mechanics calculation theory and construction control technology have always been the key challenges to be solved in engineering construction. The research group on key technologies for time-varying analysis and control in the construction process of complex steel structures (hereinafter referred to as the research group) has gradually established and improved an integrated collaborative time-varying analysis system and calculation theory for the construction process of large-scale complex steel structure engineering projects in China. It has solved the key technical problems of controlling the shape and force of time-varying structures during construction, and promoted the leapfrog development of mechanical calculation theory and construction control technology for complex steel structure construction in China.

1、 Establishment and application of an integrated collaborative time-varying analysis system for complex steel structure construction processes

We have established an integrated collaborative time-varying analysis system and calculation theory for complex steel structure construction processes, addressing issues such as the discontinuity of construction and the interaction between various parts of the construction system in previous simulation calculations. By integrating existing technologies such as life and death elements, as well as new technologies such as state nonlinear solving techniques established by the research group, adaptive algorithms for cable pulleys, jack contact elements, and point by point unconstrained shape finding methods, the gradual installation of permanent components, assembly and removal of temporary supports, appearance and disappearance of temporary construction loads, and the effects of temperature and wind loads during the construction process are integrated, which can truly reflect the time-varying characteristics of structural installation, boundary conditions, load effects, and material properties; Especially adept at accurately analyzing the evolution of construction systems in time and space domains, accurately calculating the interactions between various parts of the construction system, and accurately grasping the continuous changes and nonlinear accumulation process of internal forces and configurations of the structure during the construction process.

The research group has established a multi-stage comprehensive iterative method for the calculation of three-dimensional dynamic deformation pre adjustment values during the construction process of structures with particularly complex construction paths and deformation development processes. This effectively solves the problem of pre adjustment value calculation for the deformation of the main building of the new CCTV site and the new Guangdong Provincial Museum.

We have established a digital and information application technology for accurately evaluating construction plans and structural safety during the construction process by effectively integrating digital simulation computing technology into new construction technologies such as overall structural lifting, overall lowering, overall sliding, overall tensioning, and overall lifting.

In the overall improvement of construction technology, a safety guarantee mechanism for the lifting system has been formed to prevent potential damage risks to the lifting structure and tire frame caused by different stress situations in the design and lifting states; A reasonable distribution mechanism for lifting force has been formed, which can automatically control the complex distribution relationship of the total lifting weight between the structural columns and the lifting tire frame; A fully time-varying control mechanism has been formed, achieving a seamless connection in the digital simulation analysis of the lifting process of the lifting structure, such as detachment from the tire frame, lifting, closing, and falling. The complex interaction mechanism between the lifting structure system and the supporting structure system has been revealed, and automatic analysis and evaluation of lifting point displacement asynchrony, special situations such as collision and cable breakage during the lifting process, as well as load conditions such as wind load and temperature effect, can be achieved in an overall finite element analysis model.

Accurate active control of the interaction forces between the sliding structure and the sliding support system at different positions and construction steps has been achieved in the overall sliding construction technology; In the overall scaffolding construction technology, precise analysis of the effects of contact, detachment, re contact, and mutual displacement between the structure and the tire frame has been achieved, solving the distortion problem previously analyzed using the support displacement method; In terms of overall tensioning construction technology for tensioned structures, seamless connections have been achieved through initial pre-stressed state shape finding analysis, tensioning process analysis, and analysis of action effects during use, filling the computational technical deficiencies of cable structures for large displacements and complex boundary conditions; To meet the installation needs of giant steel arches and giant circular steel structures, we propose a comprehensive adaptive integral lifting construction scheme and integrated modeling collaborative time-varying analysis technology; The state nonlinear solution technology, dynamic configuration solution technology, point by point unconstrained shape finding analysis method, and new technology of pseudo pulley and movable cable pulley unit for structural lifting were proposed for structural analysis during the construction process. A construction plan optimization technology based on time-varying analysis was established, effectively solving the problem of nonlinear changes and cumulative simulation analysis of time-varying structural internal forces and configurations during the construction process. (To be continued)