Study On New-type Large-span Greenhouse Structure Systems And Joints

Initially,greenhouse satisfies productive needs.Nowadays greenhouse will develop to Entertainment Catering Integration,which due to its transparent appearance,novel style and low cost.Large-scale commercial greenhouse should meet the requirements of ventilation and lighting and improve the safety of structure.Furthermore,the interior space should be large.Planar structure is used in the existing multi-span greenhouse,which may lead to poor spatial performance and small span.Therefore,it’s better to adopt spatial structure in the greenhouse,which will improve performance.Firstly,this paper briefly presented development history of greenhouse and types of greenhouse at home and abroad.This thesis illuminates the Venlo-type greenhouse that is the typical large scale greenhouse.A successful instance of Venlo-type greenhouse is analyzed through SAP2000 simulation.It turns out that in the span of 12 m to 14 m range,the Venlo-type greenhouse has advantages of low usage of steel,good mechanical properties and high level standard which can be suitable for industrialized production.However,this kind of greenhouse has disadvantages of narrow space,small span and poor space integrity,which need improvement to expand the scope of the applicable span.Secondly,the author creates a new type of greenhouse roof structure with space truss on the basis of the Venlo-type greenhouse.The vertical stiffness and internal force distribution features are analyzed by software analog.The appropriate truss span and other dimensions are determined.The new type of greenhouse is suitable for the span of 24 meters to 42 meters with the same steel amount of Venlo-type greenhouse,which has a larger stiffness,well-distributed internal force,and significant spatial effect.A new consolidation node was developed for the new greenhouse structure that can make the fabrication,installation and transportation of large span truss.Lastly,the mechanical performances of new roof structure under symmetrical loading and unsymmetrical loading are showed through experimental comparison of ordinary truss under symmetrical loading and joggle truss under unsymmetrical loading.At the same time,the practicability of the new consolidation node are validated.