Sliding thermal blanket systems have been widely used as an energy-saving facility in solar greenhouses. However, the opening mechanism is still lacking in the structural skeleton and load conditions for better mechanical performance. It is also required to specifically optimize the structural safety, standardized design, and performance of such greenhouses, particularly under critical vertical loads, like snow accumulation. In this present study, a sliding thermal-blanket-adapted solar greenhouse was proposed with the skeleton of a 13.6 m span, typically for Shenyang City, Liaoning Province, Northeast China. A systematic investigation was conducted to integrate a 1:1 full-scale skeleton loading test with Finite Element Analysis (FEA) simulation using Midas-Gen software. The mechanical response of the greenhouse structure was validated under vertically applied loads. The experimental and numerical protocols were designed to simulate realistic loading conditions. Vertical load was also applied to the front roof surface. Load-displacement curves were obtained from three measurement points: the base connection of the rear roof, the inflection point of the rear wall column, and the mid-span section of the front roof. The global and local deformation behavior was analyzed after measurement. Furthermore, the internal force distribution over the entire skeleton was obtained to identify structural vulnerabilities and potential failure initiation zones. The bearing capacity of the structure under the defined vertical load case was determined using experimental and numerical approaches. The results showed that there was high-level consistency between the measurement and the computation. Both the experimental skeleton and the FEA model also exhibited a two-stage trend of the load-displacement curves under identical loading and boundary conditions: an initial linear elastic stage followed by a nonlinear deformation, indicating better agreement. Quantitatively, a slightly higher overall structural strength was predicted using the FEA model. Meanwhile, the ultimate bearing capacity was numerically derived as 24.19 kN, which was marginally greater than the experimental average of 23.35 kN. The relative error between them was only 3.62%. The accuracy and reliability of the FEA model were effectively validated to simulate the structural behavior of the greenhouse type. The geometric parameters of the greenhouse skeleton (span, ridge height, and purlin spacing) remained constant for the subsequent structural optimization. Two modification strategies were explored to enhance the performance: 1) The weak point was identified at the inflection point of the rear wall column; 2) The structural boundary conditions were modified to reinforce local weaknesses and then redistribute internal stresses for the global efficiency. The actionable insights were yielded after optimization. Firstly, the out-of-plane lateral bracing was enhanced at the rear column inflection point. Once the spacing of these additional lateral constraints was reduced to 1.5 m and even to 1.2 m, the ultimate load capacity of the skeleton increased substantially, with the maximum enhancement of 26.90%. The strength was accompanied by a concurrent increase in the displacement at the measurement points, highlighting a trade-off between load-bearing capacity and deformation. Secondly, the boundary conditions were altered to pose a profound impact on both the overall load-bearing capacity and the fundamental failure mode of the structure. Specifically, when the support condition at the base of the rear wall column was shifted from a typical pinned or partially restrained connection into a fully fixed (embedded) condition (denoted as GG in engineering terms), a significant redistribution of internal forces occurred. The redistribution led to a shift in the location of the relatively weak section within the skeleton. Consequently, the ultimate load capacity of the optimal structure increased by 16.99% under the boundary conditions. In conclusion, the overall mechanical performance of solar greenhouse skeletons was achieved in the sliding thermal blanket systems. Two practical measures were substantially improved: The out-of-plane lateral constraints increased at the critical inflection point of the rear columns, while the rotational and translational fixity were enhanced at the base of these rear column footings. The local weak areas were effectively strengthened to promote a more favorable redistribution of internal stresses for the structural safety margin. Ultimately, a reliable full-scale experimentation was combined with the advanced simulation and optimization for the structural safety, performance, and design of the solar greenhouses under vertical loading. The findings can greatly contribute to the structural engineering and protected horticulture facility in modern agriculture.

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 1146.7 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.

This study aims to clarify the influence of column foot joint size on the joint bearing capacity. Taking a Venlo greenhouse project in Zhuhai as the case, a systematic analysis was first implemented on the characteristic internal force of steel column foot. The center column foot joint was subjected to the axial tensile bending under wind load, due to the bending moment and shear force. The side column foot joint was mainly using axial tensile force, and subjected to axial tensile shear under wind load. Secondly, an optimal design was made on the column foot joint of the center and side column, according to "Code for Design of Concrete Structure", "Regulations for Design of Chemical Equipment Foundation", and "Manual of Concrete Structure". The edge distance of the anchor bolt for the column foot joint of the center column was 100 to 150 mm. The edge distance of the anchor bolt at the foot joint of the side column was 125 to 200 mm. Finally, the bending resistance to the foot joint of the center column, the shear resistance to the foot joint of the side column, and the failure mechanism were studied by numerical simulation and experiment. The results show that the failure of the center and side column was divided into the elastic, yield and ultimate bearing capacity stages. The yield point determined by the apogee accurately represented the moment, as the joint stiffness changed. The yield load and ultimate load of the three kinds of joint decreased with the reduction of the joint structure, the yield load of the central foundation short column joint decreased by about 10% per stage, and the ultimate load decreased by about 7% per stage. Once the edge distance of the anchor bolt in the side column joint was reduced by 25 mm, the two loads were reduced by about 20%. The failure mode of the central foundation short column joint was the concrete conical failure on the tension side. The failure mode of the side column joint was that the concrete wedge was pushed out. The diameter of the anchor bolt posed the greatest influence on the bearing capacity of the two joints under different structures, both of which were more than 15%. There was a small influence of the shear connector on the central foundation short column joint. The influence on the side column joint was less than 10%, due to the different load types. The smaller the sizes of the two joints were, the less outstanding the influence was. The thickness of the bottom plate shared the greater influence on the stiffness of the center column node and the lesser influence on the side column node. The shear connector had the lesser influence on the bearing capacity of the center column node and a greater influence on the bearing capacity of the side column node. The design requirements of embedded parts in “Code for Design of Concrete Structures” can fully meet the bearing capacity requirements of column foot bolt joints of greenhouse structures to resist horizontal forces, indicating the large bearing capacity reserve. The finite element modeling can be used to accurately simulate the mechanical properties and failure of the anchor bolt joint. The finding can also provide a strong reference to design the anchor bolt joint of multi-span columns in the greenhouse.