Effect of insufficient screwing depth of bolt on mechanical behavior of bolt-ball joint and stability of single-layer reticulated shell

摘要

This paper is aimed at exploring the mechanical behavior of bolt-ball joint with insufficient screwing depth of bolt. Such insufficient bolt connection was quantified as the thread screwing error. Experimental work was conducted to investigate the tensile behavior of the bolt-ball joint with insufficient bolt connection. It was found that three failure modes occurred in the joint, including the tube failure, bolt rod failure and thread failure. The tensile capacity of joint with thread failure decreased in an approximate linear manner with respect to the thread screwing error. A detailed finite element model of bolt-ball joint with thread part was established and verified by the tension test and a previous bending test. The moment-rotation curves of bolt-ball joint with insufficient bolt connection were obtained via the detailed model. These curves were then used to study the stability of Kiewitt 8 single-layer reticulated shells considering bolt-ball joints with insufficient bolt connection. The results showed that the stability capacity of reticulated shells with different rise-span ratios exhibited varied decrease. An obvious decrease occurred on the reticulated shells with 1/8 rise-span ratio. The proposed finite element methods provide a basic for the further parameter analysis of single-layer reticulated shells.