Study On Bending Moment Of Beam-column Joints Connected By Novel Oval-headed One-sided Bolts

A novel oval-headed one-sided bolt connection at the beam-column join can effectively solve the problem of no bolt installation space between the I-shaped steel beam and the square steel tubular column,and make the construction process and construction quality control easier.In this thesis,the novel type of oval-headed one-sided bolt is used to connect the semi-rigid joints of I-shaped steel beams and square steel columns.Its bolt head and bolt holes are oval in shape,which is quite different from the traditional circular-headed bolts.Therefore,this paper investigates the bending bearing capacity of the novel oval-headed one-sided bolted I-shaped steel beam and the square steel tubular column joint by conducting tests,finite element numerical simulations,and then combining with theoretical analysis.The conclusions of the study are as follows:(1)A total of six specimens were tested.Among them,SJ-1～SJ-3 specimens are M16 novel oval-headed one-sided bolt connection,SJ-4～SJ～6 specimens are M20 novel oval-headed one-sided bolt connection,each size of one-sided bolt is 0,0.2 and 0.4 in column axial compression ratio respectively.The results showed that all the outward extending end plates yielded and that the one-sided bolts yielded and deform until the bolt head fractured after continued loading.The initial stiffness of the joint was reduced by less than 5% and the bearing capacity of the joint was reduced by less than 2.3% by increasing the axial compression ratio of the square steel column,so it can be considered that changing the axial compression ratio has no effect on the initial stiffness and bearing capacity of the joint.The beam-column joints with the novel M20 oval-headed one-sided bolts showed an increase in initial stiffness of 21.85% and an increase in ultimate load capacity of 8.68% compared to the beam-column joints with the novel M16 oval-headed one-sided bolts.The increase in bolt size can improve the initial stiffness and ultimate bearing capacity of the joint.(2)In this thesis,the stress distribution was analyzed by ABAQUS finite element simulation,and the bending moment-rotation curve of the joint was obtained.The analysis found that the stresses in the beam-column joint were mainly in the elliptical bolt head,bolt rod,extended end plate and the bolt hole on the tensile side of the square steel tube column wall,and the deformation of the finite element model was basically consistent with the test results,and the bending moment-rotation curve was also basically consistent with the test results.(3)This thesis established theoretical model for calculating the bending moment-rotation of the I-shaped steel beam-square steel tube column joint with a novel oval-headed one-sided bolt connection.Using the component method and yield line theory,the elastic bending bearing capacity,initial rotation stiffness yielding bending bearing capacity,cut line rotation stiffness and strengthening stiffness were calculated and derived.The elastic phase curves was basically consistent with the test,and the initial stiffness was within 7% error compared with the test data;the yielding phase and strengthening phase derived from the theory had the same trend as the actual test results,and finally the general law of the bending moment-rotation angle characteristics was derived.