STUDY ON ULTIMATE BEARING CAPACITY OF T-SHAPED JOINTS CONNECTED WITH CLAMPS IN STEEL GREENHOUSES

The mechanical properties of T-shaped joints commonly used in steel greenhouses were studied. Firstly, the bearing mechanism of T-shaped joints connected with clamp was analyzed and the fixing device was designed and fabricated. Then, tensile and compressive tests for 6 T-joint specimens of 2 specifications were conducted, and the failure modes, load-displacement curves and ultimate bearing capacity were obtained. At the same time, the software ABAQUS was applied and the interfacial contact and slip phenomena were considered, finite element models of T-shaped joints connected with clamps were established, and the whole process of tension or compression was simulated and compared with the experimental results respectively. The results showed that under compression, the failure mode of the two types of joints were the same, and the bearing capacity of the joints was reduced due to flexural deformation of the transverse steel tube. And the 2 kinds of joints were destroyed in different modes. The bearing capacity of joints with ϕ32 steel tubes reduced with the increase of flexural deformation of the horizontal tube, while the joints with ϕ25 steel tubes reduced due to the tearing of clamps. The reinforcement of clamps could effectively improve the bearing capacity of joints with ϕ25 steel tubes under tension. A measure to increase clamp thickness for joints with ϕ25 steel tubes to 1.48 mm was suggested.