Analysis of the performance of the oval tube arch of single-tube solar greenhouses

Less shading of the steel skeleton has been the dominant structure of the Chinese solar greenhouse in recent years, due to the light structure of the single-tube arch center. The disciform arch center can hold more sections of the component, indicating the stronger carrying capacity in the same amount of steel, compares with the circular tube. Furthermore, the disciform arch center is a closed structure, compare with type C steel. The components shared a much stronger resistance to deformation. The disciform tube can be in the single arch center popular material, particularly for the current greenhouse with the light assemble structure. In this study, three groups were selected in the common spans of 8, 9, and 10m for the snow load in the Beijing region. The section size of the greenhouse and the form of load action was selected, according to the "Code for the design load of horticultural greenhouse structures" and "Code for the design of Chinese solar greenhouse". The cross-sectional dimensions of the Chinese solar greenhouse with three spans were 100 mm?40 mm?5 mm, 100 mm? 40 mm?2.5 mm, 110 mm?40 mm?2.5 mm, where the flat oval pipe was used as the load-bearing arch. The spacing between the skeletons was 1.0 m, and the longitudinal support was adopted as a circular tube of φ25 mm×1.5 mm. The material of the skeleton was the ordinary carbon structural steel Q235. The design life of the Chinese solar greenhouse was considered as 10 years. Permanent loads were generated by the arches and permanent equipment, whereas, the variable loads mainly included a load of crop, snow, wind, roof live, and thermal insulation. The building was set as four types of attachment (consolidation with consolidation, hinge with hinge, consolidation with hinge, and hinge with consolidation), three types of span (8, 9, and 10 m), and two kinds of roof form (sharp roof ridge and round roof ridge), where the straining beam was set in different positions. A computational model was established to determine the influence of straining beam position on the single-tube arch center axial force, bending moment, and maximum stress ratio. The software (3D3S) was selected for the modeling operation in a wide range of applications for the rhino curve. The modeling accuracy was improved to import any section form. If the arch center was connected with the back wall, whatever the kind of attended mode, the straining beam was avoided, when the arch center connected with the base used the solid connection. When the arch center connected with the base used the hinge joint, the straining beam was set. In four connection modes, the stress ratio of the arch frame was the largest, which was hinged with the foundation and the back wall. The stress ratio of the arch frame was the smallest, which was hinged with the foundation and consolidated with the back wall. The connection between the arch and the foundation was hinged to consolidate the connection with the back wall in the engineering design. In this case, the tie rod was set more effectively. The roof straining beam presented the curve in the greenhouse with the different spans, when the arch center connected with the base use hinges, or with the backwall use hinges. The structural bearing force was required the greenhouse span of 9 m. Consequently, the roof form was a round arc without a straining beam, otherwise, the roof can be sharp with the straining beam. The findings can provide the theoretical support to design the oval-tube arch center of a single-tube Chinese solar greenhouse.