Comparative Study Of Steel And Aluminum Alloy Reticulated Shell Structures Based On Full Life Cycle Cost

The latticed shell structure is mostly used in some public and industrial buildings with large investment scale and large social and environmental impact.The traditional engineering cost method only considers the cost of latticed shell structure in the construction period,but the cost in the use stage and the scrap stage also accounts for a certain proportion.In this thesis,the structural design and mechanical properties of steel and aluminum alloy latticed shells are analyzed.The cost of each stage and the whole life cycle are compared.The better economic structure scheme of latticed shell is optimized to achieve the goal of reducing the life cycle cost of latticed shell,which provides reference for practical engineering design.The main contents and conclusions of this thesis are as follows:(1)The structural models of spherical latticed shell and cylindrical latticed shell with steel support of two kinds of materials(steel,aluminum alloy)and single and double layers,multiple span and rise span ratio are established by using steel structure design software 3D3 S software.The structural design and mechanical properties are compared and analyzed.The results show that the laws of stress ratio distribution,member internal force and natural frequency distribution of steel and aluminum alloy double-layer latticed shells are similar.However,the elastic modulus and density of aluminum alloy 6061-T6 are only 1/3 of that of Q235,the design strength is slightly lower,so the structural performance will be different.(2)Based on the whole life cycle cost theory and combined with the specific characteristics of latticed shell structure,the whole life cycle cost of latticed shell structure is divided into five stages: preparation stage,design stage,construction stage,maintenance stage and removal stage.The whole life cycle cost of latticed shell structure is divided into the cost of each stage above.Based on the existing estimation formula,the whole life cycle cost estimation formula of latticed shell structure is improved by modifying the maintenance cost estimation formula.(3)The life cycle cost of steel and aluminum alloy mesh shell structures is analyzed by using the life cycle cost estimation formula of mesh shell structures.The cost of each stage and the total life cycle cost are compared.The research shows that the construction cost has the greatest influence on the latticed shell structure,followed by the maintenance cost.The maintenance cost of steel latticed shell is always higher than that of aluminum alloy single and double latticed shell.(4)The life cycle cost of spherical latticed shell structure with steel support with different span and rise span ratio is compared and analyzed.The results show that when the span of spherical latticed shells is 40 m,60m and 80 m,the optimal schemes are aluminum alloy singlelayer spherical latticed shell with 1/5 rise-span ratio,aluminum alloy double-layer spherical latticed shell with 1/6 rise-span ratio and aluminum alloy double-layer spherical latticed shell with 1/6 rise-span ratio,respectively.In addition,the structural scheme of spherical latticed shell with better economy is also obtained when span and span ratio are determined simultaneously.(5)Life cycle cost analysis of steel and aluminum alloy double layer cylindrical latticed shell is carried out.The results show that when the span is 80 m,100m and 120 m,the optimal scheme is steel double-layer cylindrical latticed shell.Its life cycle cost is 7.0%,8.0% and 11.9%lower than that of aluminum alloy double-layer cylindrical latticed shell.(6)Through the analysis of life cycle cost of latticed shell structure,it is found that the life cycle cost of aluminum alloy latticed shell is equivalent to that of steel latticed shell in many cases.But aluminum alloy material is not easy to rust,eliminating the heavy anti-corrosion work and the construction effect is better than steel.Therefore,it is necessary to consider the lifecycle cost of the structure,the building effect and the requirements of the owner to determine the appropriate structural scheme.