Investigation On The Placement Of Viscoelastic Dampers Of Single-layer Reticulated Shell Structures And Reliability Analysis

The technology of spatial steel structure plays an important role in the strategy of scientific research of every country,which has increasingly become a symbol of comprehensive national power and the development level of construction industry.Great endeavors are devoted to pushing the technology of spatial steel structure forward.As a representative form of spatial steel structures,large-span reticulated shell structures have been extensively applied in urban construction in recent decades.Unfortunately,contrary to the flourishing development of reticulated shell structures,the investigations on structural vibration control of shells lag behind relatively.To this end,it is of necessity to carry out the seismic control investigations related to the reticulated shell structures.Generally,modern structural vibration control theory mainly contains seismic isolation,active system and passive energy dissipation.It is widely recognized that installing viscoelastic(VE)damping devices is an effective way to reduce the structural vibration to a desired degree,which is considered as a more mature technology.The thesis puts emphasis on the structural vibration control of reticulated dome structures via VE dampers.As known,the earthquake mitigation ability of VE dampers depends strongly on their locations in the structure.Therefore,the objective of this research is to make sure a good configuration of VE dampers.Herein,the thesis based the energy equivalent theory of multi-degree-of-freedom system,puts forward an innovative placement of VE dampers,in order to mitigate the seismic input energy of singlelayer reticulated shell structures.Subsequently,the following steps are performed,to exemplify and validate the control effect of the proposed placement.(1)Deterministic analysis.Selected specified seismic records,the deterministic time history analysis is processed,respectively to the shell structure controlled by VE dampers with the proposed placement,the case controlled with the existing one,and the structure without control.Herein,the maximum nodal displacement at each time step is of great concern,in order to demonstrate the effectiveness of the proposed approach.(2)Stochastic analysis of single-layer reticulated shell structures under single support excitations.Deterministic response analysis relys much heavily on the chosen earthquake records,whose results only represent the structural response under particular ground motions.In this regard,the study takes the probabilistic characteristics of seismic loads into account.Stochastic dynamic analysis and reliability assessment of reticulated shell structures subjected to random seismic excitations are performed,based on the probability density evolution method(PDEM)and equivalent extreme-value distribution,where two index are used,one refers to the maximum displacement,the other refers to the plastic ratio.In this regard,the control effect of VE dampers arranged with the proposed method can be quantatively evaluated.(3)Probabilistic analysis of shell structures under multiple support excitations.As for the large-span single-layer reticulated shell structures,spatial variability of earthquake-induced ground motions cannot be ignored.For this purpose,the probabilistic analysis of reticulated shell structures subjected to multi-support excitation is carried out,which is modelled as a 1D-3V stochastic acceleration vector process.Through the aforementioned validations,the numerical results confirm that the proposed placement of VE dampers in this thesis turns out to be quite effective for mitigating the seismic dynamic response of shell structures.Meanwhile,the proposed method can significantly enhance the earthquake-resistant performance and the dynamic stability of reticulated shell structures.And it enables the structure have much larger reliability.