Research On Optimal Selection Of Super-large Span Mega-latticed Structure

With the continuous improvement of science and technology and the requirement of material and culture,there is a growing demand for large span buildings with diverse functions.Engineers also have been working hard to explore new structural systems and strive to make greater breakthroughs in enhancing the span capability of buildings.Kiewitt type mega-latticed structure has been proved to have good mechanical and economical performance at the span of 800 meter,so it deserves further study whether other forms of mega-latticed structures perform equally well and the mega-latticed structure is suitable for larger span or not.In this paper,based on the molding method of the spherical mega-latticed structure and combining with the geometric topological relations of the single-layer spherical reticulated shell,five kinds of super-large span mega-latticed structure models were established,such as Ribbed type mega-latticed structure.Under the three span of 800 meter,1000 meter and 1200 meter,the mechanical and economical performances of each mega-latticed structure were contrasted to select excellent overall structure schemes under each span.The key parameters of the reasonable mega-latticed structure under the span of 1000 meter were systematically analyzed,and the rationality of adding the internal support to the mega-latticed structure was preliminarily explored.The main contents are as follows:First of all,the geometric topological relations of five kinds of spherical reticulated shells which contain Rib dome,Schwedler dome,Sunflower dome,Three-dimensional grid dome and Geodesic dome were analyzed.Combined with the molding idea of the spherical mega-latticed structure,the automatic generation program of five kinds of super-large span mega-latticed structures,such as Ribbed type mega-latticed structure,was compiled.The reasonable finite element calculation parameters were selected,and the corresponding super-large span mega-latticed structure models were established.Based on the principle of full stress design and mechanical characters of the mega-latticed structure,the optimization method of member section according to the location and classification of components was put forward.On the basis of the above work,the static and economical indexes of mega-latticed structures which contain the above five kinds of super-large span mega-latticed structures and Kiewitt type mega-latticed structure under the span of 800 meter,1000 meter and 1200 meter were calculated,and the force law of the mega-latticed structure was summarized.Considering the static performance and economical indexes,the reasonable schemes under different spans were obtained.The effects of the four key parameters,such as rise-span ratio,on the mechanical property of Geodesic type mega-latticed structure and Three-dimensional grid type mega-latticed structure under the span of 1000 meter were studied.The changes of the mechanical and economical performance with the variation of the parameters were summarized,and the reasonable range of each parameter was obtained.At last,corresponding research on adding internal support to the mega-latticed structure has been carried out to further promote the engineering application of the mega-latticed structure.The indexes which can reflect the static performance of the mega-latticed structure after adding inner support were selected.A reasonable internal support plan was obtained by comparing and analyzing a variety of support schemes,and the method to find reasonable inner support location was proposed.The reason why the static performance of the structure changed after the addition of inner support was explained,and the mechanical and economical indexes of the mega-latticed structure after the addition of inner support were calculated.