Seismic Performance Of Reticulated Shell And Optimization Of Member Based On Energy Dissipation

The spherical reticulated shell is beautiful in appearance,good in force performance and light in weight,and has achieved rapid development in recent decades.China is in the earthquake-prone areas belt,so the seismic performance of the reticulated shell structure is worthy of study,especially for the whole process of the failure mechanism of the reticulated shell structure.From the component level,the energy consumption of the component is the embodiment of the structural seismic performance.The cross-sectional area of the steel tube which is commonly used in the reticulated shell structure,has a great relationship with the energy consumption capacity of the component.Choosing a suitable cross section can enhance the energy consumption of the structure.The following research works are carried out in this paper:(1)The cross-section size of the commonly used K8 reticulated shell is selected to establish the reticulated shell structure model.Considering the initial deformation of the structure and the roof load,the modal analysis of the reticulated shell structure is carried out.Considering the amplitude,spectral characteristics and duration of the ground motion,appropriate three-direction seismic waves are choosed and used in the incremental dynamic analysis of the reticulated shell structure.The structural response and dynamic limit load of the reticulated shell under different ground motion amplitudes can be obtained.The maximum vertical displacement and the ratio of plastic rods of the structure are selected as the performance index,and the influence of rise-span ratio,types of seismic waves and amplitude modulation ratio of seismic waves on seismic performance of the reticulated shell is investigated.Meanwhile,the optimal ratio of rise to span of the reticulated shell structure under different span conditions is obtained,and the failure mode of the reticulated shell is obtained as the dynamic instability mode.The internal force distribution of the members under earthquake action is also analyzed.Finally,the accuracy of the selected optimal rise-span ratio is verified by the total input energy in seismic of the unit steel mass.(2)According to the characteristics of bidirectional compression and bending of members under earthquake action,four loading systems that can reflect the spatial seismic action of circular steel tubes are designed to investigate the relationship between energy dissipation capacity of components and geometric parameters of components.3D loading tests of 144 components are carried out by finite element simulation to study the influence of the geometric parameters of the circular steel tube and the loading system on the hysteretic behavior of the component.The geometric parameters include the length and thickness of the component.The loading system includes four displacement loading modes and two axial loading modes.The evaluation indexes of hysteresis performance are ultimate strength,secant stiffness,ductility and energy consumption.Finally,the variation law of hysteretic behavior of components with different geometric parameters and loading systems is summarized,and the most unfavorable stress condition of circular steel tube is analyzed.In conclusion,the hysteresis loop of circular steel tube is full under 3D loading,and the energy dissipation capacity of the steel tube is great.(3)In order to make rational use of the energy dissipation capacity of steel tubes,the relationship between energy dissipation coefficient and section size is summarized.Based on the two-stage design method in engineering seismic design theory,the dynamic optimization of structures with three optimal ratios of rise to span is carried out.The constraint condition of the optimization is the seismic performance target,namely the performance requirements of frequent and rare earthquakes.And considering the maximum energy dissipation coefficient of the component section and the minimum consumption of steel as the objective function,the dual objective optimization method is used to obtain the optimal section size of the reticulated shell structure under different spans,which provides design parameters for engineering design.