Study On Mechanical Performance Of Elliptical Suspendome Based On The Semi-rigid Joint

Elliptical suspendome is a kind of green building that has high efficiency for its great adaptability to architectural sculpture and function.It has won widely in applications domestic infrastructure construction for the past few years.However,related research on this structure is still limited,especially on influence of joint stiffness.Due to its different structural morphology,present research results on spherical suspendome can not be directly used on this structure,causing limitations on the development and application of elliptical suspendome.Based on the study of a large amount of relevant literatures at home and abroad,the different calculation formulas of joint stiffness were compared and analyzed.Then the research result of the mechanical properties of the spatial grid structure considering the influence of the stiffness were overviewed,The research status of the mechanical properties of the space grid structure considering the influence of the node stiffness is expounded.The main contents of this paper are presented.Based on the investigation of the specifications of the upper reticulated shell nodes and steel pipes in the elliptical suspendome completed in recent years,combining the actual engineering practice and the existing norms,the orthogonal design method was adopted and considering the test equipment and site,Node design of the experimental program.After that,the material test of the test specimen was completed and the stress-strain relationship of the steel was obtained,which provided the data support for the following finite element analysis.Nine kinds and six kinds of welded hollow sphere joints were selected respectively,and the joint stiffness test was carried out.The mechanical properties of the joints of the welded joints of round steel pipes with axial force and bending moment under pure bending moment were visually investigated.The results obtained under different stress state bending stiffness of the node size.It is found that the influence of diameter on the ball diameter(d / D)is the greatest,the influence of the ball wall thickness(t)is the second,and the influence of the steel pipe wall thickness(?)is the least.The eccentricity(e)has little influence on the bending stiffness of the joint.According to the test phenomenon and the analysis suggestion: when the bending moment is bigger,the ratio of the welding ball wall thickness and the steel pipe wall thickness(t / ?)should not be less than 2.0.The finite element analysis model of welded hollow sphere joints was established by considering the influence of geometric nonlinearity by using linearly enhanced stress-strain relationship and Von-Mises yield criterion.The mechanical properties of welded hollow ball joints under different load combinations were also studied.Arc-length method iteratively tracks the moment-rotation curve of the ball.According to the experimental results and finite element analysis,the calculation formula of the flexural rigidity of welded hollow ball joints is proposed.Available for actual engineering design,but also for reference to amend the relevant rules.Finally,with the support of 2022 Beijing Olympic Winter Games venues-the Northern College Gymnasium slingshot dome project,finite element analysis software Midas Gen were used to comparatively analyze the stiffness of stiffened nodes and the suspen-dome structure model of completely connected joints.Considering the semi-rigid joints,it is found through static analysis that the stiffness of the joints has a great influence on the bending moment of the middle member and the side member at the symmetry axis of the chordal dome,the maximum displacement of the upper reticulated shell increases about 30% Reticulation maximum internal force little change.By means of structural eigenvalue buckling analysis and nonlinear analysis,the critical load coefficient of the structure is reduced.When the semi-rigid joints are considered,the natural frequencies of the first ten stages of the structure are close to each other.After ten-order,the natural frequencies of the structures are lower but the overall gap is small.