Mechanical Properties And Design Method Of Truss Aluminum Alloy Double Layer Space Grid Structure

Aluminum alloy has excellent properties such as light weight,corrosion resistance,non-magnetic and easy to process.The advantages of its material and geometric system of space structure are combined with each other,so it has a great prospect of development.At present,aluminum alloy single-layer latticed shell and Frentierian double-layered reticulated shell system often produce the whole instability problem when the span is large,so it is difficult to meet the requirements of human activities for long-span building structure in the aspect of economy and safety.Combined with CN 104074265 A patent,this paper presents a truss aluminum alloy bilayer space grid structure,which has reasonable geometric system,simple and efficient joint structure,and has great overall stiffness and span ability.In this paper,the geometric system,the section and the joint structure of the structure are introduced,and the mechanical properties of the structural system are analyzed from the two levels of the member and the whole structure by using the finite element analysis method.It is expected to provide some references for the popularization and application of the structure system.The main contents of this paper are as follows:(1)By combining theoretical analysis with numerical simulation,the compressive stability of double T-shaped angle aluminum axis as a structural web member is discussed in this paper.Four kinds of sections and four lengths of each section are analyzed,and 16 kinds of member model are analyzed.After reasonable simplification,the stability bearing capacity of T type aluminum and single angle aluminum is compared with that of T type aluminum and single angle aluminum respectively,and the ratio of stability bearing capacity under different aspect ratio is obtained respectively.Compared with the stability calculation formula of the current Code for structural Design of Aluminum Alloy,it is found that the formula of the Code is also applicable to the double angle aluminum.In addition,the influence of the number of joints and the distance between the joint surfaces on the bearing capacity of the joint is analyzed.(2)This paper introduces the truss aluminum alloy bilayer space grid structure system,including local structure and global geometry system.The influence of different chord strengthening schemes and geometric parameters(vector span ratio,thickness span ratio and radial mesh number)on static performance is analyzed.A reasonable and efficient strengthening scheme and the variation of static performance index with the main geometric parameters of the structure are obtained.(3)In this paper,the overall stability performance of the structure system is discussed.The buckling analysis of the lattice shell model is carried out by taking the buckling eigenvalue and the nonlinear stability coefficient as the research contents,and the stability bearing capacity of the lattice shell model is analyzed with the consideration of the material and the geometric double nonlinearity.The instability mode of the structure and the influence of initial defects and geometric parameters on the stability bearing capacity of the structure are obtained by parameterized analysis.The influence of temperature on the stability bearing capacity of the structure is studied,and it is found that it is insensitive to the temperature change.(4)The dynamic performance of the structure system is studied from two aspects: the natural vibration characteristics of the structure and the time-history response under the earthquake wave excitation.The variation of the natural vibration frequency,the mode mode and the fundamental frequency of the structure under different geometric parameters are obtained.In addition,the time history curves of stress and joint displacement are obtained.At the same time,compared with the dynamic characteristics of steel latticed shell structure,it is confirmed that the structure system has good seismic performance.