Study On Seismic Performance Of A New Type Of Prefabricated Beam-column Joints With Cantilever Beam Splicing

As a kind of green building with energy saving and environmental protection,prefabricated steel structure building has the advantages of good seismic performance,highly industrialized,and short construction period.It has become the mainstream trend of high-rise buildings and super-high-rise buildings in recent years.Based on the investigation and summary of beam-to-column connections suitable for prefabricated steel structures at home and abroad,a new type of prefabricated beam-to-column joints with cantilever beam segment splicing is proposed in this paper.The seismic performance of the joint with cantilever segment splicing is carried out by means of the combination of experiment and finite element analysis,The main research contents and results are as follows:(1)Four full-scale specimens of prefabricated beam-column joints with cantilever beam segment splicing were designed.The failure modes of joints with different number of stiffeners,L-shaped angle steel short leg length and beam-column connection direction were analyzed.The results showed that there was no obvious shear failure in the core area of cantilever beam splice joints,and the failure modes of specimens under different design parameters were basically the same.(2)Based on the data collected from the tests,the moment-rotation hysteresis curves of the joints were drawn,and the seismic performance indexes such as stiffness degradation,ductility and energy dissipation capacity of the joints were studied in depth.The results showed that the hysteretic curve of the joints was relatively full,which indicated that the specimens had strong plastic deformation capacity.Compared with the single stiffening rib specimens of the cantilever beam section,the seismic performance of the cantilever beam section with double stiffening has not been significantly improved.Increasing the length of short leg of L-shaped angle steel has no obvious effect on the initial stiffness.Compared with the direction of strong axis connection of cantilever beam segment splicing joints,the rigidity,bearing capacity and ductility coefficient of the specimens are reduced by using the direction of weak axis connection of cantilever beam segment.(3)On the basis of experimental research,finite element analysis of cantilever beam splice joints was carried out.The failure mode,moment-rotation hysteresis loop and skeleton curve were obtained and compared with the experimental results.On the basis of validating the model,the finite element parameters of the joints are extended from five aspects:the number of stiffening ribs,the thickness of transverse plate,the thickness of ear plate,the thickness of L-shaped angle steel and the number of bolts on the flange of the beam.The results showed that the finite element analysis results were in good agreement with the experimental results.Changing the number of stiffening ribs and flange bolts in cantilever beam section has a significant impact on the seismic performance of joints,followed by the thickness of L-shaped angle steel long and short limbs,and the thickness of cantilever beam section transverse plate and ear plate has the smallest impact on the performance of j oints.(4)Based on the bending moment-rotation curves of the joints in test and finite element analysis,the initial rotation stiffness of the joints was calculated,and it was determined that the joints with cantilever beam segments belong to semi-rigid joints.On this basis,a moment-rotation curve model was established.The results showed that the proposed moment-rotation relationship model had good accuracy,which can be used as a reference for the design and practical application of new joints.