Building and Environment 41 (2006) 864–871 Structural analysis of greenhouses: A case study in Turkey Berna Kendirli à Faculty of Agriculture, Farm Structures and Irrigation Department, Ankara University, Ankara 06110, Turkey Received 15 October 2004; received in revised form 4 April 2005; accepted 13 April 2005 Abstract This study was carried out to determine the structural and functional characteristics of the greenhouses in greenhouse enterprises of Turkey. Greenhouse enterprises are widely common along the Marmara, Aegean and Mediterranean cost lines. Marmara region was selected as the study area since it is the pioneering region and has large areas allocated to greenhouses, and has various greenhouse types. Information about greenhouse types, material properties, placement, and arrangement of greenhouses in the study area was gathered by a questionnaire; then greenhouses in enterprises were divided into groups based on cover material, load bearing materials and directional placement. A total of four types of greenhouse with the most economic cross-section, one from each group, were selected and load acting on structural members of greenhouses were calculated. Loads acting on beams of each greenhouse were analysed by Force Method and Moment Distribution Method. The results obtained were compared statistically to determine the best methodology for structural analysis of greenhouses. As a result, no statistical difference was found between moments and shear forces obtained from both methods. However, a difference occurred based on greenhouse types and it was determined that the values obtained for trussed block greenhouse were higher than the other ones. r 2005 Elsevier Ltd. All rights reserved. Keywords: Greenhouse; Force method; Moment distribution method; Turkey 1. Introduction Greenhouses provide a suitable environment for the intensive production of various crops. They are designed to provide control of solar radiation, temperature, humidity and carbon dioxide levels in the aerial environment. In hydroponics greenhouses, nutrient levels and root temperatures can also be controlled. Turkey is located between the latitudes with sufficient light and temperature for greenhouse production. That’s why it has advantages over Northern European countries. In 1975, there were approximately 3500 ha of glass and plastic greenhouses in Turkey and it increased to 9100 ha in 1985; and to 14,200 ha in 1995. Total greenhouse coverage reached 29,954 ha in 2003. Approximately 22% of the total greenhouses are glass- houses, and the remaining 78% are plastic houses [1,2]. Greenhouse culture in Turkey has been widely accepted by the growers in the Mediterranean, Aegean and Marmara regions. Initially, production in greenhouses has started out as family enterprises in the country. During the last decade, large agricultural enterprises with modern production techniques have been formed and they are common in Mediterranean region, and corresponding to about 20% of the greenhouses [3]. Marmara region has a greenhouse history of about 50 years and it is the pioneering region in cut-flower production. Being closer to large markets such as Istanbul has provided an advantage to the region over the other regions. With the experiences of the years, it is possible to see small family enterprises and larger commercial enterprises together with various green- house styles in the region. That is why, Marmara region was selected as the research area to represent the development of greenhouses in Turkey. Greenhouses are constructed with a principle that they have a rigid load-bearing frame, which is placed at ARTICLE IN PRESS www.elsevier.com/locate/buildenv 0360-1323/$ - see front matter r 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.buildenv.2005.04.013 à Tel.: +90 312 317 05 50/11 45; fax: +90 312 317 41 90. E-mail address: kendirli@agri.ankara.edu.tr.