Research On Seismic Performance Of Kiewitt-Sunflower Single-layer Reticulated Shells And Spatial Hysteretic Performance Of Circular Steel Tube

The traditional pure topological forms of single-layer reticulated shells have a lot of disadvantages, such as numerous members and complex construction, but the KiewittSunflower single-layer reticulated shells have more reasonable behavior and economic, which applied widely in engineering. However, the seismic performance of this type of structure has not been in-depth studied yet. Based on this problem, the seismic performance of Kiewitt-Sunflower single-layer reticulated shells was studied and the spatial hysteretic performance experiment of circular steel tubes used widely in the shells was conducted in this paper. The main works and conclusions are shown as below:(1) The parametric analysis on natural vibration characteristics of Kiewitt-Sunflower single-layer reticulated shells was operated, and The effects of rise-span ratio, circle number ratio, initial imperfections and surface load on natural vibration characteristics were discussed. The results show that the shell has intensive distributed frequencies, and both rise-span ratio and surface load have a significant influence on the natural vibration characteristics of the shell, and that earthquake action in three directions should be taken into account when carrying out the structural analysis because vertical and horizontal seismic actions on the shell have the same order of magnitude.(2) The analysis of Kiewitt-Sunflower single-layer reticulated shells under frequently occurred earthquake was carried out. The seismic force coefficients were counted based on about 720 analyzing resluts of the shells according to member types by using an improved formula. Effects of circle number ratio, rise-span ratio, member size and different earthquake records on seismic force coefficients were discussed. The seismic force coefficients were suggested as a reference for designing the shells. The results also show that compared with other factors, the rise-span ratio has the most effect on the seismic force coefficients.(3) The analysis of Kiewitt-Sunflower single-layer reticulated shells under rarely occurred earthquake was carried out, and the elastoplastic response regularities and failure mechanism were discussed from both macro and micro view by integrating multiple targets characteristic response. The effects of different topological forms, rise-span ratio and initial imperfections on seismic performance of the shell were discussed too. The results show that Kiewitt-Sunflower single-layer reticulated shells have good seismic performance when suffered the earthquake, and initial imperfections should be taken into account when analyzing the shell. Furthermore, rise-span ratio has remarkable influence on failure mechanism of the shell, the failure mechanism of the shell should be changed from strength failure to dynamic instability when the rise-span ratio decreased.(4) The spatial hysteretic experiment of circular steel tube which used widely in single-layer reticulated shells was carried out with a modified loading device. The experimental phenomena of the specimens were analyzed; the effects of diameter, thickness, axial compression ratio and length on hysteretic characteristcs were discussed to lay a foundation for the establishment of sophisticated constitutive equation. It can be thought that the experimental results obtained by using the new loading device can reflect the spatial hysteretic characteristcs more accurate. The circular steel tube shows good hysteretic performance and better energy consumption behavior even if at a large displacement.