Research On Seismic Performance And Cable Parametric Vibration Of Pretensioned Reticulated Mega-structure

The pretensioned reticulated mega-structure was proposed by arranging cable-strut,which has better static property and stability.While the research on their seismic performance is deficient and the pretensioned cable has the possibility of parametric vibration.Large vibration of the cable can damage its anchoring end and lose bearing capacity,which ultimately affects the safety and durability of the structure.Therefore,it is of great theoretical and practical significance to study the seismic performance of structure and cable parametric vibration.The following research works will be carried out in this paper.(1)The in-plane nonlinear vibration equation of cable motion under axial displacement excitation is established by Galerkin Method and the influence of various parameters on cable parametric vibration are studied by numerical integration.A method is proposed based on finite element analysis to study the parametric vibration of cables in the structure.(2)The basic dynamic characteristic of the pretensioned reticulated mega-structure is studied and obtain the natural frequency and modes shape of vibration.The parametric analysis is carried out for the sequence of the first mod e shape in different directions and the influence of parameters on the structural stiffness is investigated.A series of parametric analysis studies the structure seismic response influence of ration of rise to span,length of span,section area and support conditions by using nonlinear time-history analysis method.(3)The nonlinear incremental dynamic analysis method is used to research the seismic performance of the structure in depth,including the yield element distribution,the weak position,the failure mechanism and failure mode of the structure.Through a large number of calculation results show that the failure probability of the structure under 8 and 9 degree rare earthquake is close to 0% and 15% respectively,which indicated it has splendid seismic performance and hig h safety reserve.(4)The condition and mechanism of parametric vibration of cable in the structure under different frequency harmonic load and seismic waves are studied.The results indicate that cable parametric vibration appear when the ratio of the excitation frequency to the natural frequency of cable was 2.07: 1,the amplitude of cable increased by about 13 times.The vertical displacement at the end of the cable and the axial force of the strut are partially increased,also it find that different form parameters of structure all have the possibility of cable parametric vibration.In the paper proposed a method to control the cable parametric vibration by increasing th e cable damping ratio and it have better vibration reduction.The cable parametric vibration is necessary to be considered for ensuring the safety of structure under earthquakes.The research in this paper has certain scientific significance for d esigning and promoting this type of new spatial structure and ensuring the safety and reliability of it under earthquakes.