Energy Based Dynamic Stability Analysis Of Single-layer Reticulated Shell Structures

The large-span single-layer reticulated shell structures are widely used in practical engineering as an important types of large-span spatial structure.Meanwhile,the dynamic instability phenomenon could be observed when single layer reticulated shell structures are subjected to seismic loadings.In this regard,it is of great importance to ensure the safety of single-layer reticulated shell structures under seismic excitations,which becomes one of hot topics in the theoretical research of large-span spatial structures.In this thesis,the shortcomings of previously developed methods for seismic stability analysis of single-layer reticulated shell structures are first revisited.On this basis,the physical mechanism of seismic instability of single-layer reticulated shell structures is investigated from the perspective of energy variations of structure-excitation system.The characteristics of energy responses of single-layer reticulated shell structures under seismic loadings are studied and an energy function could be formulated accordingly to identify the seismic stability of single-layer reticulated shell structures.Then,a new energy-based criterion can be established for seismic stability analysis of single-layer reticulated shell structures.By using the proposed criterion,parametric analyses are performed to investigate the impacts of different structural parameters on the seismic performance of single-layer reticulated shell structures.Some meaningful conclusions could be arrived for seismic design of practical single-layer reticulated shell structures.The contents of this thesis are introduced as follows:(1)First,the existing criteria for seismic stability analysis of structures are rechecked,where the deficiencies of these criteria are pointed out.Then,the physical mechanism of dynamic instability of single-layer reticulated shell structures under seismic loading is studied from the point of view of energy variations of structure-excitation system.On this basis,a new energy-based criterion for seismic stability of single-layer reticulated shell structures is proposed,where the input seismic energy and intrinsic energy of the system are of great concern.(2)The characteristics of energy responses of single-layer reticulated shell structures under seismic loadings are carefully studied.Then,the concept of the intrinsic energy of structure-excitation system is put forward.It is found that when theintrinsic energy of the structure exceeds its seismic input energy,the dynamic instability could be observed.In this regard,an energy function could be formulated to quantitatively identify the seismic stability of single-layer reticulated shell structures.Moreover,an energy-based criterion is proposed accordingly for seismic stability analysis of single-layer reticulated shell structures.In addition,the characteristics of some seismic responses of single-layer reticulated shell structures before and after dynamic instability judged by the energy-based criterion can be also employed as the auxiliary indices to further validate the judgement.The vadality and superiority of the proposed criterion for seismic stability analysis of single-layer reticulated shell structures are demonstrated by comparisons with widely used B-R criterion.(3)By using the proposed criterion,a large-scale of seismic time-history responses analyses of single-layer reticulated shell structures are carried out with consideration of different structural parameters.The minimum energy functions,the maximum nodal displacement,and the different ratios of yielding element,etc.,are adopted as the characteristic responses when different types of single-layer reticulated shell structures,and different levels of peak accelerations are considered.In this regard,a comprehensive understanding of seismic performance of single-layer reticulated shell structures can be achieved with respect to different structural parameters.Finally,the meaningful conclusions are obtained.