Research Paper Integrated structural design methodology for agricultural protecting structures covered with nets D. Briassoulis*, A. Mistriotis Agricultural University of Athens, Department of Agricultural Engineering, Iera Odos 75, 11855 Athens, Greece article info Article history: Received 30 October 2008 Received in revised form 22 September 2009 Accepted 23 October 2009 Published online 26 November 2009 The use of agricultural nets is increasing rapidly in a similar manner to the increase in greenhouse plastic covering materials. The expansion of nets in agriculture is expected to have a strong impact on the economy by improving the cost effectiveness of low-input agriculture. A methodology is proposed to support the design of new optimised net-sup- porting structural systems, fully exploiting the advantages offered by novel agricultural nets. The first step in the design procedure concerns the determination of loads and load combinations. The determination of wind loads, other actions and load combinations are briefly presented, based on a critical analysis and synthesis of available research results on the aerodynamic and airflow characteristics of nets and the special characteristics of the net-structural systems and on appropriate adaptation of relevant standards for design actions, when available. The design criteria on loads and load combinations are combined with the design criteria governing the analysis and design of nets and the functional design requirements. All design criteria are integrated into a methodology for the structural design of net-supporting structural systems. The proposed design methodology is expected to allow for the design of low cost optimised structures. ª 2009 IAgrE. Published by Elsevier Ltd. All rights reserved. 1. Introduction Agricultural plastic nets are popular materials for construct- ing crop protecting structures against natural or biological hazards such as hail, wind, or insects and birds (Castellano et al., 2008). However existing design standards do not provide a methodology for the design of integrated agricultural nets – supporting structures and systems. The design and use of agricultural nets is more or less empirical and the design and construction of the supporting structures are grossly empir- ical or based on modified greenhouse frames or constructions made by farmers, which usually pay little respect to the environment. The present work was carried out in the framework of a European research project (AGRONETS project, 2004) to support the design of new optimised net- supporting structural systems, fully exploiting the advantages offered by these interesting novel materials. In particular, the evaluation of the mechanical behaviour and the determina- tion of the aerodynamic characteristics of the nets should be combined with the agronomic requirements for specific agri- cultural applications to develop design criteria for protecting structures covered with nets. The determination of load requirements represents the first step in the design procedure. However, the calculation of loads for permeable agricultural protecting structures has not been the subject of any national or European standard or code of practice, with a few exceptions for wind loads on permeable parapets covered partially by the relevant provisions of the * Corresponding author. E-mail address: briassou@aua.gr (D. Briassoulis). Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/issn/15375110 biosystems engineering 105 (2010) 205–220 1537-5110/$ – see front matter ª 2009 IAgrE. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.biosystemseng.2009.10.010