Strengthening Techniques for Greenhouses

Maraveas, Chrysanthos; Tsavdaridis, Konstantinos Daniel

doi:10.3390/agriengineering2010003

Cited by 12 publications

(9 citation statements)

References 13 publications

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“…As the slope of the roof increases, the Cp values on the windward roofs change from negative to positive. Therefore, more attention should be paid to prevent deformation instability under the combination of positive wind pressure with other loads (such as constant load, snow load, crop load and movable equipment load) [64,65] . A study by Xing et al [66] indicated that the angle of around 20° was a critical roof angle for slope-shaped roofs.…”

Section: Influence Of Roof Shape and Slope Angle On Wind Pressurementioning

confidence: 99%

Wind pressure acting on greenhouses: A review

Nan¹,

Wang²,

Bai³

et al. 2021

International Journal of Agricultural and Biological Engineering

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Greenhouses are widely used in agricultural and horticultural production. With the characteristics of lightweight, small stiffness and high flexibility, greenhouses are sensitive to wind loads. In the calculation of wind loads, the wind pressure coefficient (Cp) is essential. The rationality of the value directly affects the safety and economy of greenhouses. Therefore, the Cp values estimation is one of the most important issues in the design of greenhouses. In order to make full use of the existing research results, in this study, three main methods for estimating Cp values were analyzed, namely, full-scale field experiment, wind tunnel experiment and numerical simulation. Five factors influencing the Cp values were then reviewed including greenhouse design parameters, greenhouse group, overhanging eaves, ventilation and wind direction. Based on the existing researches, suggestions for future development and research work were also put forward. Owing to the flexibility and deformability of greenhouses, the fluid-solid coupling method should be used to analyze the effects of vibrations on wind pressures. The interaction of building parameters (such as the number of spans, ridge height, roof shape and slope angle) and terrain around the greenhouse should be taken into consideration comprehensively. The destructive vortices occurred on the greenhouse should be further investigated.

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Section: Influence Of Roof Shape and Slope Angle On Wind Pressurementioning

confidence: 99%

Wind pressure acting on greenhouses: A review

Nan¹,

Wang²,

Bai³

et al. 2021

International Journal of Agricultural and Biological Engineering

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“…Calculate u i ′ , u j ′ and w i ′ , w j ′ at both ends of segment l by equation (13). Calculate N l by equation ( 11), Calculate V l by equation ( 9), Calculate M l by equation ( 10), Calculate σ max by equation ( 12); Calculate V i and V j by equation ( 11), ( 13) end do (14)…”

Section: Advances In Civil Engineeringmentioning

confidence: 99%

“…By simulating the wind speed of the airflow around and through a greenhouse structure, the influence of strong lateral wind on the leakage rate and internal pressure coefficient of the greenhouse can be studied [11,12]. e mechanical properties of various greenhouse frame structures have been studied under the action of wind load, snow load, and different load combinations [13,14]. In a study, the safety wind speeds for singlespan greenhouses were calculated and compared with the actual wind speeds and snow depths over a period of 8 years in different regions to analyze the structural safety of singlespan greenhouses [15].…”

Section: Introductionmentioning

confidence: 99%

Dynamic Response Analyses of Plastic Greenhouse Structure considering Fluctuating Wind Load

Jiang

Bai

Wang

et al. 2021

Advances in Civil Engineering

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Wind load is one of the main factors of plastic greenhouse collapse. To solve the dynamic response problem of greenhouses under wind load and determine the dangerous section of a skeleton structure, the investigated lump method is presented for the dynamic response analysis of a plastic greenhouse, considering pulsating wind on the basis of Timoshenko beam theory. First, the investigated lump is designed according to the Timoshenko beam microbody concept. On the basis of Timoshenko beam theory, the governing equations of the skeleton structure of the greenhouse are derived, and the realization process of the algorithm is also provided. Second, the accuracy and effectiveness of the proposed numerical method are verified by an example in which the bending wave of a variable cross section beam with free ends propagates. Finally, the dynamic response of the steel skeletons of plastic greenhouses is analyzed under the effect of the simulation wind speed, and the spatial distribution of the maximum node displacement and the section maximum stress of the steel skeleton are obtained. Computational results show that the displacement peak is near the top of the plastic greenhouse. The most dangerous section of the top chord in the steel skeleton is near the leeward bottom, which has a maximum stress of 219.4 MPa, and the most dangerous section of the bottom chord is near the 1 m height on the leeward side of the plastic greenhouse, which has a maximum stress of 248.5 MPa. Bending stress is the main factor of the rapid increase of stress at the bottom of the skeleton. The maximum node displacement and cross-sectional stress caused by fluctuating wind loads are higher than those caused by average wind loads. The fluctuating wind load should be considered in the wind-induced response analyses of plastic greenhouses.

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“…On the contrary, to date, the number of research works related to the structural calculation of greenhouses is more limited. There are some studies based on the structural analysis of greenhouses [22,24,[33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49], whereas, to the best of the authors' knowledge, only one paper focused on the analysis of foundations in greenhouses [50].…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, the aforementioned researchers have shown their concerns about the widespread greenhouse structure construction practice based on pre-engineered solutions without involving a specific technical project [22,38,42,45,46,51,52]. Similarly, Ha et al [39] also reported that greenhouses foundations are regularly empirically calculated regardless of the specific soil mechanics.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Multi-Span Greenhouse Structures

et al. 2020

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Greenhouses had to be designed to sustain permanent maintenance and crop loads as well as the site-specific climatic conditions, with wind being the most damaging. However, both the structure and foundation are regularly empirically calculated, which could lead to structural inadequacies or cost ineffectiveness. Thus, in this paper, the structural assessment of a multi-tunnel greenhouse was carried out. Firstly, wind loads were assessed through computational fluid dynamics (CFD). Then, the buckling failure mode when either the European Standard (EN) or the CFD wind loads were contemplated was assessed by a finite element method (FEM). Conversely to the EN 13031-1, CFD wind loads generated a suction in the 0–55° region of the first tunnel and a 60% reduction of the external pressure coefficients in the third tunnel was not detected. Moreover, the first-order buckling eigenvalues were reduced (32–57%), which resulted in the need for a different calculation method (i.e., elastoplastic analysis), and global buckling modes similar to local buckling shape were detected. Finally, the foundation was studied by the FEM and a matrix method based on the Wrinkler model. The stresses and deformations arising from the proposed matrix method were conservative compared to those obtained by the FEM.

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Strengthening Techniques for Greenhouses

Cited by 12 publications

References 13 publications

Wind pressure acting on greenhouses: A review

Wind pressure acting on greenhouses: A review

Dynamic Response Analyses of Plastic Greenhouse Structure considering Fluctuating Wind Load

Numerical Simulation of Multi-Span Greenhouse Structures

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