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The ever-increasing span can be found in the single-pipe arch solar greenhouse in recent years. But the cross-section of the rods cannot be adjusted in real time. This study aims to ensure the structural Safety Issues in this case. The research object was taken as the 12m-span solar greenhouse with a flexible thermal insulation wall. A test example was selected as the solanaceous solar greenhouse in Beijing of China. An oval tube was used with a commonly-used section of 80 mm×30 mm×2.0 mm (Height×width×wall thickness). A ‘Midas-Gen finite element software’ was utilized to analyze the greenhouse hanging, and boundary conditions. Finally, the structural parameters were optimized, according to the national standard "Agricultural Greenhouse Structure Load Code" (GB/T 51183-2016) and "Agricultural Greenhouse Structure Design Standard" (GB/T 51424- 2022). The results show that the maximum stress was 1 146.7 N/mm2, when the crop load was suspended at two points and the column feet were hinged in the greenhouse. The position of the maximum stress was the hanging point on the rear wall. The crop load C was the main control load, and the average stress value was 445.4 N/mm2 at other positions. Therefore, the small number of hanging points and the large concentrated load at the hanging points were attributed to the extremely uneven distribution of the internal force of the arch frame. The structural parameters were optimized to increase the number of hanging points, in order to disperse and reduce the local concentrated load. As such, the peak value of concentrated stress was effectively reduced to improve the uniformity of the internal force distribution of the whole structure. Furthermore, the arrangement of hanging loads was also optimized to combine with the local reinforcement and adjustment of boundary conditions. The internal force of the structure was reasonably distributed to reduce the stress of the structural skeleton. Further research was recommended that: 1) The increasing hanging points of the crops can be expected to effectively reduce the peak value of internal force. Once the hanging points increased to the three-point type, the hanging load degenerated into a secondary control load, whereas, when increased to the four-point type, the crop load quit the control role. 2) The rest direction was the partial strengthening of weak parts. The rear wall was adjusted from a single tube to a lattice column, while the maximum stress was reduced by about 48%, indicating a more significant improvement. 3) The connection form of column feet was adjusted, when fixed the front and rear column feet of the solar greenhouse with the single-tube arch frame. Once the rear wall arch frame was adjusted to the lattice columns, the hinged form was used to optimize the front column foot. This finding can also provide a strong reference for the structural form and structural materials of flexible insulation wall oval tube single tube arch type solar greenhouse. [ABSTRACT FROM AUTHOR]

Structure of solid-belly skeleton is commonly used for the solar greenhouses with light loading or narrow span due to the small section stiffness. Generally, a suitable support can be set at a certain position of south roof in a solar greenhouse, aiming to provide an economically feasible technical solution to the improvement on the safety of entire skeleton system. In this study, three types of solar greenhouse with a common span in Beijing were selected as research examples, and then to calculate the section parameter of greenhouses and the loading form, according to greenhouse design code. The main purpose of this study is to determine the impact of setting position for south roof support point on the framework safety, and thereby to obtain the optimal setting region of support point. Prior to the calculation, it needed to assume that a support point was set on the south roof skeleton of a solar greenhouse, and the position of support point can be changed along the south roof skeleton at a relatively fixed distance (about 50cm). A Midas Gen software was then used to calculate the width-to-thickness ratio, deflection, and safety factor of south roof skeleton in the solar greenhouse under 49 supporting conditions, and 255 load combinations. The results of south roof skeleton for the 8, 9, 10 m span solar greenhouse were the width-to-thickness ratios of 33, 38, 43, and the maximum deflection of 15.13mm, 14.69mm, 18.5mm, under different supporting conditions and load combinations, for the section size as 70502.0, 80602.0, 90602.0, respectively. Compared with the greenhouse design codes, all obtained data demonstrated that the skeleton structure can meet the required level of safety and stability, as the support position of south roof changed in this case. Based on the above analysis of deflection deformation and safety factor on the south roof skeleton with different support positions, it was founded that the change of support positions can make a significant impact on the safety of a south roof skeleton in a greenhouse. A feature of isolated peak curve can be used to describe the variation of deflection deformation and safety factor with the position of support points. Furthermore, the curve laws were basically consistent for three kinds of span greenhouse. Specifically, the arch deflection changed slightly, when the support point shifted from the foot to about 30% span of south roof. When the support point moved from 30% span to the ridge position, the arch deflection changed greatly, showing a trend of first decreasing and then increasing. The minimum deflection occurred, when the position of support point were set at 51%, 66%, and 59% of south roof for the 8, 9, 10 m span solar greenhouse, respectively. In a safety factor, the maximum appeared, when the position of support point were set at 51%, 72% and 71% of south roof for the 8, 9, 10m span solar greenhouse, respectively. The main conclusions can be obtained as follow: (1) By setting permanent support or temporary support at appropriate position on the south roof of solar greenhouse, the deflection deformation of arch frame can be effectively reduced, and the structural safety of framework can be significantly improved; (2) In the 8, 9, 10 m span solar greenhouse, the influence of relative support distance on deflection deformation and safety factor can be basically consistent; (3) The optimal support setting region was on the 51%-72% of the south roof in a greenhouse. The findings can provide a sound theoretical guidance to develop a novel solid-belly skeleton system, and thereby to effectively prevent some damage to solar greenhouse. [ABSTRACT FROM AUTHOR]