Research On Parametric Vibration And Dynamic Stability Of Prestressed Reticulated Mega-structures

The prestressed reticulated mega-structure was rigid-flexible composite structure by arranging cable-struct.The introducing of prestressed cables effectively improves the mechanical performance and the span of the structure.The cable is prone to various vibrations under the action of wind,rain,earthqu ake and other loads with the characteristics of lightness,softness and low damping.When the excitation frequency and the fundamental frequency of the cable meet a certain relationship,the cable may undergo parametric vibration.The small vibration of the structure will excite the violent vibration of the cable,which will bring great harm to the safety and durability of the structure.As a new type of large-span space structure system,the research on its dynamic stability is far from the same level as the research on stati c performance.Therefore,the research on the parametric vibration and dynamic stability of the prestressed reticulated mega-structure is of great significance to its practical application.The main research work of this paper is as follows:（1）A bowstring-arch model was derived and the vibration differential equation is established to analyze the mechanism of the parametric vibration of the cables on cable-strut.（2）Based on the finite element method,the parametric vibration response of the cable-strut under harmonic loads is studied.The influence of excitation amplitude,prestressing force,damping ratio of the cable and supporting pattern on the parametric vibration of the cable is analyzed.（3）According to criteria for judging dynamic stability proposed in this paper,the dynamic stability of the cable-strut under harmonic loads is studied,and the effects of rise-span ratio,span,and parametric vibration on the dynamic stability of the structure are investigated.The cable-strut with different structural parameters will experience dynamic strength failure under the vertical harmonic load while the dynamic instability failure occurs on cable-strut with different rise-span ratio and the structure with a smaller span will undergo dynamic strength failure under the horizontal harmonic load.Parametric vibration doesn’t change the failure mode of the structure.However,when parametric vibration occurs,the tension of the cable will increase sharply,resulting in an increase in the internal force of members.Under the same excitation level,the degree of plastic development is greater and the displacement is greater compared to when no parameter vibrat ion occurs（4）The dynamic stability of the prestressed reticulated mega-structures is studied under the harmonic loads and strong earthquakes,and the influence of main structural parameters on the dynamic stability is analyzed.The results show that under the horizontal harmonic loads,the structure is prone to dynamic instability failure,and under the vertical harmonic loads,the dynamic strength failure is easy to occur;under the three-way EL-Centro wave and Taft wave,the failure mode of the prestressed reticulated mega-structures is dynamic strength failure.When the structure span is larger,the structure shows the characteristics of dy namic strength failure;the rise-span ratio has little effect on the dynamic stability of the structure,and structures with different rise-span ratios all show characteristics of strength failure.