桁架拱塑料大棚骨架平面内竖向荷载受力性能试验

Experimental on Mechanical Performance of Truss Arch Plastic Greenhouse Skeleton Subjected to Vertical Load

桁架拱塑料大棚在我国北方寒区广泛使用且数量庞大。由于我国北方寒区雪荷载大,而多数大棚骨架设计制造不合规,冬季常有暴雪导致的大棚坍塌事故发生。为研究桁架塑料大棚骨架在平面内竖向荷载的受力性能,以节点间距及桁架拱高度为影响因素,研制了4榀桁架拱塑料大棚骨架及试验装置。采用竖向加载的方法得到了桁架拱塑料大棚骨架竖向荷载作用下的试验现象、骨架极限荷载及位移等试验数据。通过极限荷载数据分析得到了影响桁架拱塑料大棚骨架承载力因素排列顺序为:矢高>上弦节点间距>桁架高度。通过分析骨架荷载-位移曲线得到了骨架弹性极限荷载及对应的弹性位移,并通过分析骨架变形形态得到了骨架进入平面外屈曲的位置和屈曲状态。采用ABAQUS建立了桁架拱塑料大棚骨架三维线性有限元模型,通过跨中及l/4跨处的荷载-位移曲线试验值与模拟值对比分析,验证了有限元模型的正确性。研究成果可为桁架拱塑料大棚使用阶段受力和后续非线性屈曲稳定有限元分析提供参考。

Truss arch plastic greenhouses are widely used in north cold region of China with a large amount.Due to heavy snow loads and rough manufacture,greenhouse collapsed frequently in north cold region of China in winter which brought serious economic loss and even threaten personnel security.In consideration of this circumstance,the skeleton of greenhouse made of qualified steel was tested by vertical load.Taking rise of skeleton,distance of upper chord joint and height of truss arch as factors,the orthogonal experimental method was applied to design four truss arch plastic greenhouse skeletons with three factors and two levels.Moreover,the test device was designed.All skeleton models and test device were manufactured and the test points were installed.Test phenomena,ultimate load and displacement data of skeleton were obtained under vertical loading.The ultimate load data was analyzed and it shows that the factors affecting the ultimate carrying capacity of skeleton is:rise of skeleton ranks first,and distance of upper chord joint ranks second and height of truss arch is the least.3D linear finite element models of truss arch plastic greenhouse skeleton were established by using finite element software ABAQUS.The model was verified correct by comparison of the test and the calculated load-displacement at mid span and l/4.It shows that the elastic stage of the model can be used to analyze the properties of skeleton in service.All these work provide basis and cases for the following mechanical performance of truss arch plastic greenhouse during service state and the deep nonlinear buckling stability analysis using finite element method.