Strengthening techniques for greenhouses

Greenhouses are specially designed to provide suitable conditions which favor growth and production of plants annually. This is achieved through their unique structural characteristics which enable them to carry out their specified functions. For a greenhouse to be termed as well-designed, it must satisfy key objectives such as low construction and operation cost, efficient mechanical properties, efficient ventilation systems, low heat consumption, and allowance of high light transmittance.

Most existing greenhouses may be approved as inadequate in terms of resisting the design forces according to EN 13031 and Eurocodes due to the fact that most of them are imported by European farmers from different countries such as Italy, the Netherlands, and Spain whose climatic and structural requirements are a little different from those of European Union (EU) countries. In other cases, the cultivators construct them on their own greenhouses. For all commercial greenhouses, the major problem is that the climate and terrain settings have significant differences amongst countries (which are also evident in different areas of the same country due to the rural geographical diversity); hence, it is quite unlikely that a greenhouse which was designed to be used in a different country is acceptable for use in different regions under the mentioned standards which govern the installation and application of greenhouses in different regions. Thus, local engineers have to make changes to the structural system to adapt to the particular local geographical environment.

Previous studies by Kim et al. and Vázquez et al. showed that the design of greenhouse steel structures has several deficiencies. Kim et al. discussed the different wind loads that are predicted based on different design codes worldwide, as well as the differences, uncertainties, and their effect on the safety of vaulted and pitched roof greenhouses. Vázquez et al. investigated the performance of typical cold-formed connections for a specific greenhouse and found that the design of the joints was inefficient.

A new study combines wind and snow loads according to European standard provisions, rendering the governing load combination for the ultimate limit state (ULS) design of steel structures, which may lead to collapse. The paper also focuses on strengthening techniques such as capacity and safety improvement methods due to poor initial design or the adoption of design standards from different regions.

Traditionally, many greenhouse structures experience natural disasters and various types of collapses occur, which usually do not involve loss of human life but significant loss of money and wealth. Thus, to protect them from collapse, appropriate repair and retrofitting techniques are in need, but there is scattered knowledge to date. The paper summarizes various core methods of repairing and retrofitting of such lightweight steel structures according to the code requirements. The assessment and retrofitting of two types of existing greenhouses are also presented as case studies.

Access the full study at ResearchGate.


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